ACUS48 KWNS 260859
SWOD48
SPC AC 260858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Mon May 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
A mid-level trough will move eastward into the eastern U.S. on
Thursday, as a front remains over the Gulf Coast states and southern
Plains. Thunderstorm development will be possible near and to the
south of the front Thursday afternoon, with the greatest convective
coverage expected over parts of east Texas and the lower Mississippi
Valley. An isolated severe threat will be possible during the day on
Thursday as surface heating takes place. Any severe threat should be concentrated in areas where low-level convergence becomes maximized
near the front. At this time, confidence concerning a more focused
severe threat area is low.

On Friday, the front is forecast to move southward across the
southern Plains and Gulf Coast states. Moderate instability is
forecast to the south of the front across parts of south-central and
southwest Texas, and across parts of Florida. Isolated to scattered thunderstorms may develop in these areas, with a marginal severe
threat possible.

On Saturday, northerly flow at mid-levels is forecast to develop
over the Great Plains. In response, some models suggest surface high
pressure will be dominant across the Great Plains. This would limit
severe potential. However, other model solutions suggest that some
low-level moisture could return northward into the southern Plains.
If this occurs, isolated to scattered thunderstorms that develop in
the afternoon could have a marginal severe threat. Predictability is
low concerning any specific scenario.

...Sunday/Day 7 and Monday/Day 8...
Northerly flow at mid-levels is forecast to remain over the Great
Plains on Sunday, as a trough moves east-southeastward across the
Gulf of America. At the surface, a large area of high pressure is
forecast over the central and eastern U.S. Although isolated to
scattered thunderstorms could form Sunday afternoon over parts of
the Great Plains and Mississippi Valley, any severe threat is
expected to be isolated. This same setup is forecast to continue
into Monday.

Further northwest into parts of the northern High Plains on Monday,
model forecasts suggest a trough could move through the northern
Rockies and approach the northern High Plains. An axis of moderate
instability is forecast to develop by afternoon across parts of
western South Dakota and eastern Montana, where a severe threat
would be possible. However, predictability at this range is low.

..Broyles.. 05/26/2025

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ACUS48 KWNS 270859
SWOD48
SPC AC 270858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Tue May 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
On Friday, a mid-level trough is forecast to move eastward from the
mid Mississippi Valley into the eastern U.S. At the surface, a moist
airmass is forecast to be located from the Gulf Coast states
northeastward into the Carolinas, where moderate instability should
be in place by afternoon. Ahead of the trough, large-scale ascent
should support scattered thunderstorm development, with the greatest
convective coverage expected from Georgia northeastward into the
Carolinas. Model forecasts suggest that moderate deep-layer shear
will exist ahead of the trough, which will contribute to a
possibility for severe storms from mid afternoon into the early
evening. Large hail and wind damage would be the primary threats.

On Saturday and Sunday, a cold front is forecast to move southward
across the Gulf of America, as northwesterly mid-level flow develops
over the central U.S. A shortwave trough is forecast to move
southeastward from the central Plains on Saturday into the lower
Mississippi Valley on Sunday. Scattered thunderstorms should develop
ahead of a shortwave trough each afternoon and evening. An isolated
severe threat will be possible. However, the combination of
instability and deep-layer shear is not expected to be sufficient
for a greater severe threat.

...Monday/Day 7 and Tuesday/ Day 8...
A pronounced mid-level ridge is forecast to develop on Monday across
the central U.S., with the ridge moving eastward into the Great
Lakes on Tuesday. In the wake of the ridge, strong to severe
thunderstorm development will be possible over parts of the northern
Plains Monday afternoon and evening. On Tuesday, model forecasts
suggest that scattered thunderstorm development could take place
ahead of the trough in the upper Mississippi Valley, with additional
storm development over the lower to mid Missouri Valley. Although a
severe threat may develop, predictability for early next week is low
at this time.

..Broyles.. 05/27/2025

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ACUS48 KWNS 280901
SWOD48
SPC AC 280900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed May 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
...Saturday/Day 4 and Sunday/Day 5...
From Saturday into Sunday, a mid-level shortwave trough is forecast
to move from the central Plains into the Southeast. Instability is
not forecast be particularly strong head of the trough. However,
large-scale ascent will support scattered thunderstorm development
on Saturday in parts of the central Plains and Ozarks, and on Sunday
from east Texas into the lower Mississippi Valley. Deep-layer shear
should be adequate for isolated severe thunderstorm development. The
threat is expected to be marginal.

...Monday/Day 6 to Wednesday/Day 8...
During the early week period, a mid-level ridge is forecast to move
across the central U.S., as a shortwave trough moves through the
Desert Southwest. Ahead of this feature, low-level moisture will
increase across the Great Plains, as low-level flow strengthens in
the wake of the ridge. Surface dewpoints are expected to increase
into the 60s F across much of the Great Plains, which should allow
for moderate to strong destabilization in some areas during the
afternoon. Although large-scale ascent will generally be weak across
most of the Great Plains, thunderstorm development will be possible
Monday afternoon over parts of the High Plains. An isolated severe
threat could develop late Monday afternoon into the evening along
the western edge of the stronger instability from eastern New
Mexico, northward into western South Dakota.

During the mid week, the shortwave trough is forecast to move across
the central U.S. on Tuesday and into the Great Lakes on Wednesday.
Thunderstorm development is expected across an unstable airmass,
which is forecast to be located in the Great Plains. Forecast
instability and deep-layer shear suggest a severe threat will be
possible in areas that have sufficient large-scale forcing, although
confidence is low concerning any potential scenario. If model runs
maintain consistency and show more agreement among solutions over
the next couple of runs, a 15 percent area may be needed in parts of
the Great Plains during the early to mid week.

..Broyles.. 05/28/2025

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ACUS48 KWNS 290812
SWOD48
SPC AC 290811

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0311 AM CDT Thu May 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
...Sunday/Day 4 and Monday/Day 5...
On Sunday and Monday, a mid-level ridge is forecast to move eastward
across the north-central U.S. A low-level jet is forecast to develop
in the High Plains on Sunday with this feature strengthening on
Monday, as a trough moves through the Rockies. In response,
low-level moisture will increase across the Great Plains, allowing
for moderate destabilization across much of the region during the
day. Scattered thunderstorm development is expected Monday from
parts of the southern and central High Plains, northeastward along a
cold front into the Dakotas. Although deep-layer shear is not
forecast to be particular strong, the models do suggest that strong
instability will be possible across parts of the Dakotas by late
Monday afternoon. This likely would support a large hail and
wind-damage threat.

...Tuesday/Day 6 to Thursday/Day 8...
On Tuesday, the shortwave mid-level trough is forecast to move
eastward into the southern and central High Plains. Scattered
thunderstorms are expected Tuesday afternoon from the mid Missouri
Valley southward into eastern Kansas and east-central Oklahoma. In
addition to moderate/strong instability, large-scale ascent and
moderate deep-layer shear should support a severe threat during the
afternoon and evening. Supercells would be possible, with isolated
large hail and wind damage. Tornadoes could also occur.

On Wednesday, the cold front is forecast to move southeastward into
the mid Mississippi Valley, and southward into the southern Plains.
Mid-level flow near the front will be southwesterly. Ahead of the
front, surface dewpoints should be from the 60s to the mid 70s F,
which will contribute to moderate instability by afternoon. Although
deep-layer shear is not expected to be that strong near the front,
the instability should be enough for isolated severe storms in areas
where strong surface heating occurs. Predictability is low
concerning where the greater severe threat will be.

On Thursday, the front is forecast to move into the Southeast.
Thunderstorm development will be possible by afternoon along and
ahead of the front, from the Texas Coastal Plain northeastward into
the Gulf Coast states. Although moderate instability should be in
place in some areas by afternoon, deep-layer shear is forecast to be
weak enough to keep any severe threat localized.

..Broyles.. 05/29/2025

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ACUS48 KWNS 300901
SWOD48
SPC AC 300859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri May 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
As mentioned in WPC's Extended Forecast Discussion, an amplified
split-flow pattern across the CONUS renders below-average
predictability through the period. Will maintain inherited
severe-weather areas for D4-5, with mesoscale severe potential
evident in D6 and beyond but with poor synoptic predictability.

...D4/Monday...
A positive-tilt mid/upper trough should shift east as an embedded
shortwave impulse over the northern Rockies tracks near the
international border over the northern Great Plains. A northeast/southwest-oriented cold front should accelerate southward
into the central High Plains while a weak frontal wave temporarily
stalls the front over the Red River Valley of the North. There are
pronounced signals for afternoon to evening convection along the
front. Initially steep mid-level lapse rates will be supportive of
scattered severe potential. But it appears that stronger mid-level
flow may lag to the cool side of the front, which may limit a
greater threat.

...D5/Tuesday...
Complex severe potential is expected across the central states.
Low-amplitude shortwave impulses should be progressing across parts
of the northern Upper Midwest to the central High Plains on Tuesday
morning. Some guidance suggests extensive overnight convection may
be ongoing within a favorably diffluent upper-flow regime,
characterized by a coupled southern-stream left-exit and
northern-stream right-entrance regime. This renders substantial
uncertainty on where more robust boundary-layer destabilization
should occur. Warm mid-level temperatures in the southern stream
should yield modest mid-level lapse rates, which further lowers
confidence. Nevertheless, a broad and rich moist sector and adequate
deep-layer shear, along with widespread convection during the afternoon/evening, indicate scattered severe storms remain possible.

..Grams.. 05/30/2025

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ACUS48 KWNS 310856
SWOD48
SPC AC 310854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sat May 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
Somewhat greater confidence exists for a more south-southwest to north-northeast oriented swath of severe on D4/Tuesday. This appears
focused from the southern Great Plains to the Midwest from midday
into early evening. Overall pattern appears less amplified after D4,
with nebulous severe potential in the central to eastern states.

...D4/Tuesday...
A low-amplitude southern-stream shortwave impulse may phase with a northern-stream shortwave trough in the Upper Great Lakes vicinity
by late Tuesday. The accompanying surface wave over KS may similarly
track northeastward along a cold front through the Upper Midwest.
Rich low-level moisture will become more prevalent ahead of the
front and should spread into at least WI. Extensive convection may
be ongoing at 12Z within an increasingly favorable diffluent
upper-flow regime that is coupled with a broad low-level jet. Amid
relatively warm 500-mb temperatures within the southwest flow regime
attendant to the southern-stream impulse, mid-level lapse rates will
likely be weak in the warm-moist sector. Where appreciable
boundary-layer heating can occur ahead of morning convection,
scattered severe storms are possible.

...D5-8/Wednesday-Saturday...
Weak mid-level lapse rates will be pervasive, suggesting that robust
diurnal heating will largely drive daily bouts of seemingly
lower-probability severe. Guidance consensus suggests a more zonal
mid-level flow regime may evolve towards D7/Friday, which would aid
in the development/expansion of the elevated mixed layer and a
return of steep mid-level lapse rates across the High Plains.

..Grams.. 05/31/2025

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ACUS48 KWNS 010832
SWOD48
SPC AC 010830

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0330 AM CDT Sun Jun 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
Enhanced mid-level southwesterlies initially present over the
central Great Lakes early Wednesday should become confined to ON/QC
as a lower-amplitude shortwave trough dampens. Trailing to the south
of this, low-probability severe is apparent on Wednesday afternoon
in the eastern Midwest, and on Thursday afternoon over the Northeast along/ahead of a decaying cold front.

Another southern-stream shortwave impulse is progged to move east
from the Southwest mid-week. But initial surface ridging downstream
over the southern High Plains suggests the potential severe area
will be limited. Greater potential may await D6-7/Friday-Saturday,
as the ridging breaks down and zonal mid-level flow returns in the
wake of the aforementioned impulse. This will yield strengthening
and expansion of the EML east of the CO Plateau. ML guidance from
both the latest 00Z SPC/NSSL GEFS and yesterday's 00Z NCAR ECENS
highlight 15 percent probabilities on D6-7/Friday-Saturday across
the TX Panhandle into western KS/OK. Potential MCVs embedded within
this regime appear too minor at this time frame to reliably
delineate an area, but bear watching for shorter-term outlooks.

..Grams.. 06/01/2025

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ACUS48 KWNS 020841
SWOD48
SPC AC 020839

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0339 AM CDT Mon Jun 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Latest guidance has trended towards a climatologically active
extended period for severe potential. It appears that 15 percent
severe areas will likely be delineated each day within a persistent
split-flow regime. Belts of enhanced mid-level westerlies should
accompany the train of low-amplitude southern-stream shortwave
impulses. Meanwhile, above-average agreement exists with the
amplification of a large-scale trough into the north-central states
towards the end of the period. This would suppress the southern
stream southward in the southern Great Plains to Deep South.

Reliably timing individual low-amplitude impulses/MCVs can be
difficult in this setup. But it appears that the initial impulse
ejecting across the southern Rockies around 12Z Thursday should
serve to focus severe potential from the TX Panhandle into southern
KS on D4. This feature may continue eastward towards the Mid-MS
Valley/eastern Midwest on D5/Friday. But with probable weak
mid-level lapse rates downstream and lack of run-to-run continuity
across guidance, will defer on a 15 percent area highlight.

..Grams.. 06/02/2025

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ACUS48 KWNS 030852
SWOD48
SPC AC 030851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Tue Jun 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
An active severe-weather pattern for repeated MCS development is
anticipated through this weekend, with more nebulous potential early
next week.

Medium-range guidance has converged to above-average consistency
with the large-scale pattern through this weekend. Enhanced zonal
mid-level flow within the southern stream should overlie a
seasonably rich and unstable air mass across the southern Great
Plains to the Deep South. Initial signal for south-central High
Plains nocturnal MCS development spreading east-southeast onto the
lower plains is evident late D3 and this will probably repeat on
D4/Friday night and perhaps on D5/Saturday night. This should
subside as a northern-stream upper trough amplifies into the
north-central states.

Remnant MCVs should focus downstream diurnal thunderstorm
development each afternoon through at least D6/Sunday. Given the
buoyancy/shear parameter space, sufficient confidence exists for
highlighting a scattered severe-storm threat on D4-5. Damaging winds
appear to be the dominant hazard in this pattern. An additional area
on D6 is plausible in later outlooks somewhere in the Deep South and
Gulf Coast States. For D7-8, severe potential is nebulous, but may
be tied to the evolution of the north-central states trough.

..Grams.. 06/03/2025

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ACUS48 KWNS 030919
SWOD48
SPC AC 030918

Day 4-8 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0418 AM CDT Tue Jun 03 2025

Valid 061200Z - 111200Z

CORRECTED FOR MISSING LABEL ON DAY 6

...DISCUSSION...
An active severe-weather pattern for repeated MCS development is
anticipated through this weekend, with more nebulous potential early
next week.

Medium-range guidance has converged to above-average consistency
with the large-scale pattern through this weekend. Enhanced zonal
mid-level flow within the southern stream should overlie a
seasonably rich and unstable air mass across the southern Great
Plains to the Deep South. Initial signal for south-central High
Plains nocturnal MCS development spreading east-southeast onto the
lower plains is evident late D3 and this will probably repeat on
D4/Friday night and perhaps on D5/Saturday night. This should
subside as a northern-stream upper trough amplifies into the
north-central states.

Remnant MCVs should focus downstream diurnal thunderstorm
development each afternoon through at least D6/Sunday. Given the
buoyancy/shear parameter space, sufficient confidence exists for
highlighting a scattered severe-storm threat on D4-5. Damaging winds
appear to be the dominant hazard in this pattern. An additional area
on D6 is plausible in later outlooks somewhere in the Deep South and
Gulf Coast States. For D7-8, severe potential is nebulous, but may
be tied to the evolution of the north-central states trough.

..Grams.. 06/03/2025

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ACUS48 KWNS 040853
SWOD48
SPC AC 040851

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Wed Jun 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
Another active day characterized by an ongoing MCS and remnant
downstream MCVs is anticipated on D4/Saturday, with a broad belt of
mainly damaging wind potential evident. Seasonably strong mid-level
westerlies are expected to remain coincident with rich low-level
moisture. Ample buoyancy should diurnally develop south of
pre-existing outflows. This multi-day pattern finally breaks down
into D5/Sunday with amplification of a large-scale trough from the
southern Prairie Provinces into the Upper Midwest. Mesoscale-focused
severe potential may linger into at least D5/Sunday over the
southern High Plains to the TX/OK Red River Valley and from the
central Gulf to south Atlantic Coasts.

Otherwise, low-probability severe potential could begin in a portion
of the northern Great Plains on D4/Saturday, in association with the
amplifying trough. This should subsequently shift eastward and
likely broaden across the Great Lakes into the Northeast through
early next week. Overall instability appears modest until a
potential increase later when stronger flow fields overlap richer
low-level moisture. Daily severe probabilities appear to be sub-15
percent at this range, with a relative maximum in the
D6-7/Monday-Tuesday timeframe over the Northeast. Current timing of
this trough exiting New England by around D8/Wednesday suggests a
relative minimum across the CONUS then.

..Grams.. 06/04/2025

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ACUS48 KWNS 050858
SWOD48
SPC AC 050856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Thu Jun 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
The active severe-weather pattern from the southern High Plains to
the Southeast should persist into D4/Sunday. A low-amplitude
mid-level trough is progged across the Southeast with a belt of
enhanced westerlies. The degree of ongoing convection on Sunday
morning lowers confidence on how broad a region of scattered
severe-storm potential exists in the Southeast. The best area for less-impactful morning convection appears to be across the South
Atlantic Coastal Plain and adjacent eastern Piedmont. Scattered
damaging winds should be the main hazard from afternoon storms in
this region.

With a brief respite in the wake of multiple MCSs on D1 to early D3,
buoyancy should become large to locally extreme across a portion of
the southern High Plains to OK/TX Red River Valley by Sunday
afternoon. Latest guidance is quite insistent on more widespread
convective development during the late afternoon into Sunday night,
along the persistent quasi-stationary front. Although
mid/upper-level winds may be weaker relative to prior days, an
increased west-northwesterly component along with the very unstable
airmass will support severe hail/wind, which could be significant.

Guidance has shown less predictability in the D5-6/Monday-Tuesday
time frame. This seems related to handling of downstream MCV
evolution from the probable Sunday night MCS over OK/TX, as well as
individual shortwave impulses embedded within the broad upper trough
over the Upper Midwest to Great Lakes. Expansive swaths of
low-probability severe are evident across the southern to eastern
states but predictability is too low for any 15 percent highlights.
By mid-week, guidance is still signaling a reduction in overall
severe potential with a synoptic pattern change to predominantly
weak shear coincident with areas of moderate to large buoyancy.

..Grams.. 06/05/2025

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ACUS48 KWNS 060853
SWOD48
SPC AC 060852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Fri Jun 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
A large MCS may be ongoing across the Ark-La-Tex vicinity on
D4/Monday morning. This MCS and attendant flow enhancement with its
MCV may support scattered damaging wind potential into the afternoon
downstream across the Deep South. How extensive an organized wind
threat persists is quite nebulous, given background mid-level
westerlies being weaker across the Southeast compared to prior days.

Sub-15 percent severe potential remains apparent across the Upper OH
Valley to Lower Great Lakes on D4/Monday, shifting east into the Northeast/Mid-Atlantic States on D5/Tuesday. A belt of strong
mid-level southwesterlies ahead of broad Great Lakes trough should
overlap parts of a weak cold front arcing south from a primary
surface cyclone over northeast ON to James Bay. Substantial
instability ahead of the front appears uncertain with progged weak
mid-level lapse rates and muted boundary-layer heating where the
stronger flow resides.

During D6-8/Wednesday-Friday, guidance continues to signal a
reduction in severe potential, as predominantly weak deep-layer
shear overlaps areas of moderate to large buoyancy.

..Grams.. 06/06/2025

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ACUS48 KWNS 070842
SWOD48
SPC AC 070841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sat Jun 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
Sub-15 percent severe potential remains apparent over the Mid-Atlantic/Northeast States on D4/Tuesday before a cold front
moves offshore. Instability progs remain weak where at least
moderate deep-layer shear is anticipated. It seems plausible that
the northern extent of larger buoyancy will be suppressed south in
the wake of extensive convection through D3 across the Southeast.

On D5-6/Wednesday-Thursday, guidance has trended towards some
amplification of a minor southern-stream shortwave impulse as it
drifts across the southern Great Plains. This could foster mesoscale
corridors of modest shear overlapping plentiful buoyancy in the
south-central states.

Western Gulf moisture will spread north and encompass much of the
central states through next weekend. Various shortwave impulses over
the Northwest may support multiple bouts of mesoscale-driven severe
potential along the northern periphery of the expansive Great Plains
buoyancy plume.

..Grams.. 06/07/2025

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ACUS48 KWNS 080849
SWOD48
SPC AC 080847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Sun Jun 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
Guidance trends remain supportive of a more active pattern across
the northern High Plains to the Upper Midwest. GEFS-based ML
guidance from SPC and NSSL are now highlighting multiple days with
mesoscale areas of 15 percent probabilities, mainly over the
northern High Plains. Western Gulf moisture will spread north and
encompass much of the central states through next weekend. Various
shortwave impulses ejecting into the Northwest may support multiple
bouts of mesoscale-driven severe potential downstream along the
northern periphery of the expansive Great Plains buoyancy plume. The
initial impulse that is expected to reach northern CA by 12Z
Wednesday has poor predictability with its downstream evolution into
the North-Central States.

Low-probability severe potential may persist for several days with a
minor southern-stream shortwave impulse drifting east from the
southern Great Plains. This could foster daily mesoscale corridors
with a severe threat, as modest shear overlaps plentiful buoyancy
initially over the South-Central States.

..Grams.. 06/08/2025

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ACUS48 KWNS 090849
SWOD48
SPC AC 090847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Mon Jun 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
Guidance remains supportive of a more active pattern across the
northern High Plains to the Upper Midwest. GEFS-based ML guidance
from SPC and NSSL depict mesoscale areas of 15 percent
probabilities, centered on eastern MT to the Dakotas. While
predictability for a specific day remains too low, the signal exists
for increasing potential during the weekend to early next week.

The initial low-amplitude shortwave trough over WY/eastern MT at 12Z
Thursday is progged to dampen as it moves east into the Upper
Midwest. An area-of-interest is evident over western SD and the NE
Panhandle on D4/Thursday afternoon, but a favorable buoyancy/shear
combination is too spatially confined for a 15 percent highlight.

A broad swath of moderate to strong mid-level southwesterlies may
persist for multiple days across the Northwest, downstream of a
large-scale trough near the West Coast. At the same time, the
expansive buoyancy plume over the central states should increase
northwestward, building higher CAPE into the northern High Plains
this weekend. Still, poor predictability persists with the
spatiotemporal details of individual shortwave impulses that may
support daily severe threats on D6-8/Saturday-Monday.

..Grams.. 06/09/2025

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ACUS48 KWNS 100849
SWOD48
SPC AC 100848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Tue Jun 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Models are in good agreement with the overall pattern through about
Sunday/D6, depicting upper ridging over the northern Plains and
rising heights across the Northeast and general troughiness over the
Northwest. During that same period, the disturbance over the
southern Plains is forecast to lift toward the mid MS Valley with
weakening trend.

The greatest risk of severe storms will generally stretch from the
northern Rockies into the northern Plains, as weak but backed
low-level winds maintain a moist plume out of the central Plains and
into MT and the Dakotas.

On Friday/D4, scattered strong storms may occur over central MT,
beneath modest southwest winds aloft and with around 1000 J/kg
MUCAPE. Instability will build further in the Saturday/D5 to
Sunday/D6 time frame, with greater storm coverage expected. However,
winds aloft will be marginal. Still, developing west to northwest
flow aloft could eventually result in an MCS pattern with attendant
wind potential. Predictability is low at this time, but the northern
and central Plains region will be monitored over the next several
days for potential categorical risk outlines.

..Jewell.. 06/10/2025

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ACUS48 KWNS 110839
SWOD48
SPC AC 110838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Wed Jun 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
For Saturday/D4 into Sunday/D5, moderate southwest flow aloft will
remain over the Pacific Northwest and toward the northern Rockies,
with a gradual flattening of the upper ridge over the northern
Plains. Then through Wednesday/D8, modest west/northwest flow aloft
is likely to persist over the High Plains. Models diverge greatly
after this time frame. However, this pattern will generally favor
daily thunderstorms along the length of the High Plains, from MT
into eastern NM during the afternoon, and persisting into parts of
the Great Plains during the evenings.

The primary driver of severe potential will be a large area of
moderate to strong instability with 2000-3000+ J/kg MUCAPE
developing daily. As storms move off the higher terrain, corridors
of wind damage may materialize. Predictability is low this far out,
but categorical risk upgrades appear likely as these periods get
closer in time. The primary risk appears to be damaging winds, but
sporadic large hail is possible with the late afternoon activity.

..Jewell.. 06/11/2025

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ACUS48 KWNS 120835
SWOD48
SPC AC 120833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Thu Jun 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
During the Sunday/D4 to Monday/D5 period, an upper ridge is forecast
to remain over the Plains, with modest southwest flow aloft over the
West. Models suggest that around Tuesday/D6, the upper ridge will
break down over the central/northern Plains, although the amplitude
and track of the wave is in question. Ample low-level moisture will
be in place from the Plains to the East Coast, with mid to upper 60s
F as far north as southern parts of the Great Lakes.

As a result of this large area of moisture and instability, widely
scattered thunderstorms will be common each day. The northern Plains
appears to have the greatest change of organized severe storms
includes MCS/s, but predictability is clearly low at this time with
the uncertain wave. However, it appears that the Tuesday/D6 to
Wednesday/D7 time frame may yield a corridor of organized damaging
wind potential over parts of the northern and central plains to
Midwest, and these trends will continue to be monitored.

..Jewell.. 06/12/2025

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ACUS48 KWNS 130901
SWOD48
SPC AC 130859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Jun 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
A mid-level ridge across the Great Plains is forecast to become less
amplified on Monday, as multiple shortwave troughs move through
westerly flow across the north-central states. A moist airmass is
forecast across much of the central and northern Plains, where
moderate to strong instability appears likely to develop by
afternoon. Along the northern edge of the stronger instability,
scattered convective initiation is expected. The instability,
combined with moderate deep-layer shear, should support a severe
threat. Large hail and severe wind gusts will be possible during the
afternoon and evening.

The mid-level ridge is forecast to move eastward into the Missouri
Valley on Tuesday, as a trough moves into the Rockies. At the
surface, a moist airmass is forecast from the central Plains into
the Missouri Valley, where moderate to strong instability appears
likely to develop by afternoon. Large-scale ascent ahead of the
approaching trough is forecast to move into the central Plains
Tuesday evening. As a result, a large area of thunderstorms is
forecast to develop from northern Kansas into much of Nebraska.
Model forecasts suggest that moderate deep-layer shear will be in
place, which would support a large hail and wind-damage threat.

The mid-level trough is forecast to move across the Great Plains on
Wednesday. A moist airmass is forecast to remain in place to the
east of the trough across the lower Missouri and Mississippi
Valleys. Ahead of the trough, moderate instability is forecast by
afternoon. Thunderstorm development is expected with this unstable
airmass from eastern Kansas northeastward into the mid to upper
Mississippi Valley. A severe threat will be possible. The greatest
potential for severe storms could be from northern Missouri into
southern Wisconsin, along and near the axis of a low-level jet.

...Thursday/Day 7 and Friday/Day 8...
From Thursday into Friday, the mid-level trough, and an associated
cold front, is forecast to move from the mid Mississippi Valley to
the Eastern Seaboard. A moist and unstable airmass should be in
place ahead of the trough. Thunderstorm development will be possible
along parts of the front, and across the warm sector. Although a
severe threat may develop as instability increases during the day,
the timing of the front remains questionable and predictability is
low.

..Broyles.. 06/13/2025

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ACUS48 KWNS 140900
SWOD48
SPC AC 140859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat Jun 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
A mid-level trough is forecast to move into the High Plains on
Tuesday, as a cold front moves southward into the central Plains.
Ahead of the front, a moist and unstable airmass is forecast by
afternoon from Kansas and southeastern Nebraska into northern
Missouri. As surface temperatures warm during the day, thunderstorm
development will likely take place along parts of the front.
Moderate deep-layer shear is forecast across much of the region,
suggesting that storms should become organized. Supercells and short
intense line segments will be possible, with large hail and wind
damage as the primary threats.

The mid-level trough is forecast to move eastward through the
central states on Wednesday, as a cold front advances southeastward
into the lower Missouri Valley and western Great Lakes. Ahead of the
front, an axis of moderate instability is forecast to be in place by
afternoon. Thunderstorm development will be likely along parts of
the front. Moderate deep-layer shear is forecast along and near much
of the instability axis, suggesting that a severe threat will again
be possible during the afternoon and evening.

...Thursday/Day 6 to Saturday/Day 8...
The mid-level trough is forecast to move eastward into the Northeast
on Thursday. Ahead of the trough and its associated cold front,
moderate instability is expected to develop by afternoon.
Thunderstorm development will be most likely from parts of southern
New England southwestward into the Mid-Atlantic. Deep-layer shear
should be sufficient for an isolated severe threat. However, there
is considerable uncertainty due to the issues of frontal timing and
instability magnitude.

From Friday into Saturday, a mid-level ridge is forecast to move
eastward from the northern Plains into the Great Lakes. Although a
moist and unstable airmass will likely be in place across the
north-central U.S., large scale ascent should be weak across most of
the region. For this reason, predictability is low concerning any
potential severe threat.

..Broyles.. 06/14/2025

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ACUS48 KWNS 150900
SWOD48
SPC AC 150859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Jun 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
A mid-level trough is forecast to move through the Upper Midwest on
Wednesday, as a cold front advances southeastward into the lower
Missouri and mid-Mississippi Valleys. Ahead of the front, moderate
instability is forecast to develop by afternoon. Thunderstorms
appear likely to form along parts of the front, with several
clusters or line segments moving eastward toward the instability
axis during the late afternoon and early evening. Moderate
deep-layer shear should support severe storms with large hail and
wind damage as the primary threats.

The mid-level trough is forecast to move into the lower Great Lakes
and upper Ohio Valley on Thursday, as the cold front advances into
the central Appalachians. As the airmass ahead of the front
destabilizes, scattered thunderstorms are expected to form along and
ahead of the front. The models suggest that moderate deep-layer
shear will be in place across much of the northeastern U.S., which
will likely support organized storms. Damaging winds gusts will be
the most likely severe threat.

...Friday/Day 6 to Sunday/Day 8...
A shortwave mid-level ridge is forecast to move into the upper
Mississippi Valley on Friday. The ridge is forecast to remain over
the region on Saturday as mid-level heights rise. Beneath the ridge,
a moist and unstable airmass will likely be in place from the lower
to mid Missouri Valley northeastward into the western Great Lakes.
Within this airmass, isolated thunderstorm development should take
place both Friday and Saturday afternoon. Instability and deep-layer
shear appear sufficient for a localized severe threat. However, the
presence of the ridge introduces uncertainty as to where the
greatest potential for convection will be. For this reason,
predictability is low.

On Sunday, a mid-level trough is forecast to develop over the
Rockies as a ridge moves into the Great Lakes region. Although a
moist and unstable airmass should be located over parts of the
northern and eastern U.S., large-scale ascent and mid-level flow is
forecast to be relatively weak in most areas. For this reason, any
severe potential is expected to remain isolated.

..Broyles.. 06/15/2025

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ACUS48 KWNS 220834
SWOD48
SPC AC 220832

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0332 AM CDT Sun Jun 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
...D4/Wednesday...
Extended-range guidance generally indicates that the persistent
upper ridge across the eastern CONUS will begin to dampen on
Wednesday. Multiple low-amplitude midlevel shortwave troughs will
move along the periphery of the upper ridge from the
central/northern High Plains into the Great Lakes. Mid/upper-level
flow will generally be rather weak, but may be locally stronger in
the vicinity of any shortwave troughs.

Some severe threat could develop where pockets of somewhat stronger
flow overlap moderate to strong buoyancy along the periphery of the
ridge. An MCS may develop late on D3/Tuesday and move across parts
of the central Plains and Midwest into at least early Wednesday.
This MCS could persist through the day, with additional development
possible along an outflow-influenced front. Other strong to severe
storms may again develop across parts of the central/northern High
Plains. Confidence regarding the details of any organized severe
threat is too low to delineate a 15% area at this time.

...D5/Thursday - D8/Sunday...
Guidance generally suggests that the persistent upper ridge will
continue to weaken with time, resulting in a more zonal pattern by
the upcoming weekend. Stronger flow may become increasingly confined
to the northern tier of states. This could lead to periodic severe
threats across parts of the northern Plains into the Great Lakes and
Northeast.

One area of interest is across parts of the northern Plains Friday
into Saturday. Some guidance takes a mid/upper-level shortwave
trough from the Pacific Northwest into the northern Great Plains
during this period, where it may impinge upon increasing low-level
moisture and instability, resulting in potential for organized
severe storms.

..Dean.. 06/22/2025

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ACUS48 KWNS 160857
SWOD48
SPC AC 160855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Mon Jun 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
...Thursday/Day 4 and Friday/Day 5...
A mid-level trough is forecast to move into the Northeast on
Thursday, as a cold front advances eastward into the central
Appalachians. Ahead of the front, a moist airmass will be in place.
Moderate instability is expected to develop ahead of the front
across the Carolinas and Mid-Atlantic. As surface temperatures warm
during the day, scattered convective initiation will likely take
place along and ahead of the front. Moderate deep-layer shear and
steep low-level lapse rates should support a severe threat during
the afternoon, with the primary threat being damaging wind gusts.

On Friday, a mid-level ridge is forecast to move eastward across the
northern Plains. Beneath the ridge, a moist airmass will likely be
in place, and moderate instability is expected to develop within
this airmass. Ahead of the ridge, thunderstorm development will be
possible in the upper Mississippi Valley during the afternoon.
Although a severe threat may develop in areas that become moderately
unstable, there is some uncertainty concerning convective coverage
due to the presence of the ridge.

...Saturday/Day 6 to Monday/Day 8...
Mid-level heights are forecast to rise on Saturday and Sunday across
the eastern half of the nation, as a large area of high pressure
dominates. In the western U.S. over the weekend, a mid-level trough
is forecast to move northeastward from the Intermountain West into
the northern High Plains. Ahead of the trough, strong to severe
thunderstorms will be possible Saturday afternoon and evening across
parts of eastern Montana. In spite of the potential, there is still
spatial uncertainty concerning the timing of the trough. The severe
threat is expected to shift northeastward into Canada on Sunday.

On Monday, southwest mid-level flow is forecast over much of the
north-central U.S. Isolated to scattered thunderstorms will be
possible over parts of the northern Plains and upper Mississippi
Valley. An isolated severe threat will again be possible, but there
is considerable uncertainty on any potential scenario.

..Broyles.. 06/16/2025

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ACUS48 KWNS 230901
SWOD48
SPC AC 230859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Jun 23 2025

Valid 261200Z - 011200Z

...DISCUSSION...
...D4/Thursday: Parts of the Midwest/Great Lakes...
An area of interest for severe-storm potential on Thursday resides
from eastern IA/southeast MN into northern IL/southern WI. A
mid/upper-level shortwave trough is generally forecast to move
across parts of the Midwest into the Great Lakes during the
afternoon, potentially accompanied by a frontal wave. While
deep-layer flow will generally remain rather modest, rich low-level
moisture and strong heating will support moderate to strong buoyancy along/south of the front. Strong to potentially severe storms may
develop as the approaching shortwave trough impinges upon the
favorable buoyancy. Uncertainty regarding frontal position and the
sufficiency of deep-layer shear precludes higher confidence at this
time.

...D5/Friday: Northern Plains...
An area of interest for Friday resides across parts of the northern
Great Plains. A mid/upper-level shortwave trough is forecast to move
across the northern Rockies toward the northern High Plains, though considerable spread remains regarding the timing of this relatively low-amplitude shortwave and attendant cold front. The front may
impinge upon strong instability across parts of the Dakotas, with
scattered storm and eventual MCS development possible. Deep-layer
shear may remain relatively modest, but the magnitude of instability
will likely support some organized severe threat.

...D6/Saturday: Northern Plains/Upper Midwest...
Some continuation of severe-storm potential is possible into
Saturday, potentially shifting eastward into the Upper Midwest.
Spread in guidance becomes quite large at this range regarding
placement of the warm sector Saturday afternoon, but strong
instability and at least modest deep-layer shear could support
severe storms along/east of the cold front.

..Dean.. 06/23/2025

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ACUS48 KWNS 170903
SWOD48
SPC AC 170901

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0401 AM CDT Tue Jun 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...D4/Friday...
A surface cyclone is forecast to deepen over the northern/central
High Plains on Friday, as a mid/upper-level trough shifts gradually
eastward across the western CONUS. Strong to extreme buoyancy will
develop by afternoon across parts of the central/northern Plains,
along/south of an effective warm front that will extend east of the
surface low. Much of the warm sector will likely remain capped, but
isolated storm development will be possible by late afternoon
near/north of the warm front, with increasing storm coverage during
the evening in response to a strengthening low-level jet. Supercells
will be possible initially, though the pattern suggests potential
for an MCS to develop and move eastward Friday night across the
upper Great Lakes vicinity.

Guidance continues to vary substantially regarding the most favored
corridor for an organized severe threat. For example, the GFS/GEFS
is farther north across ND/northern MN, while the ECMWF/ECENS is
farther south across central MN/northern WI. Severe probabilities
will eventually be needed for this scenario, but confidence is the
favored corridor is too low for a 15% area.

Strong to severe storms may also develop across the northern Rockies
and spread eastward across MT, in association with the approaching mid/upper-level trough. Probabilities will likely be needed for this
scenario in future outlooks, though confidence is too low for a 15%
area at this time.

...D5/Saturday...
A similar surface pattern is expected over the Great Plains and
upper Midwest on Saturday compared to D4/Friday. However, an
amplifying upper ridge may tend to suppress storm development
through much of the period. Some severe potential may again evolve
across MT along the northwest periphery of the ridge. There may also
be some potential for strong to severe storms along the northeast
periphery of the ridge into parts of the lower Great Lakes and New
England.

...D6/Sunday - D8/Tuesday...
An upper-level ridge will remain prominent through the weekend into
early next week across parts of the central/eastern CONUS. Strong to
severe storms and possible MCS development could continue to occur
along the periphery of the ridge, but predictability becomes quite
low at this range regarding the details of any organized threat.

..Dean.. 06/17/2025

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ACUS48 KWNS 180843
SWOD48
SPC AC 180842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Jun 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
...D4/Saturday...
An amplified upper-level pattern will continue into Saturday, with a
prominent ridge extending from the Southeast into the Midwest and
Ohio Valley, and a deep trough over much of the West. Large to
extreme buoyancy will again develop across parts of the
central/northern Plains and Upper Midwest, but the influence of the
ridge will tend to suppress storm development across the warm
sector.

While differing in the details, some extended-range guidance
suggests that an MCS (or at least its remnant MCV) that develops
late on D3/Friday will move across the far northern Great Lakes and
adjacent parts of Ontario on Saturday, and potentially into parts of
the lower Great Lakes by Saturday evening. Should such an evolution
occur, some severe threat could accompany this system, but
predictability for such a scenario at this range is inherently low.

Farther west, there is substantial spread in guidance regarding the
magnitude of low-level moisture and instability across parts of MT
and northern WY into western ND on Saturday. However, if stronger
flow associated with the western trough can impinge upon favorable
instability, then an organized severe threat could evolve during the
afternoon and evening.

...D5/Sunday...
The western trough is generally forecast to take on more of a
positive tilt and eventually deamplify on Sunday, as a substantial
shortwave and midlevel jet maximum eject across parts of the
northern High Plains. As this occurs, a cold front will move across
parts of the northern/central Plains. At this time, it appears the
organized severe threat may be limited by very warm temperatures
aloft and a tendency for stronger deep-layer flow to lag behind the
front.

Strong buoyancy may spread into parts of the Ohio Valley and
Northeast on Sunday. Some organized severe potential could develop
within the instability gradient along the periphery of the ridge,
though mesoscale details remain highly uncertain at this time.

...D6/Monday - D8/Wednesday...
Uncertainty increases into early next week regarding evolution of
the synoptic pattern, though guidance generally suggests that an
upper ridge will remain prominent across parts of the eastern CONUS,
while a weak upper trough will persist across parts of the West into
the northern and central Plains. While some severe potential could
evolve across parts of the Great Plains, Great Lakes, and Northeast
along the periphery of the ridge, details regarding favored days and
locations remain highly uncertain.

..Dean.. 06/18/2025

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ACUS48 KWNS 190847
SWOD48
SPC AC 190845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Thu Jun 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
...D4/Sunday...
The upper-level trough over the West is forecast to take on more of
a positive tilt on Sunday, as an embedded shortwave and attendant
midlevel jet maximum move across the northern Rockies/High Plains.
As this occurs, a surface low is forecast to move from SD toward the
upper Great Lakes, as a trailing cold front moves through the
northern/central Plains. Guidance varies regarding frontal timing,
though generally agrees that stronger mid/upper-level flow will tend
to lag behind the front.

While details remain uncertain, strong to potentially severe storms
may develop near/north of the surface low across parts of the
Dakotas/MN, and also along the trailing cold front into the central
Plains.

...D5/Monday - D8/Thursday...
The upper ridge across the Southeast is expected to remain in place
through at least early next week, with some guidance suggesting
potential for deamplification by the middle of the week. Multiple
shortwaves may emerge from the persistent (though weakening) western
trough through at least Wednesday, resulting in some potential for
strong to severe storms along the periphery of the upper ridge from
the Plains into the upper Midwest and Great Lakes, and possibly
parts of the Northeast. However, predictability remains quite low
regarding the details of any organized severe threats during this
time frame.

..Dean.. 06/19/2025

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ACUS48 KWNS 200844
SWOD48
SPC AC 200842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Fri Jun 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
...D4/Monday...
A mid/upper-level shortwave trough initially over the northern
Plains and upper Midwest is forecast to move into Ontario on Monday,
along the northern periphery of an amplified upper ridge over the
eastern CONUS. A cold front will move through parts of the Great
Lakes, Upper Midwest and central Plains. The strongest deep-layer
flow may tend to lag behind the front, but moderate to strong
instability could support strong to potentially severe storms along
the front during the afternoon and evening.

Farther east, strong instability is generally forecast to develop
across parts of the Mid Atlantic into New England. However, due to
the influence of the upper ridge, there is currently little signal
for diurnal storm development across this region on Monday.

...D5/Tuesday...
Extended-range guidance is in reasonably good agreement that a cold
front will move southward across the lower Great Lakes into New
England on Tuesday. Favorable low-level moisture and strong
instability could support severe-storm potential along the front
during the afternoon and evening. However, coverage of storms is
currently uncertain, due to the lingering influence of the upper
ridge, and a tendency for stronger large-scale ascent to be
displaced well north of the front.

The western upper trough is forecast to deamplify on Tuesday, with
most guidance suggesting that mid/upper-level flow will tend to
weaken downstream across the Great Plains and upper Midwest.
However, strong to locally severe storms could again be possible
near the front, which may begin to move northward across the central
Plains as a warm front through the day.

...D6/Wednesday - D8/Friday...
Predictability begins to wane by the middle of next week regarding
the evolution of synoptic features across the CONUS, though the same
general pattern of a weak upper trough in the West and an upper
ridge over the East may continue through at least Wednesday. In the
absence of any apparent strong forcing mechanisms, organized severe
potential (if any) may tend be focused near a convectively
influenced front across parts of the Plains into the Midwest and
Great Lakes.

..Dean.. 06/20/2025

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ACUS48 KWNS 210843
SWOD48
SPC AC 210842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Sat Jun 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
...D4/Tuesday...
Aside from some modest deamplification, little change to the
large-scale pattern is expected on Tuesday. An upper trough will
remain over the western CONUS, while an upper ridge persists over
the East.

Scattered to numerous thunderstorms will again be possible along the
western and northern periphery of the upper ridge, from the
central/southern High Plains into the Upper Midwest. Deep-layer flow
will generally be modest, but some severe threat could evolve in the
vicinity of an outflow-influenced front, in the presence of
favorable low-level moisture and moderate to strong buoyancy.

Farther east, a cold front is forecast to move southward across
parts of northern New England. Guidance varies regarding the extent
to which stronger deep-layer flow and large-scale ascent lag behind
the front, but moderate to strong buoyancy could support at least an
isolated severe threat during the afternoon and evening.

...D5/Wednesday...
Continued modest weakening of both the western trough and eastern
ridge is generally forecast on Wednesday. Scattered to numerous
thunderstorms will again be possible from the High Plains into the
Midwest, Great Lakes, and Northeast, along the periphery of the
ridge. Deep-layer flow is expected to be relatively weak across most
areas, but mesoscale corridors of somewhat greater severe threat
could evolve within this pattern.

...D6/Thursday - D8/Saturday...
Predictability of the large-scale pattern begins to notably decrease
by the end of next week. In general, an upper ridge may persist over
the Southeast, while one or more mid/upper-level shortwave troughs
move across the northern CONUS. This pattern may eventually yield an
increasing threat for organized severe storms across the northern Rockies/Plains and Upper Midwest, but details are very uncertain at
this forecast range.

..Dean.. 06/21/2025

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ACUS48 KWNS 240858
SWOD48
SPC AC 240857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Tue Jun 24 2025

Valid 271200Z - 021200Z

...DISCUSSION...
Models are in good agreement with the overall pattern through
Tuesday/D8, depicting a low-amplitude trough moving from the
northwestern states on Friday/D4 across the northern tier of states
and toward the Great Lakes by around Sunday/D6. This wave is then
forecast to amplify across Ontario/Quebec through the end of the
period, with cooler/more stable air pushing south with a cold front
from the Midwest into the Northeast.

Severe storms are currently forecast over parts of the Dakotas into
northwest MN on Friday/D4 as the stronger flow aloft interacts with
a moist and unstable air mass already in place. Damaging winds
appear the most likely mode of severe, along with sporadic large
hail as storms form during the afternoon within a surface trough,
and beneath increasing winds aloft. While severe storms may also
occur on Saturday/D5 over parts of the northern Plains or upper MS
Valley, predictability is lower given expected storms the previous
day and potential for long-lived convective systems. However, given
such strong instability forecast on Saturday/D5, a risk area is
likely to be issued in later outlook cycles over parts of the upper
Midwest/MS Valley.

Elsewhere, daily thunderstorms within the moist and unstable air
mass are forecast for the bulk of CONUS from the Plains eastward,
though in a generally weak shear environment. Portions of those
areas may see low/marginal probabilities as the events enter into
the Day 3 outlook time frame.

..Jewell.. 06/24/2025

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ACUS48 KWNS 250830
SWOD48
SPC AC 250829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Wed Jun 25 2025

Valid 281200Z - 031200Z

...DISCUSSION...
Models are in general agreement with the upper air pattern, but
increasing spread is seen from Sunday/D5 and beyond.

On Saturday/D4, a low amplitude wave will lift out of the
ND/northern MN vicinity and move into Ontario. This will result in
temporary height rises during the day before gradual falls occur
overnight and into as a secondary wave moves from MT into the
Dakotas overnight. Early day storms may exist over parts of northern
MN in association with the low-level jet, and this activity could
weaken during the day. Then, strong instability is forecast for
several models, perhaps MUCAPE to around 5000 J/kg, over eastern SD
and NE and into IA and MN. Heating within the surface trough may
spur afternoon development from SD into NE, with some potential for
activity to spread east/northeast. However, shear will likely be
weak, with 500 mb winds averaging around 15 kt. Despite very strong instability, the weak-forcing situation in the wake of the exiting
wave suggests low-predictability at this time.

Around Sunday/D5, the secondary wave is forecast to amplify across
the upper MS Valley and upper Great Lakes, with a cold front pushing
south and extending roughly from WI to NE. Strong instability will
likely exist ahead of such a boundary, though shear will again be
weak. Still, storms will likely develop across the region, with
areas of damaging gusts potential.

From Monday/D6 through Wednesday/D8, the aforementioned trough will
spread across the Great Lakes and Northeast, with what appears to be
an end to the extreme instability levels. Scattered storms will
likely persist over much of the Southeast and Mid Atlantic, with
sporadic strong gusts daily.

..Jewell.. 06/25/2025

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ACUS48 KWNS 260854
SWOD48
SPC AC 260852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Thu Jun 26 2025

Valid 291200Z - 041200Z

...DISCUSSION...
On the large scale, a low-amplitude upper trough over the northern
Plains on Sunday/D4 will amplify as it moves toward the upper Great
Lakes into Monday/D5, and more so into Tuesday/D6 when it will
stretch across into the Northeast.

At the surface, high pressure will extend into the northern to
central Plains on Sunday/D4, with a trough affecting the upper MS
Valley to central Plains. This trough/front will push farther south
on Monday/D5, extending roughly from the OH Valley into the southern
Plains, and eventually, into the Gulf Coast states into Wednesday/D7
as high pressure spreads into the MS Valley.

For the period, instability looks to be strongest on Sunday/D4 ahead
of the front from NE/KS into IA/MO/IL with upper 60s to lower 70s F
dewpoints common. While unstable, only weak westerly flow aloft will
be present, and this will likely result in south to southwest
propagating cluster of storms producing areas of gusty winds. Given
substantial storm coverage over much of the central Plains to
upper/middle MS Valley, predictability remains low for denoting
precise risk areas.

A low-end risk of severe storms with wind potential could develop
into the Mid Atlantic on Tuesday/D6 as the Great Lakes/Northeast
trough amplifies with westerlies increasing to 30 to perhaps 40 kt
at 500 mb. Otherwise, scattered storms will also occur away from
this boundary, across much of the Southeast as the moisture and
instability remain in place in a weak shear environment.

..Jewell.. 06/26/2025

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ACUS48 KWNS 270856
SWOD48
SPC AC 270855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Fri Jun 27 2025

Valid 301200Z - 051200Z

...DISCUSSION...
A mid-level trough will amplify across the Great Lakes at the
beginning of the period D4/Monday and shift into the Northeast by
Tuesday. A surface cold front will shift east across the Great Lakes
on Monday and to the Northeast and Mid-Atlantic on Tuesday. Moderate instability may develop across a large area east of the Appalachians
on Day 5/Tuesday. The strongest shear is forecast from Pennsylvania
northward, beneath the strongest mid-level flow. However, the
greatest instability should remain mostly south of this better flow.
Therefore, a favorable corridor may develop for some strong to
severe storms near the Mid-Atlantic/Carolinas where instability and
modest shear overlap, but this remains too uncertain for severe
weather probabilities at this time.

Beyond Day 5, mid-level ridging will shift east across the central
CONUS. At the surface, high pressure will build across much of the
eastern CONUS. The combination of weak mid-level flow beneath the
mid-level ridge and surface high pressure should limit severe
weather potential for Day 6 and beyond. Strong instability is
forecast to return to the northern Plains, but given the lack of
mid-level flow, any storms will likely only be marginally severe at
best. Some stronger mid-level flow may return to the northern Plains
by next weekend as the ridge starts to break down, which may be the
next chance for more organized severe storms in the latter portion
of the extended period.

..Bentley.. 06/27/2025

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ACUS48 KWNS 280801
SWOD48
SPC AC 280800

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CDT Sat Jun 28 2025

Valid 011200Z - 061200Z

...DISCUSSION...
A mid-level trough will move from the Great Lakes to the Northeast
on Day 4/Tuesday. At the surface, a cold front will move east
through the period. Moderate instability is expected along this
front and some severe weather may be possible from the Mid-Atlantic
to the Northeast. Slight risk (15%) probabilities may eventually be
needed within this zone, but there is potential for
cloudcover/thunderstorm activity from Monday evening to impact
destabilization. Therefore, confidence is not high enough for
probabilities at this time.

Beyond Day 4, a relative lull in severe weather potential is
expected. Multiple reinforcing mid-level troughs will amplify the
larger-scale trough across the eastern CONUS. As this occurs, the
surface cold front will move south, potentially to the Gulf Coast
and into the western Atlantic. This will eliminate the very moist
airmass which resulted in moderate to strong instability across much
of the eastern CONUS for the past few weeks.

The greater low-level moisture is expected to remain and perhaps
advect north across the central Plains beneath a large-scale ridge.
This could result in some thunderstorm activity, but shear is
expected to be very weak, and the building ridge aloft may suppress
convection on D5/Wednesday to D6/Thursday.

By next weekend, this ridge is expected to flatten with some
stronger mid-level flow moving across the northern Plains. The exact
evolution of the upper-pattern remains uncertain and therefore,
confidence is low, but severe weather chances may increase across
the northern Plains by next weekend.

..Bentley.. 06/28/2025

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ACUS48 KWNS 290820
SWOD48
SPC AC 290819

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CDT Sun Jun 29 2025

Valid 021200Z - 071200Z

...DISCUSSION...
The cold front which may result in severe weather on Day 3/Tuesday
will move into the Atlantic and near the Gulf Coast across Florida.
A reinforcing mid-level trough will maintain northerly flow across
the eastern CONUS as an area of high pressure builds into the
region. A drier, more continental airmass across the eastern CONUS
will keep severe weather chances minimal.

Upper 60s to low 70s dewpoints will remain across the Plains,
beneath a strong upper-level ridge. By the time the ridge starts to
break down on Day 6/Friday some severe weather is possible as a
mid-level trough moves into the northern Plains. However, the ECMWF
shows less than 20 knots of flow across the Plains. Therefore, shear
will likely be limited. Thunderstorms will be likely along the cold
front as it traverses the central and eastern CONUS next weekend.
However, the lack of stronger mid-level flow casts doubt on storm
organization. Therefore, no severe weather probabilities have been
added at this time.

..Bentley.. 06/29/2025

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ACUS48 KWNS 300855
SWOD48
SPC AC 300853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Jun 30 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A mid-level ridge will start the extended period across the Plains
on D4/Thursday. This ridge will shift east through the extended
period. A surface low will develop in the lee of the Rockies and
move slowly north and east, reaching eastern Ontario by D7/Sunday.
This surface low and its associated cold front will likely be the
only potential for any severe weather during the extended period.
However, at this time it appears the stronger shear will be well
displaced from the greater instability. Therefore, severe weather
probabilities are not necessary at this time.

Outside of this frontal zone during the Day 4 to Day 7 period,
thunderstorms are likely. However, weak lapse rates and very weak
shear is anticipated, with minimal storm organization.

..Bentley.. 06/30/2025

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ACUS48 KWNS 010902
SWOD48
SPC AC 010900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Tue Jul 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
A mid-level trough will traverse the Northern Plains and Upper
Midwest on Friday. This will likely be the most substantial severe
weather threat during the extended period before broad, strong
ridging builds across much of the eastern/central CONUS.

...Day 4/Friday...
As a positively tilted mid-level trough traverses the northern
Plains on Friday, strong southerly flow will advect moisture
northward across a broad warm sector near the Upper Midwest. This
will result in moderate to strong instability as temperatures warm
well into the 80s. Widespread thunderstorms are likely along the
frontal zone during the afternoon/evening. 35 to 40 knots of
mid-level flow will overspread the warm sector which will provide
some shear for storm organization. However, southwesterly surface
winds will also increase during the afternoon within the warm front
and therefore, the net shear may remain somewhat minimal. Some
organized storms with a threat for large hail and severe wind gusts
are possible, but the aforementioned concerns about deep-layer shear
preclude the confidence needed for 15% severe weather probabilities
at this time.

Beyond Day 4, moderate to strong instability is forecast across much
of the central and eastern CONUS with widespread thunderstorm
activity likely. However, shear will remain mostly nebulous with the
stronger mid-level flow confined to areas north of the better
instability. Therefore, some marginal regional severe weather threat
will be likely most days, but a more organized severe weather risk
appears unlikely at this time.

..Bentley.. 07/01/2025

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ACUS48 KWNS 020859
SWOD48
SPC AC 020857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Wed Jul 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
Some severe weather is possible on Day 5/Sunday and Day6/Monday
across portions of northern Montana and North Dakota as moderate
instability builds into the area with moderate mid-level flow
southeast of a trough across western Canada. The evolution and
timing of this trough remains uncertain and therefore, no severe
weather probabilities will be added at this time.

Beyond this timeframe, moderate to strong instability is forecast
across much of the central and eastern CONUS for much of the
extended forecast period with widespread thunderstorm activity
likely. Despite this storm coverage and instability, organized
severe weather seems unlikely given mostly weak deep-layer
shear/flow.

..Bentley.. 07/02/2025

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ACUS48 KWNS 030859
SWOD48
SPC AC 030858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
During the extended forecast period, a mid-level ridge will build
across the InterMountain West. Aside from the primary ridge, there
will be several mid-level shortwave troughs throughout the flow
across the Northwest and also from the Great Lakes to the Atlantic
coast. Widespread thunderstorm activity is expected throughout the
period, but stronger mid-level flow/shear should mostly stay north
of the stronger instability early in the period.

At some point next week (mid week according to the GFS and late next
week into the weekend ECMWF) mid-level northwesterly flow will
likely strengthen across the Plains (to the east of the primary
ridge). Whenever this occurs, the pattern would favor severe MCSs
given the forecast strong instability and moderate deep-layer shear.
However, the uncertainty in the upper-level pattern remains too
great to provide an accurate forecast of the timing and location of
the greatest severe weather threat toward the middle to late part of
next week.

..Bentley.. 07/03/2025

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ACUS48 KWNS 040842
SWOD48
SPC AC 040841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Fri Jul 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
An upper ridge will gradually build over the Southwest while mainly
zonal mid-level flow persists over the northern CONUS through next
week. A relatively nebulous surface pattern will be the norm through
the extended range. Rich low-level moisture will overspread the
CONUS east of the Rockies Days 4-8/next Monday-Friday, supporting
scattered thunderstorm development over much of the Great Plains
into the MS Valley, and the Southeast into the Northeast. The best
chance for at least isolated strong to potentially severe storms in
the upcoming week would be across the north-central CONUS. Here, the
low-level moisture will advect northward beneath relatively cooler
temperatures and modest northwesterly flow/shear aloft. However,
given the nebulous and weakly forced environment, confidence is too
low to delineate severe probabilities over the north-central U.S.
for any given day.

..Squitieri.. 07/04/2025

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ACUS48 KWNS 050848
SWOD48
SPC AC 050846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Sat Jul 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
An upper ridge will build across the Southwest and remain in place
this upcoming week into next weekend. Relatively zonal mid-level
flow will persist over the northern CONUS through the extended
forecast period, with multiple embedded impulses expected to track
eastward within the zonal flow. As the mid-level impulses traverse
the northern Plains, isolated strong to severe storm development
will be possible given the presence of ample buoyancy. However,
there are appreciable differences in the placement and timing of
these impulses among medium-range guidance members. Therefore,
severe probabilities have been withheld since confidence is
currently low regarding where and when organized clusters of severe
storms will develop.

..Squitieri.. 07/05/2025

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ACUS48 KWNS 060830
SWOD48
SPC AC 060829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Sun Jul 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
An upper ridge will remain in place across the Southwest while zonal
mid-level flow continues to support embedded impulses traversing the
northern CONUS this week into next weekend. The first notable
mid-level impulse, which will bring severe potential to the central
U.S. in the Days 2-3 time-frame, will approach the East Coast while
slowing its forward advance. The impulse should reach the East Coast
by Day 4 (Wednesday), providing adequate lift for at least scattered thunderstorms through the remainder of the week. Given preceding
rich low-level moisture, ample buoyancy will be available to support
at least isolated strong storms with potentially damaging gusts.

A more pronounced mid-level trough will approach the Northern Plains
in the Days 4-5 (Wednesday-Thursday) period, resulting in strong
surface troughing and the northward advection of rich low-level
moisture. Medium range guidance consensus shows that strong
instability will precede the upper/surface troughs, favoring the
development of severe storms. The first chance for severe storms
will be over the western Dakotas on Wednesday as the upper trough
approaches from the Northern Rockies. Upper support in this region
does not currently appear robust, so severe storms may occur on a
more isolated basis (hence no severe probabilities introduced at
this time). However, there is medium range guidance agreement in the
upper trough ejecting into the northern Plains on Day 5 (Thursday),
with some guidance suggesting that instability could become extreme.
Though it is difficult to confidently pinpoint storm mode this far
in advance, guidance hints at the development of a persistent,
elongated convective system, which may be capable of supporting all
severe hazards, especially severe winds. Severe probabilities have
been added to address this scenario.

As the pronounced mid-level trough progresses eastward, more
organized severe storms are possible over the MS Valley and perhaps
points east Day 6 onward. However, the intensity, coverage, and
location of severe potential will be highly dependent on the
evolution of convection from previous days, which is hard to know
this far in advance. Therefore, severe probabilities have been
withheld this outlook.

..Squitieri.. 07/06/2025

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ACUS48 KWNS 070844
SWOD48
SPC AC 070842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Mon Jul 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
The Southwest upper ridge will gradually flatten as a more
progressive mid-level flow regime becomes established over the
northern CONUS later this week into early next week. Multiple
pronounced mid-level troughs, with cooler temperatures aloft, will
traverse the north-central U.S. and overspread rich low-level
moisture. Strong buoyancy will precede these troughs, and upon
lifting of this unstable airmass, at least scattered organized
thunderstorm development should ensue, with multiple rounds of
strong to severe storms possible.

...Day 4 (Thursday) - Northern Plains...
The first in a series of mid-level troughs will eject into the
northern Plains on Day 4/Thursday, encouraging surface lee troughing
across the central and northern Plains. Dewpoints into the 70s F,
beneath 8+ C/km mid-level lapse rates, will support strong to
locally extreme instability by afternoon peak heating. The ejection
of the upper trough will provide enough upper support for scattered thunderstorm development. Increasing westerly flow with height will
result in straight, elongated hodographs. Supercells should be the
main mode of convection, at least initially, with severe wind and
hail the primary threats.

...Days 5-6 (Friday-Saturday) - Midwest toward the Great Lakes...
The main mid-level trough will continue to slowly approach the Upper
MS Valley as a preceding mid-level impulse continues to advance
eastward. Potential exists for renewed thunderstorm development for
portions of the Upper MS Valley and Midwest on Friday, spreading
east with upper trough advancement toward the Great Lakes on
Saturday. Rich low-level moisture beneath steep mid-level lapse
rates will promote strong instability in the warm sector, amid
modest vertical wind shear. Somewhere in this region, strong to
severe storms are likely, with severe wind/hail the main concerns on
both Friday and Saturday. The timing and location of thunderstorm
initiation will be highly dependent on the position of remnant
outflow boundaries from storms during previous days. Such details
are quite challenging to point out this far in advance, precluding
severe probabilities at this time, though probabilities will likely
be needed in future outlooks.

...Days 7-8 (Sunday-Monday) - Upper Mississippi Valley...
The next in a series of mid-level troughs will traverse the
north-central CONUS toward the end of the period. Medium-range
guidance consensus depicts extreme instability (i.e. well over 4000
J/kg MLCAPE) preceding this trough, along with strong enough
westerly mid-level flow and accompanying vertical wind shear. As
such, another episode of organized severe storms is possible in the Sunday/Monday time-frame. However, given the seasonal weak forcing
associated with this second low-amplitude trough, run-to-run
guidance consistency is desired before severe probabilities are
delineated.

..Squitieri.. 07/07/2025

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ACUS48 KWNS 080818
SWOD48
SPC AC 080817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Tue Jul 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
The overall current large-scale pattern will persist through this
forecast period, albeit with minor day-to-day variations. More
specifically, a mid-level ridge will persist across the western US,
although its center will meander from the Southwest US to off the
coast of California and back; a series of shortwave troughs of
varying intensity will quickly move across the northern Plains; and
a very warm, moist environment will remain entrenched across the
eastern US.

This overall pattern suggests episodic bouts of severe thunderstorms
on any given day. However, the timing and location of specific
episodes will be tied to mesoscale details and impacts from prior
days' convection which have low predictability on time scales of
this forecast period. As such, low confidence in the details of
required to identify any of these severe events currently precludes
any probabilistic delineation at this time.

That said, there are a couple of scenarios being monitored for
potential future highlights. The first is the potential for severe
storms across the southern Plains on Saturday or Sunday associated
with a residual boundary/front. However, impacts from a potential
overnight mesoscale convective system moving from the High Plains
into the Southern Plains on Friday night into Saturday lead to
little confidence in the placement of any boundaries and the
resulting severe potential.

Another potential is for severe convection across northern Minnesota
and the Upper Great Lakes early next week associated with a stronger
shortwave trough moving through southern Canada. However, guidance
continues to show high variance regarding the strength of moisture
return, degree of instability, and timing of the shortwave itself to
preclude unconditional severe probabilities at this time.

..Marsh.. 07/08/2025

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ACUS48 KWNS 090820
SWOD48
SPC AC 090818

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0318 AM CDT Wed Jul 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
The overall large-scale pattern looks to remain characterized by mid-to-upper-level ridging across the western United States with a
zonal to broadly cyclonic flow across the northern tier of the US
through the forecast period. At the same time, rich/moist low-level
moisture looks to remain entrenched across much of the eastern US,
sustained in part by broad, southerly flow, albeit with some
fluctuations in raw values. Global models continue to be bullish on
a seasonably strong cold front pushing south through much of the
central US late in the forecast period, ushering in a cooler/drier
airmass.

Strong-to-locally severe thunderstorms will be possible somewhere
across the eastern CONUS every day of the forecast period. However,
with synoptic-scale forcing/dynamics primarily constrained to
Canada, most thunderstorms will be determined by
sub-synoptic/mesoscale details dictated by/reinforced with each
prior day's convection. Thus, confidence is too low in any one
location on any given day to introduce unconditional severe
probabilities at this time.

However, some areas/scenarios of interest to monitor include the
southern Great Plains on Days 4-5/Saturday-Sunday as a moist, weakly
capped environment will exist in proximity to an increasing diffuse
surface boundary. Other areas include the East Coast most afternoons
and the along and ahead of seasonably strong cold front pushing
south through the Great Plains from Days 6-8.

For each of the areas of interest/scenarios of interest above, weak effective-layer shear stemming from generally weak tropospheric flow
will be a limiting factor for a more organized severe potential and
confidence to introduce unconditional probabilities.

..Marsh.. 07/09/2025

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ACUS48 KWNS 100818
SWOD48
SPC AC 100816

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Thu Jul 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
At the start of the forecast period, the mid-level pattern will
generally be zonal across much country, with the greatest height
gradient found across the northern United States. By the middle of
next week, a short-wave trough moving within the broader flow regime
will amplify the height field across the northern Rockies before
moving into the central US. The overall pattern recognition would
suggest the potential for at least isolated severe thunderstorms
ahead of this feature across then northern Plains into the Upper
Great Lakes. However, model run-to-run timing differences along with inter-model timing differences precludes the ability to identify 15% unconditional probabilities on any given day.

Associated with the aforementioned mid-level trough, a surface-cold
front will push south through much of the Plains and into the East.
Additional thunderstorms will be likely along the front, however,
the location of the front on any given day will be strongly
influenced by previous days' convection. As such, when coupled with
the uncertainty in the timing of any mid-level wave, predictability
is too low to identify unconditional probabilities at this time.

..Marsh.. 07/10/2025

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ACUS48 KWNS 110841
SWOD48
SPC AC 110840

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0340 AM CDT Fri Jul 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
A surface cold front across the southern Great Plains early in the
period will quickly redevelop northward into the northern Plains in
response to strong lee cyclogenesis across the northern High Plains.
This cyclogenesis will occur in response to a positive-tilt
short-wave trough moving through the broadly zonal mid-level flow
across the northern US.

This front will move back south during the period as a seasonably
strong high pressure builds southward into the central US in the
wake of the aforementioned short-wave trough. Thunderstorms are
likely to develop in the vicinity of the front/aggregate outflow
boundary each afternoon as it moves south. However, given the lack
of significant flow amplification as the mid-level wave crosses the
northern US, it is likely that thunderstorms will remain displaced
south of the requisite effective-layer shear needed to promote an
organized severe threat identifiable at this time range.

One exception to the idea that storms will be displaced from the
better shear may take place on Monday/Day-4 across portions of North
Dakota. Here, low-level moisture will surge northward in response to
the aforementioned northern High Plains lee cyclogenesis. Steep
mid-level lapse rates will overspread the northern Great Plains
during the day, yielding most-unstable CAPE values ranging from 1000
J/kg to perhaps 3000 J/kg depending on model guidance.

However, run-to-run inconsistency in the space and time evolution of
relevant features leads to little confidence in identifying where
any overlap of thunderstorms, instability, and effective-layer shear
might support severe thunderstorms. However, if model guidance
begins to converge on potential scenarios, probabilistic delineation
may become warranted in subsequent forecasts.

..Marsh.. 07/11/2025

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ACUS48 KWNS 120731
SWOD48
SPC AC 120730

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sat Jul 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
Several shortwave impulses are forecast to move through
low-amplitude upper troughing over the northern tier of the U.S.
during the Day 4-8 period. At the surface, a cold front is expected
to develop south/southeast across portions of the northern/central
Plains and Upper Midwest on Days 4-5/Tue-Wed. Given a moist and
unstable airmass ahead of this feature, some severe potential is
possible from the central Plains to the Upper Midwest. However,
medium range guidance shows large spread in the location and timing
of the front and any associated convection, resulting in low
predictability.

Later in the period, strong upper ridging will develop over the
Southeast. Some severe potential could continue eastward across the
Great Lakes to the Mid-Atlantic around Days 5-6/Wed-Thu as the
aforementioned cold front stalls in response to the building
Southeast ridge. However, large-scale ascent and deep-layer flow
will remain modest, and any severe potential would likely be driven
by mesoscale processes not well resolved at this time scale.

..Leitman.. 07/12/2025

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ACUS48 KWNS 130734
SWOD48
SPC AC 130732

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0232 AM CDT Sun Jul 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
Generally low-amplitude westerly flow will persist across the
northern tier of the CONUS during the Day 4-8 period. A couple of
shortwave impulses will migrate through westerly flow from the Upper
Midwest to the Great Lakes vicinity on Days 4-5/Wed-Thu and again
during the weekend. These features could support some severe
thunderstorm potential for parts of the Midwest/Great Lakes
vicinity, particularly on Days 4-5/Wed-Thu as a sagging cold front
stalls over the Great Lakes. However, prior convection and large
spread among various medium range guidance regarding timing and
location of these somewhat subtle features precludes severe
probabilities at this time.

Strong upper ridging will develop across the south-central and
southeast U.S. beginning around Day 6/Fri. Weak deep-layer flow
beneath the upper ridge and lack of large-scale forcing will limit
severe potential from the southern Plains into the Southeast.

..Leitman.. 07/13/2025

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ACUS48 KWNS 140830
SWOD48
SPC AC 140829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Mon Jul 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Upper ridging will build across the south-central and southeastern
U.S. during the Day 4-8 period. This will confine a series of
low-amplitude upper troughs to the northern tier of the U.S. along
the international border. Bouts of strong to severe thunderstorm
potential will be possible through the period as individual
shortwaves provide modestly enhanced mid/upper westerly flow from
the northern Plains to the Great Lakes vicinity. Given the generally low-amplitude nature the upper pattern across the northern U.S.
through at least Day 6 or 7/Sat or Sun, the main driver of severe
potential each day will be mesoscale features tied to prior days
convective evolution, not well resolved at longer time scales. As a
result, predictability is low.

..Leitman.. 07/14/2025

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ACUS48 KWNS 150653
SWOD48
SPC AC 150652

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0152 AM CDT Tue Jul 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
Low-amplitude/zonal westerly mid/upper flow is forecast across the
northern U.S. for much of the Day 4-8 period. At the same time, the
subtropical upper ridge/high over the Southeast will spread
westward, with larger-scale upper ridging developing over the
central U.S. late in the forecast period. Seasonally moist and
unstable conditions will exist for much of the CONUS east of the
Rockies. This will lead to daily thunderstorm activity, particularly
for parts of the northern/central Plains to the Midwest and
Mid-Atlantic regions. These areas will generally be on the north
side of the subtropic high and the southern fringes of any stronger
westerly flow near the international border. However, a lack of any
stronger forcing for ascent or notable surface features precludes
severe probabilities.

..Leitman.. 07/15/2025

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ACUS48 KWNS 200847
SWOD48
SPC AC 200845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Sun Jul 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
The latest medium-range output offers little change from prior runs
concerning the general large-scale pattern evolution during the
middle to latter portion of the coming work week. It still appears
that a fairly significant mid-level low currently emerging from the northwestern Canadian Arctic latitudes will slowly progress across
and east-southeast of the Hudson Bay vicinity, to the north of an
increasingly prominent mid-level high evolving across the Ohio
Valley. As this contributes to a belt of strengthening westerly to northwesterly flow between the two features, it appears that
low-level moistening in a corridor beneath the southern periphery of
this regime will support substantive destabilization, and increasing
potential for organized strong to severe thunderstorm development.

The extent to which this corridor evolves south of the international
border, across parts of the Upper Midwest and adjacent Great Lakes
region toward the St. Lawrence Valley/New England remains at least a
bit unclear. Adding to this uncertainty, forcing for this potential
convective development will be largely associated with sub-synoptic perturbations with low predictability at this extended time frame.

..Kerr.. 07/20/2025

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ACUS48 KWNS 160747
SWOD48
SPC AC 160745

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 AM CDT Wed Jul 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
A low-amplitude upper trough will move from the Great Lakes through
the Northeast during the Day 4-5/Sat-Sun period. Some enhanced
westerly flow aloft and a deepening surface low will accompany this
system. While forecast guidance varies with timing and location of
these features, some severe potential could develop from portions of
the Great Lakes to the Northeast/Mid-Atlantic over the weekend ahead
of a cold front. Details are still uncertain regarding where a
better chance for severe storms may develop, precluding
probabilities.

By early next week, upper ridging is forecast for much of the CONUS
east of the Rockies while an upper shortwave trough persists over
the Northwest. Late in the period, a shortwave impulse may eject
from the Northwest upper shortwave and move across the northern
Plains, posing some increasing risk for severe potential, though
confidence in this scenario remains too low to include an outlook
area at this time.

..Leitman.. 07/16/2025

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ACUS48 KWNS 170732
SWOD48
SPC AC 170731

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0231 AM CDT Thu Jul 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
Upper ridging will build across much of the CONUS during the Day 4-8
period. However, progressive, but low-amplitude westerly northern
stream flow will continue atop the upper ridge across the northern
tier of the U.S. This overall pattern will favor bouts of strong to
severe thunderstorms within west/northwesterly flow aloft from the
northern Plains into portions of the Midwest. However, given subtle
forcing mechanisms, this activity will be driven by mesoscale processes/features (MCVs from prior convection, modifying outflow
boundaries, etc) that are more uncertain at longer forecast times.
As such, predictability is too low for delineating areas at this
time.

..Leitman.. 07/17/2025

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ACUS48 KWNS 180855
SWOD48
SPC AC 180854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Jul 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
Medium-range guidance suggests that mid/upper ridging may remain a
prominent influence across much of the central and southeastern U.S.
through this period. Beneath its northern periphery, across parts
of the northern Great Plains into Upper Midwest and Great Lakes/Ohio
Valley, it appears that a seasonably moist boundary-layer may become characterized by moderate to strong diurnal destabilization each
day. However, forcing for ascent to support convective development
remains unclear, and might be largely dependent on sub-synoptic
features with low predictability, particularly at this extended
range.

Sizable spread exists among the output concerning synoptic features
within the westerlies, as well. However, there appears some signal
that a short wave perturbation, emerging either from the Pacific
Northwest or northwestern Canadian provinces early next week, could
be accompanied by an eastward advecting plume of elevated
mixed-layer air, low-level moistening and strengthening
lower/mid-tropospheric wind fields across parts of the Upper
Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late
next Wednesday into Friday. It might not be out of the question
that this regime could become supportive of one or two sustained,
organized clusters of storms capable of producing swaths of damaging
winds and some hail.

..Kerr.. 07/18/2025

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ACUS48 KWNS 190848
SWOD48
SPC AC 190847

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Sat Jul 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
Medium-range guidance continues to indicate a belt of strengthening west-northwesterly flow across Ontario, Quebec and adjacent portions
of the U.S. Upper Midwest/Great Lakes toward the St. Lawrence Valley
and Northeast during the middle to latter portions of the coming
work week. This is forecast to occur as a notable mid-level low,
digging southeast of the Canadian Arctic latitudes over the next
couple of days, accelerates east-southeast of the Canadian Northwest Territories through the Hudson Bay vicinity and northern Quebec, to
the north of an increasingly prominent high becoming centered over
the Ohio/Tennessee Valleys by next Wednesday/Thursday.

Potential forcing for ascent associated with smaller-scale
perturbations emerging from initial troughing across the Pacific
Northwest, or other more subtle perturbations migrating around the
northwestern periphery of the high, before progressing eastward
along the southern periphery of this regime remain much more
unclear. However, guidance remains suggestive that moistening
beneath a plume of eastward advecting elevated mixed-layer air might
become supportive of destabilization conducive to the evolution of
progressive organized clusters of storms capable of producing swaths
of strong to severe gusts, in the presence of favorable shear.

..Kerr.. 07/19/2025

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ACUS48 KWNS 210854
SWOD48
SPC AC 210853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Jul 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
Medium-range models indicate that mid-level ridging, initially
centered over the Ohio Valley, will weaken late this work week
through next weekend, as flow undergoes substantive amplification
upstream. This appears likely to include a significant short wave
trough digging southeast of the Aleutians, accompanied by lower/mid-tropospheric cyclogenesis across the northeastern Pacific.
Part of a higher latitude blocking pattern, little subsequent
movement of this cyclone is forecast through early next week, as an
expansive, prominent mid-level ridge also evolves in the downstream
lower latitudes, across much of the Intermountain West, Rockies and
Great Plains into mid and lower Mississippi Valley.

However, as a notable mid-level low continues slowly east of Hudson
Bay, across northern Quebec and Newfoundland and Labrador, a belt of
seasonably strong westerly mid/upper flow may be maintained across
Ontario and Quebec this Thursday through Friday. Along the
favorably sheared southern fringe of this regime, seasonably moist
low-level air advecting ahead of a stalled to southward advancing
frontal zone may contribute to sufficient destabilization for the
evolution of organizing thunderstorm clusters capable of producing
swaths of damaging wind gusts. The extent to which this may impact
U.S. portions of the Great Lakes into New England remains unclear.

It might not be out of the question that a similar type regime could
evolve beneath developing northwesterly mid-level flow, from the
North Dakota/Minnesota international border area into the Upper
Midwest/Great Lakes late next weekend into early next week. Current
guidance is still suggestive that this is a lower probability, but
this could be due to the low predictability of the pertinent
features at this extended range.

..Kerr.. 07/21/2025

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ACUS48 KWNS 220852
SWOD48
SPC AC 220850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Tue Jul 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
Medium-range guidance suggests that strongest destabilization
(including large potential instability) by next weekend into early
next week will become focused once again from the lee of the
northern U.S. Rockies across and northeast of the middle and lower
Missouri Valley into Upper Midwest. This is forecast to be
supported by seasonably high boundary-layer moisture content,
beneath a plume of steepening mid-level lapse rates near the
southwestern periphery of an increasingly northwesterly regime,
between building mid-level ridging along/east of the Rockies and
another significant low digging southeast of the central Canadian
Arctic latitudes through Hudson Bay.

By next Sunday into Monday, it appears possible that this
environment could become supportive of the evolution of one or two
organizing, east-southeastward propagating convective systems.
However, the forcing for any such development remains unclear, and
probably will be tied to sub-synoptic perturbations with very low predictability at this extended range.

..Kerr.. 07/22/2025

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ACUS48 KWNS 230901
SWOD48
SPC AC 230900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Jul 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
Medium-range guidance continues to indicate that initially zonal
westerlies near the central Canadian/U.S. border will undergo
considerable amplification by the early to middle portion of next
week. This is forecast to occur as a significant mid-level low digs
southeast of the Aleutians, before gradually pivoting eastward and northeastward across the northeastern Pacific. To the east of
building downstream ridging across the Canadian Prairies, another
significant low emerging from the Arctic is forecast to dig into and
across the Hudson Bay vicinity. Before broad cyclonic flow to the
south of this latter feature encompasses much of the Upper Midwest
and Great Lakes through Northeast by the end of the period, a
prominent mid-level high may redevelop west-northwest of the
Southeast through central Great Plains.

As this regime evolves, it appears that a plume of elevated
mixed-layer air emerging from the Intermountain West will contribute
to steepening mid-level lapse rates across parts of the northern
Great Plains, then eastward and southeastward beneath increasingly northwesterly mid-level flow across the Upper Midwest/Great Lakes
and parts of the Ohio Valley. Beneath this regime seasonably high boundary-layer moisture content northeast of the middle and lower
Missouri Valley likely will contribute to moderate to strong
potential instability.

Based on the latest ECENS and GEFS, rising mid-level heights are
forecast within broadly anticyclonic flow across the northern Great
Plains and Upper Midwest, through the international border vicinity,
on Saturday. There appears a general signal that a subtle
perturbation may progress through this regime, across the
Minnesota/Wisconsin vicinity, Sunday through Sunday night. As it
does, the environment could become potentially conducive to the
evolution of a substantive organized convective system, before
mid-level heights begin to gradually fall across the upper Great
lakes into Upper Midwest during the early to middle portion of next
week. This could be accompanied by continuing potential for renewed
strong to severe thunderstorm development, with a tendency to
propagate eastward and southeastward into the Ohio Valley and
possibly parts of the Northeast. However, much of this may
significantly depend on interacting sub-synoptic developments with
low predictability in the extended range.

..Kerr.. 07/23/2025

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ACUS48 KWNS 240900
SWOD48
SPC AC 240858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
Models indicate substantive amplification within an initially zonal
belt of westerlies across the northern mid-latitude Pacific during
the coming days, with several embedded closed lows evolving,
including one by the beginning of the period across the northeastern
Pacific, on the leading edge of an increasingly blocked regime.
Downstream, as another significant low, emerging from the Arctic
latitudes, turns across the eastern Northwest Territories into and
through Hudson Bay, mid/upper ridging is forecast to build through
much of the Canadian Prairies. Gradually, models indicate that
amplified ridging will encompass much of interior North America,
across and east of the Rockies through the mid to latter portions of
next week, while amplified troughing evolves further downstream,
across the eastern Canadian provinces, the Great Lakes and
Northeast.

The evolution of this regime appears likely to be accompanied by a
plume of steepening mid-level lapse rates overspreading the northern
U.S. Great Plains and adjacent portions of southern Canada, toward
the Upper Midwest/Great Lakes, during the early to middle portion of
next week, before becoming suppressed southwestward. Aided by the
return of seasonably high boundary layer moisture content to areas
near and northeast of the lower through middle Missouri Valley, it
appears that this will contribute to a broad area of moderate to
large potential instability.

This environment may become conditionally supportive of the
evolution of longer-lived organized thunderstorm clusters, with
potential to produce swaths of damaging wind gusts across parts of
the northern Great Plains, Upper Midwest and Great Lakes into the
Ohio Valley and perhaps parts of the Northeast. However, prior to
more substantive mid/upper trough amplification, and the southward
advancement of a cold front into much of the northeastern U.S. by
the middle of next week, the evolution of any such cluster, south of
the international border, will likely largely depend on subtle short
wave perturbations progressing through the larger scale ridging.
Given the low predictability of these features at this extended
range, and the uncertain impacts of their associated convection and
outflow on subsequent destabilization, severe probabilities remain
low due to the uncertainties.

..Kerr.. 07/24/2025

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ACUS48 KWNS 250856
SWOD48
SPC AC 250855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Fri Jul 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
The strongest mid-level flow will move from the Upper Midwest into
the Northeast this weekend into the middle of next week. As this
occurs, a surface boundary will slowly sag into the central Plains
and Ohio Valley. Given the very moist airmass to the south of the
boundary, strong to potentially severe storms are possible along the
boundary at least into the middle of next week. With the stronger
flow/shear displace north of the boundary and model differences in
the location, uncertainty remains too high for highlights.

Farther west, moisture will be pushed up against parts of the
northern Rockies and adjacent High Plains. Between the terrain and
shortwave troughs moving through the central U.S. ridge, it is
possible strong to severe storms could develop and progress along
the surface boundary into greater areas of moisture/buoyancy in the
Plains. Given the dependency on the low-predictability shortwaves,
it is not clear where the greatest risk will be from the High Plains
into the Plains through the middle of next week.

By the end of next week, model guidance suggests a general trend of
continued upper ridge building into Plains. Stronger mid-level winds
will remain in parts of the Northeast with additional shortwave
perturbations moving through parts of the northern Rockies. Severe
risk along the boundary should decrease as it becomes further
removed from the stronger flow. Though predictability is low
regarding the shortwave troughs, some severe risk could develop in
parts of the northern Rockies.

..Wendt.. 07/25/2025

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ACUS48 KWNS 260853
SWOD48
SPC AC 260852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Sat Jul 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
The upper-level pattern over the next week will generally feature an
elongated upper ridge centered over the Southeast stretching into
the Northwest. In the Northeast and nearby vicinity, upper-level
cyclonic flow will be present. A belt of stronger mid-level winds
will accompany that trough. Along the West Coast, a lower amplitude
shortwave trough will slowly move northward along the coast. As the
Northeast trough continues to shift east into late next week and the
weekend, the surface cold front will continue to be pushed
southward. Thunderstorms are likely to occur along and near this
boundary given the hot and moist airmass to its south. While some
severe risk could accompany this activity, stronger mid-level flow
will become displaced farther and farther northward from the
boundary each day. This leads to uncertainty in the overall
magnitude of the severe threat from the Ohio Valley into the Mid-South/Southeast.

Additional storms, with some severe potential could occur in parts
of the Northwest with the approach of greater mid-level moisture and
the trough. Again, the placement and intensity of this activity is
uncertain. Even with a decrease in low-level moisture behind the
surface front, remaining moisture will be pushing into the terrain
of the northern Rockies. Along with some mid-level flow enhancement,
strong to severe storms would be possible.

..Wendt.. 07/26/2025

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ACUS48 KWNS 270828
SWOD48
SPC AC 270827

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CDT Sun Jul 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
The general upper-level pattern over the next week will feature a
trough in the Northeast, a ridge over much of the southern U.S. and
Plains, and a weak trough off the West Coast. The Northeastern
trough will weaken with time, before moving out of the region around
next weekend. Models eventually develop a shortwave trough in the
West, but this signal has been inconsistent in the past several
runs. At the surface, high pressure will build into the Great Lakes
and Northeast. This will progressively push a cold front farther
south and west with time.

While some severe risk is possible along the cold front, shear and
buoyancy will be diminished with each successive day. With the front
pushing modest moisture into the Rockies, convection is possible
each day next week. Strong to potentially severe storms may occur
with this activity, but weak shear beneath the upper ridge makes it
unclear where the most intense storms would be. Furthermore,
repeated days of convection will at some point adversely affect the
quality of the low-level airmass. Predictability remains too low for highlights.

..Wendt.. 07/27/2025

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ACUS48 KWNS 280850
SWOD48
SPC AC 280849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Mon Jul 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
By late next week, the upper-level trough in the Northeast will be
moving into the Canadian Maritimes. In its wake, high pressure at
the surface will build into the Upper Midwest/Ohio Valley. This will
push the surface front farther south each day through the weekend.
In the West, cyclonic flow will tend to weaken over time. The
surface front will be pushed up against the Rockies. Model guidance
shows progressively lower amounts of buoyancy south of the front in
the Southeast, likely due to repeated days of convection. This
activity will also become farther removed from stronger shear. Winds
with some upslope component with weak/modest westerlies aloft could
allow for some severe risk near the Rockies and adjacent High
Plains, but the overall weak shear and potential for sequential
convective days leading to a poor quality airmass suggest the threat
is like to remain marginal. Predictability of organized severe
weather remains low.

..Wendt.. 07/28/2025

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ACUS48 KWNS 290856
SWOD48
SPC AC 290855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Tue Jul 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
Surface high pressure will build into the eastern CONUS this weekend
which will push a cold front south to near the Gulf Coast. Limited
instability in the wake of this front should limit severe weather
potential for many areas east of the Plains. As the upper-level
ridge weakens across the Plains by the end of the weekend, more
zonal flow across the Mountains will lead to weak lee troughing. Southerly/southeasterly flow will result in some instability across
the High Plains. Mid-level flow will not be that strong, but should
be sufficient for some isolated severe weather potential. However, predictability decreases significantly once the ridge breaks down
and therefore, it is unclear when or where a more organized severe
weather threat may occur.

..Bentley.. 07/29/2025

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ACUS48 KWNS 300844
SWOD48
SPC AC 300842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Jul 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
Surface high pressure will build into the eastern CONUS this weekend
and usher in an extended period of cooler and less humid weather for
much of the eastern CONUS with reduced severe weather chances. Some
severe weather chances will remain from the central High Plains to
the northern Plains where low-level moisture is expected to remain.
Several weak embedded mid-level shortwave troughs may result in some thunderstorm activity from the central to northern High Plains amid
moderate to strong instability. A few severe storms are possible
early next week with any of these passing troughs.

There is some signal that a more organized severe weather threat
could materialize by the middle of next week as strong instability
builds across the northern Plains and stronger mid-level troughing
and flow becomes more prevalent across the region. However,
predictability is low within this low-amplitude pattern. There is
not much consensus for the overall pattern beyond D6/Monday and
therefore, no severe weather probabilities are warranted at this
time.

..Bentley.. 07/30/2025

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ACUS48 KWNS 310909
SWOD48
SPC AC 310908

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0408 AM CDT Thu Jul 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
The extended range will primarily feature the potential for
Northwest flow severe across the Plains. Moderate to strong
instability is expected to build across the central Plains and into
parts of the northern Plains. A mid-level trough off the California
coast at the beginning of the period is forecast to move northward
and eventually into southern Canada. Beyond this time, the forecast
uncertainty increases. Both the ECMWF and GFS suggest some troughing
will advance toward the Midwest/Great Lakes, but the amplitude
varies. This will have significant impact on the potential locations
of severe weather and the potential for the threat to extend east of
the Plains/Upper Midwest. Regardless of the exact solution of the
extended range pattern, moderate mid-level flow will likely
overspread much of the northern Plains and potentially portions of
the central Plains. Where this mid-level flow interacts with the
developing instability and thunderstorms, some severe weather is
possible. However, the uncertain timing and evolution of the pattern
makes identification of these corridors challenging and precludes
severe weather probabilities at this time.

..Bentley.. 07/31/2025

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ACUS48 KWNS 010854
SWOD48
SPC AC 010852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Fri Aug 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
Early in the week, a mid-level trough is forecast to remain over the Mississippi Valley, as a ridge builds northward across the High
Plains. To the east of the ridge, moderate to strong instability is
forecast to develop Monday afternoon over parts of the High Plains.
Isolated severe storms that form near the instability axis could
pose a severe threat from the afternoon into the evening, but
limited large-scale ascent should keep any severe threat localized.

On Tuesday, a shortwave mid-level trough is forecast to move through
the northern High Plains. Thunderstorms that form ahead of the
trough in the afternoon could be associated with an isolated severe
threat. The models suggest that this feature will move into northern
Plains Tuesday night into Wednesday. This could result in scattered thunderstorm development early in the day on Wednesday over parts of
the eastern Dakotas. The trough is forecast to exit the region by
Wednesday afternoon. In the wake of the trough, isolated
thunderstorm development could re-develop across the northern Plains
late Wednesday afternoon into the evening. These storms could be
associated with isolated severe gusts and hail.

...Thursday/Day 7 and Friday/Day 8...
On Thursday, a shortwave trough is forecast to move into the
northern Plains. Ahead of the trough, a moist and unstable airmass
should be in place by afternoon. Some model solutions suggest that a
convective cluster will develop Thursday evening over parts of the
eastern Dakotas, with the storms moving east-southeastward into the
upper Mississippi Valley during the overnight period. Considering
that moderate deep-layer shear is forecast, these storms would be
associated with a threat for hail and severe wind gusts. However, predictability at this extended range is low, mainly due to issues
concerning the trough timing and parameter magnitudes.

A severe threat will again be possible on Sunday across parts of the
northern Plains, as a mid-level trough develops and approaches the
region. On Sunday, predictability again is low due to similar
issues.

..Broyles.. 08/01/2025

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ACUS48 KWNS 012112
SWOD48
SPC AC 012110

Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0410 PM CDT Fri Aug 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
Early in the week, a mid-level trough is forecast to remain over the Mississippi Valley, as a ridge builds northward across the High
Plains. To the east of the ridge, moderate to strong instability is
forecast to develop Monday afternoon over parts of the High Plains.
Isolated severe storms that form near the instability axis could
pose a severe threat from the afternoon into the evening, but
limited large-scale ascent should keep any severe threat localized.

On Tuesday, a shortwave mid-level trough is forecast to move through
the northern High Plains. Thunderstorms that form ahead of the
trough in the afternoon could be associated with an isolated severe
threat. The models suggest that this feature will move into northern
Plains Tuesday night into Wednesday. This could result in scattered thunderstorm development early in the day on Wednesday over parts of
the eastern Dakotas. The trough is forecast to exit the region by
Wednesday afternoon. In the wake of the trough, isolated
thunderstorm development could re-develop across the northern Plains
late Wednesday afternoon into the evening. These storms could be
associated with isolated severe gusts and hail.

...Thursday/Day 7 and Friday/Day 8...
On Thursday, a shortwave trough is forecast to move into the
northern Plains. Ahead of the trough, a moist and unstable airmass
should be in place by afternoon. Some model solutions suggest that a
convective cluster will develop Thursday evening over parts of the
eastern Dakotas, with the storms moving east-southeastward into the
upper Mississippi Valley during the overnight period. Considering
that moderate deep-layer shear is forecast, these storms would be
associated with a threat for hail and severe wind gusts. However, predictability at this extended range is low, mainly due to issues
concerning the trough timing and parameter magnitudes.

A severe threat will again be possible on Sunday across parts of the
northern Plains, as a mid-level trough develops and approaches the
region. On Sunday, predictability again is low due to similar
issues.

..Broyles.. 08/01/2025

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ACUS48 KWNS 020902
SWOD48
SPC AC 020900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sat Aug 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
...Tuesday/Day 4 to Thursday/Day 6...
On Tuesday, a mid-level ridge is forecast to remain over the central
Rockies, as a subtle shortwave trough moves into the northern
Plains. Thunderstorm development will be possible near and ahead of
the trough across parts of the Dakotas during the afternoon and
evening. Model forecasts suggest that the environment will support
severe storms, mainly across western and central South Dakota where
an axis of instability and moderate deep-layer shear is forecast.
Isolated large hail and severe gusts are expected to be the primary
threats.

On Wednesday, the shortwave trough is forecast to move eastward into
the upper Mississippi Valley, outrunning the moist and unstable
airmass over the central and northern Plains. Isolated storms could
develop in the wake of the trough over parts of the region, but the
negative effects of a ridge aloft will likely keep any severe threat
localized.

The mid-level ridge is forecast to move eastward into the upper
Mississippi Valley on Thursday, as flow become west-southwesterly in
its wake over the northern Plains. Strong instability could develop
across parts of the region, mainly due to surface dewpoints in the
70s F. Although large-scale ascent is forecast to remain weak in
most areas, a few storms with hail and isolated severe gusts could
develop in the afternoon and evening.

...Friday/Day 7 and Saturday/Day 8...
On Friday, a mid-level shortwave ridge is forecast to move across
the north-central U.S., as a trough moves into the northern Rockies.
Strong instability is forecast to develop by afternoon across much
of the northern Plains and upper Mississippi Valley. Isolated
thunderstorms are expected across parts of the region as surface
temperatures become maximized in the mid to late afternoon. Although
a severe threat will be possible, the presence of the mid-level
ridge could be problematic for a greater severe threat.

On Saturday, a mid-level trough and an associated jet max, is
forecast to move eastward into the northern Plains. Thunderstorm
development will be possible ahead of the trough from the eastern
Dakotas into the upper Mississippi Valley. It appears that the
environment should support a severe threat due strong instability
and substantial deep-layer shear. However, the projected scenario
remains uncertain due to the extended range.

..Broyles.. 08/02/2025

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ACUS48 KWNS 030859
SWOD48
SPC AC 030858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Sun Aug 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
A large-scale mid-level anticyclonic flow pattern will be in place
over much of the central and western U.S during the mid week. At the
surface, a moist and unstable airmass is forecast over the central
and northern Plains. Within the broader scale flow, a shortwave
ridge is forecast to move across the northern Plains from Wednesday
into Thursday. In spite of relatively weak large-scale ascent,
isolated thunderstorm development will be possible on Wednesday and
Thursday as instability becomes maximized in the late afternoon and
early evening. Moderate deep-layer shear should support a potential
for isolated severe gust and hail.

As the mid-level ridge moves eastward during the day on Thursday,
flow is forecast to become southwesterly across the northern High
Plains. Thunderstorms that develop in eastern Montana and western
North Dakota Thursday evening could be associated with a severe
threat. Isolated large hail and severe gusts will be possible. Model
forecasts suggest an isolated severe threat will again be possible
in the northern Plains on Friday, in the wake of the exiting ridge.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday, a mid-level trough is forecast to move into the
northern High Plains, as flow remains southwesterly from the Dakotas
into the upper Mississippi Valley. Model forecasts develop a
relatively large cluster of thunderstorms Saturday evening ahead of
the trough from northwestern Minnesota into eastern South Dakota.
The models also have strong instability and moderate deep-layer
shear in place ahead of the trough within the favored convective
zone. This could support a potential for supercells with large hail
and severe wind gusts. However, the steeper lapse rates are forecast
to remain further south across the mid Missouri Valley, suggesting
there is still some uncertainty concerning the magnitude of the
severe threat.

On Sunday, the severe threat is forecast to shift southeastward as a
front moves across the region. The favored corridor would be along
an axis of moderate instability from northeast Nebraska to
northwestern Wisconsin. This position of the front and instability
axis should be determined by the timing of the mid-level system,
which is still considerably uncertain.

..Broyles.. 08/03/2025

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ACUS48 KWNS 040904
SWOD48
SPC AC 040903

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Mon Aug 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
During the late week time-frame, a mid-level trough is forecast to
develop over the Pacific Northwest and move eastward into the
northern Plains. As the system approaches, a moist and unstable
airmass is forecast across the northern Plains and upper Mississippi
Valley. On Thursday, a lead shortwave trough is forecast to move
across the northern Plains. Large-scale ascent associated with the
trough could result in a cluster of storms with an isolated severe
threat from Thursday evening into the overnight period. Isolated to
scattered thunderstorms may again develop Friday afternoon and
evening, as the exit region of a mid-level jet moves across the
northern Plains. As instability becomes maximized on Friday
afternoon, a severe threat will be possible across parts of the
Dakotas and Minnesota. Large hail and severe gusts will be the
primary threats. The models are in reasonably good agreement on the
timing of the mid-level system. For this reason, have added a 15
percent into the northern Plains to coincide with the projected
locations of the instability axis and mid-level jet.

On Saturday, the mid-level trough is forecast to move into the
northern Plains, as a belt of southwesterly flow shifts eastward
across the Upper Midwest. Thunderstorm development will be possible
in the afternoon and evening, to the east of a front within an
unstable airmass in the upper Mississippi Valley. Moderate
deep-layer shear will again support an isolated severe threat across
the region.

...Sunday/Day 7 and Monday/Day 8...
The front is forecast to move southeastward into the upper
Mississippi Valley on Sunday. This will favor thunderstorm
development along a corridor from Iowa northeastward into Wisconsin,
where an isolated severe threat will be possible in the afternoon
and evening. On Monday, forecasts suggest the instability axis will
remain in a similar location. For this reason, a severe threat could
again affect this same corridor. Due to the extended range in the
forecast, there is some uncertainty concerning this scenario early
next week.

..Broyles.. 08/04/2025

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ACUS48 KWNS 050900
SWOD48
SPC AC 050858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Tue Aug 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
On Friday, a mid-level trough and an associated speed max is
forecast to move into the northern Plains. At the surface, a moist
airmass will be in place over much of the northern Plains, where
surface dewpoints are likely to be in the lower to mid 70s F. As
surface temperatures warm during the day, moderate to strong
instability is expected to develop. Along the northwestern edge of
this unstable airmass, thunderstorms should form in parts of central
and eastern North Dakota. Convective coverage is forecast to expand
southward into South Dakota during the evening. Moderate to strong
deep-layer shear associated with the speed max will be favorable for
a severe threat during the afternoon and evening. Supercells with
large hail, severe wind gusts and a tornado threat will be possible.


On Saturday, the mid-level trough and associated cold front are
forecast to move eastward into the upper Mississippi and mid
Missouri Valleys. Thunderstorms are forecast to be ongoing along and
near the front during the morning, with additional thunderstorm
development taking place further southeast in the afternoon.
Moderate instability and deep-layer shear is forecast across much of
the region, suggesting that a severe threat will again be possible.
There is some uncertainty as to how much the airmass will be
negatively affected by the morning convection. Also, model forecasts
suggest that the greatest convective potential will be during the
overnight period on Saturday. For this reason, will not add a threat
area for Saturday at this time.

On Sunday, a mid-level trough is forecast to move across the
north-central U.S., being positioned from the northern Plains to the
central Rockies by afternoon. A moderately unstable airmass is
forecast further to the east, from the upper Mississippi Valley
southward into the mid Missouri Valley. An isolated severe threat
will be possible Sunday afternoon along and near the instability
axis. However, the mid-level trough is forecast to remain well to
the west of the instability axis, which should limit large-scale
ascent over the unstable airmass, helping to keep any severe threat
isolated.

...Monday/Day 7 and Tuesday/Day 8...
A low-amplitude mid-level trough is forecast to move into the upper
Mississippi Valley on Monday, and into the western Great Lakes on
Tuesday. Further southwest, a mid-level low is forecast across the
central Plains. Thunderstorms will be possible on Monday and Tuesday
afternoon, along the northern edge of a moist airmass from the
central Plains northeastward to the Great Lakes. Model forecasts
suggest that deep-layer shear will be relatively weak. Although
convective coverage and any associated severe threat will likely
remain isolated, a few marginally severe storms could occur in areas
that heat up the most.

..Broyles.. 08/05/2025

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ACUS48 KWNS 060855
SWOD48
SPC AC 060854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Wed Aug 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
...Saturday/Day 4 to Monday/Day 6...
A mid-level trough will move across the northern Plains on Saturday,
as a cold front advances southeastward into the upper Mississippi
and mid Missouri Valleys. Moderate to strong instability should be
in place ahead of the front by afternoon from eastern Nebraska
northeastward into Wisconsin. Thunderstorm development is expected
to take place along parts of the front from the afternoon into the
evening, with the greatest convective coverage over the upper
Mississippi Valley. A few storms could be severe, with large hail
and isolated damaging wind gusts expected to be the primary threats.


On Sunday, another mid-level trough is forecast to move into the
central and northern Plains, as a moist and unstable airmass remains
in place ahead of the front from the mid Missouri Valley
northeastward upper Mississippi Valley. Thunderstorms will again be
possible ahead of the trough near an axis of moderate instability
during the afternoon and evening. Some model forecasts suggest the
strongest instability will not be co-located with the greatest
convective potential. Although a severe threat may develop across
parts of the region, this would negatively affect severe threat
magnitude.

The mid-level trough is forecast to shift eastward across the
north-central U.S. on Monday, as a cold front advances southeastward
across the central Plains and Upper Midwest. Isolated severe
thunderstorms will again be possible ahead of the front near an axis
of moderate instability. However, large-scale ascent will be
somewhat limited across much of the region, suggesting the
convective potential and resulting severe threat should remain
isolated.

...Tuesday/Day 7 and Wednesday/Day 8...
From Tuesday into Wednesday, the mid-level trough and an associated
cold front is forecast to advance eastward from the north-central
U.S. into the Northeast. Along and ahead of the front each afternoon
and evening, strong thunderstorms will be possible. However, the
models are forecasting less instability and a more disorganized
pattern compared to previous days, suggesting that any severe threat
will remain localized.

..Broyles.. 08/06/2025

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ACUS48 KWNS 070845
SWOD48
SPC AC 070843

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0343 AM CDT Thu Aug 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
...Sunday/Day 4 to Tuesday/Day 6...
A persistent shortwave mid-level trough is forecast to remain over
the central U.S. from Sunday to Tuesday. During this time period, a
moist and unstable airmass is forecast to be in place from the
central Plains northeastward into the Great Lakes. It appears that
large-scale ascent will be weak across most of this airmass, which
will result in limited convective coverage. Although instability and
deep-layer shear should be sufficient for an isolated severe threat
each afternoon, mainly in areas that heat up the most, any potential
should remain localized.

Further north into the northern Plains, low-level moisture is
forecast to increase by midweek. In response, a moderately unstable
airmass could develop by Tuesday afternoon. In spite of this, warm
air aloft and limited large-scale ascent should keep convective
coverage very isolated. This will likely limit any related severe
threat.

...Wednesday/Day 7 and Thursday/Day 8...
From Wednesday into Thursday, a mid-level trough is forecast to move
across the northwestern U.S. Ahead of this system, a cold front is
forecast to advance southeastward across the northern Plains.
Thunderstorms would be possible near the front across the Dakotas
Wednesday afternoon, and in the upper Mississippi Valley Thursday
afternoon. An isolated severe threat would be possible for both
days. However, details concerning any potential scenario, including
the timing of the front, is highly uncertain at this time.

..Broyles.. 08/07/2025

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ACUS48 KWNS 080823
SWOD48
SPC AC 080822

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CDT Fri Aug 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
A weak upper trough over the north-central U.S. on Monday/D4 will
move into the upper Great Lakes on Tuesday/D5, then eject into
eastern Canada by Wednesday/D6. From D6 through Friday/D8, another
wave is forecast to develop over the Pacific Northwest, and move
across the northern Rockies.

At the surface, a moist air mass will remain over much of the
central and eastern states, with minimal surface focus. However,
daily areas of thunderstorms, some with gusty winds, are likely to
occur from the upper Great Lakes to the southern Plains for
Monday/D4 into Tuesday/D5, and then into the OH/TN Valleys and
Northeast thereafter.

Perhaps by D7/D8, the northern Rockies trough will interact with
stronger instability over the northern Plains with a wind or hail
threat, but predictability is low this far out for such a minimal
system.

..Jewell.. 08/08/2025

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ACUS48 KWNS 090819
SWOD48
SPC AC 090817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Sat Aug 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
A shortwave trough will move from the northern Plains into the
Northeast during the Tuesday/D4 to Wednesday/D5 time frame, with an
initial push of drier air southward across the Midwest/Great Lakes.
Stronger instability is forecast to redevelop by Thursday/D6 and
beyond as a low-amplitude upper trough moves across the northern
Rockies and Plains and increasing southerly low-level winds bring
dewpoints into the mid 70s F northward across the Mid MO/Upper MS
Valleys. This may yield one or more severe events across parts of
the northern Plains to upper MS Valley, but confidence is low.

..Jewell.. 08/09/2025

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ACUS48 KWNS 100825
SWOD48
SPC AC 100824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Sun Aug 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
From Wednesday/D4 into Thursday/D5, a shortwave trough is forecast
to move from the Pacific Northwest across MT and over the far
northern Plains, with an upper speed max developing into southern SK
and MB. In advance of this trough, a leading trough affecting the
Great Lakes region will also lift northeastward, with height rises
and a warming pattern across parts of the Plains and upper Midwest.
The combination of increasing dewpoints and the upper trough
glancing the region may result in some manner of severe risk late
Thursday/D5, and most likely from parts of ND into northern MN, and
in evening/overnight MCS form. Future model trends will be monitored
for a possible risk area.

From Friday/D6 onward, predictability decreases with the motion of
the aforementioned upper wave. However, large instability is likely
to again build across the Mid MO/Upper MS Valleys, and at least
sporadic severe storms cannot be ruled out from the northern High
Plains eastward toward the Upper Great Lakes.

..Jewell.. 08/10/2025

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ACUS48 KWNS 110853
SWOD48
SPC AC 110852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Mon Aug 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
On Thursday/D4, a shortwave trough is forecast to move from MT into
the northern Plains, with primary upper low well to the north. A
surface trough and cold front should push eastward across the
Dakotas as well, and extend roughly from MN into NE by Friday/D5
morning. Model spread is high regarding the amount of moisture
return and instability, with some models likely over-estimating real instability. In any case, storms appear most likely from ND into
northern MN, beneath 50+ kt midlevel westerlies. As such, a 15%
severe area has been introduced.

This wave will progress east/northeastward on Friday/D5, with a
front trailing southwestward perhaps from Lake Superior across WI/MN
and toward NE. A moist and unstable air mass will remain near and
south of any such boundary, but the position of said boundary may
depend on storms from the previous night, or possibly a continuation
of such storms. Predictability is therefore low on Friday/D5.

Beyond this time frame, it appears the storm track will shift
northward into Canada, with upper ridging over much of the CONUS.

..Jewell.. 08/11/2025

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ACUS48 KWNS 120812
SWOD48
SPC AC 120811

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0311 AM CDT Tue Aug 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
From Friday/D4 into Saturday/D5, an upper low will move from
Manitoba across Hudson Bay and into Quebec. Moderate midlevel
westerlies will exist over the far northern Plains to Upper Great
Lakes during this period, with gradual weakening. An upper high will
also be centered over the mid MS Valley, while a weak midlevel
trough with cool air aloft slowly departs the Great Basin.

At the surface, a front is forecast to stall on Friday/D4 from
northern NE across southern MN and into northern WI, with a moist
and unstable air mass remaining to the south. This front will remain
over roughly the same zone into Saturday/D5, and perhaps as late as
Sunday/D6.

Given that the moist and unstable air mass will persist over parts
of the northern Plains/Upper MS Valley, and minor ripples in the
flow are hinted at by several models, areas of storms are expected.
However, storm/MCS corridors are difficult to pinpoint this far out.
In general, the area from SD into WI will bear watching for wind
potential.

From Sunday/D6 onward, an upper ridge is expected to build over much
of the western and central states, with a reduction in severe
potential overall.

..Jewell.. 08/12/2025

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ACUS48 KWNS 130846
SWOD48
SPC AC 130844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Wed Aug 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
During the Saturday/D4 to Sunday/D5 time frame, a weak midlevel wave
may affect the far northern Plains to upper Great Lakes, rounding
the building upper ridge. Meanwhile, a boundary will exist roughly
from ND/MN into MI, with latitudinal uncertainty. A moist air mass
will remain across this zone, with periodic storm complexes
possible. Predictability is low but at least some wind risk may
develop across portions of this zone.

For the rest of the period through at least Wednesday/D8, a large
upper ridge is forecast to build over much of the West/Rockies, with
minimal severe risk.

..Jewell.. 08/13/2025

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ACUS48 KWNS 140828
SWOD48
SPC AC 140826

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0326 AM CDT Thu Aug 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
An upper ridge is forecast to build over the Plains and Rockies
through Tuesday/D6, with the upper high retrograding from the
central Plains to the Four Corners. East of the ridge axis,
northwest midlevel flow of 20-30 kt will persist over the upper MS
Valley/Great Lakes, with a large area of moisture and instability
roughly from MN/IA to IL/IN. This pattern should support corridors
of thunderstorms in the low-level warm advection zone, or along the
northern instability gradient through Tuesday/D6. While areas of
strong wind gusts will be possible, the overall severe probably is
less than the 15% threshold over this large zone.

The upper ridge may flatten over the northern Rockies/Plains beyond
D6, with perhaps an eventual northwest flow regime coinciding with
residual instability, supporting at least minimal severe potential
over the northern Plains.

..Jewell.. 08/14/2025

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ACUS48 KWNS 150845
SWOD48
SPC AC 150844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Fri Aug 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
At mid-levels, heights are forecast to rise across the north-central
states on Monday and Tuesday, as west-northwesterly flow remains
from parts of the northern Plains to the Eastern Seaboard.
Thunderstorm development will be possible each day along parts of a
front, which is forecast to be slow-moving and situated from the
northern Plains east-southeastward into the southern Great Lakes. An
isolated severe threat will be possible in the vicinity of the front
within a moderately unstable airmass on Monday from parts of South
Dakota eastward into the western Great Lakes. Storms with an
isolated severe threat will again be possible on Tuesday. The
greatest convective coverage is forecast to be further to the east
from the southern Great Lakes into the central Appalachians.

On Wednesday, isolated to scattered thunderstorms are expected over
parts of the mid Mississippi and lower Ohio Valleys. In this area,
large-scale ascent and deep-layer shear are forecast to be weak
suggesting the potential for severe storms will remain low.

...Thursday/Day 7 and Friday/Day 8...
On Thursday, a cold front is forecast to move into the northern
Plains. Thunderstorm development will be possible ahead of the front
along an axis of instability from parts of South Dakota into
northwestern Minnesota. An isolated severe threat may develop with
this activity during the afternoon and evening. The potential for
isolated severe is forecast to shift southeastward into the mid
Missouri upper Mississippi Valleys on Friday. However, uncertainty
is low at this range in the forecast period.

..Broyles.. 08/15/2025

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ACUS48 KWNS 160857
SWOD48
SPC AC 160856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Sat Aug 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
A mid-level ridge will build across the Rockies and northern High
Plains during the middle part of the week. At the surface, a front
will advance slowly southward into the lower Missouri and mid
Mississippi Valleys. A post-frontal airmass will remain over the
upper Mississippi and Great Lakes region. On the southern and
western periphery of this airmass, moderate instability is forecast
to develop each afternoon. Limited large-scale ascent is expected to
keep convective coverage isolated. In spite of relatively weak
deep-layer shear along much of the instability corridor, steep low
to mid-level lapse rates will be in place and could be enough for a
marginal severe threat in areas that destabilize the most.

...Thursday/Day 6 and Saturday/Day 8...
Mid-level zonal flow is forecast to develop on Thursday over much of
the north-central and northwestern U.S., as a ridge moves
southeastward into the western Great Lakes. A pocket of moderate
instability is forecast to develop ahead of a cold front on Thursday
in the northern Plains. Limited large-scale ascent should keep
convective coverage isolated. Although deep-layer shear is forecast
to be modest, any cell that can develop and persist near the
stronger instability in the late afternoon and early evening could
obtain an isolated severe threat.

On Friday an Saturday, a cold front is forecast to move
southeastward across the north-central U.S. Near and ahead of the
front, isolated thunderstorms will be possible each afternoon from
the upper Mississippi Valley into the Great Lakes region. The
combination of instability and shear could be sufficient for an
isolated severe threat. However, considerable uncertainty exists at
this range in the forecast.

..Broyles.. 08/16/2025

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ACUS48 KWNS 170855
SWOD48
SPC AC 170854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sun Aug 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
On Wednesday, a mid-level ridge will likely be in place across the
northern Plains. At the surface, a front is forecast to be located
over the Ozarks and lower Ohio Valley. Moderate instability is
expected to develop to the south of the front, and over parts of the north-central states. In areas where storms are expected, deep-layer
shear should be weak, suggesting a severe threat is unlikely.

On Thursday, a mid-level shortwave trough and an associated cold
front are forecast to move eastward into the northern Plains. An
axis of moderate instability is forecast ahead of the front. This
combined with moderate deep-layer shear could be enough for an
isolated severe threat during the afternoon and evening, mainly over
eastern North Dakota and northwestern Minnesota.

The front and its associated shortwave trough are forecast to move
into the upper Mississippi and mid Missouri Valleys on Friday.
Moderate instability appears likely to develop ahead of the front
during the afternoon. Along and near the instability axis, the
greatest potential for thunderstorm development could occur in the
central Plains within northwest mid-level flow. An isolated severe
threat will be possible during the late afternoon and early evening.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday and Sunday, an upper-level trough is forecast to remain
over the Great Lakes region. Ahead of the trough, an axis of
instability is forecast to develop in the central Appalachians,
where isolated to scattered thunderstorms will be possible each
afternoon. Moderate deep-layer shear could be sufficient for an
isolated wind-damage threat, mainly in the late afternoon as
low-level lapse rates become steep.

..Broyles.. 08/17/2025

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ACUS48 KWNS 180854
SWOD48
SPC AC 180852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Mon Aug 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
On Thursday, a subtle shortwave trough is forecast to move eastward
across the northern Plains. An axis of moderate instability will
likely develop by afternoon ahead of the front across the eastern
Dakotas and northwest Minnesota. Scattered storms could develop
during the afternoon near the instability axis, with an isolated
severe threat possible.

On Friday, the front is forecast to move southeastward toward the
upper Mississippi and mid Missouri Valleys, as an axis of
instability develops during the afternoon. Isolated thunderstorms
will be possible near the instability axis, but the severe potential
is expected to remain localized, mostly due to minimal convective
coverage.

On Saturday, the front is forecast to move across the Great Lakes
region, extending west-southwestward into the central U.S. Isolated
storms with a potential for localized severe will again be possible
in the afternoon ahead of the front. Due to a lack of large-scale
ascent, cell coverage is expected to be very isolated.

...Sunday/Day 7 and Monday/Day 8...
From Sunday into Monday, an upper-level trough and an associated
cold front is forecast to move across the eastern U.S. Thunderstorm
development will be possible ahead of the front Sunday afternoon in
the central Appalachians, and along parts of the middle to upper
Atlantic Seaboard on Monday afternoon. Instability ahead of the
front is expected to remain weak in most areas during this period,
suggesting any severe threat will remain localized.

..Broyles.. 08/18/2025

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ACUS48 KWNS 190850
SWOD48
SPC AC 190849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Tue Aug 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
...Friday/Day 4 to Sunday/Day 6...
On Friday, a mid-level shortwave trough and an associated cold front
is forecast to move into the upper Mississippi Valley. An axis of
moderate instability will likely develop by afternoon ahead of the
front from the western Great Lakes southwestward into the mid
Missouri Valley. Due to limited large-scale ascent, convective
coverage near the instability axis is expected to be very isolated.
A marginal risk will be possible with cells that develop close
enough to the instability axis.

On Saturday, the front is forecast to move through the Great Lakes
region, extending southward into the central Plains. Instability
will again develop ahead of the front, but convective initiation
should remain isolated due to a lack of large-scale ascent. The area
with the greatest potential for a marginal severe threat would be
over the central Great Lakes ahead of a shortwave trough.

The shortwave trough is forecast to amplify over the Great Lakes
region on Sunday, as the cold front advances through the lower Great
Lakes and Ohio Valley. Instability will increase during the day
ahead of the front over the central Appalachians with scattered
thunderstorms developing during the afternoon. Deep-layer shear
should be strong enough for an isolated wind-damage threat, mainly
in areas where instability is stronger.

...Monday/Day 7 and Tuesday/Day 8...
A cold front is forecast to advance towards the Eastern Seaboard on
Monday. Scattered thunderstorms will be possible Monday afternoon
ahead of the front from New England southward into the Mid-Atlantic.
Although moderate deep-layer shear is forecast, instability should
remain weak, suggesting any severe threat will be marginal. Although uncertainty is substantial at this extended range, the models keep a
relatively dry post-frontal airmass over much of the central and
eastern U.S on Tuesday. Along the southern periphery of this
airmass, isolated thunderstorms will be possible in the southern
Plains and Ark-La-Tex Tuesday afternoon. However, weak instability
is expected to limit severe threat potential.

..Broyles.. 08/19/2025

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ACUS48 KWNS 200804
SWOD48
SPC AC 200803

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0303 AM CDT Wed Aug 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
...D4/Saturday - D6/Monday...
On D4/Saturday, a seasonably strong cold front will move across
parts of the south-central Great Plains into the mid MS Valley and
southern Great Lakes region, as a deep mid/upper-level trough
becomes established over much of the central/eastern CONUS. Somewhat
favorable deep-layer flow/shear could support strong to locally
severe storms along the front, though generally modest instability
may tend to limit the magnitude of the severe threat. Strong storms
may also develop within a post-frontal regime across parts of the
central High Plains.

The cold front will make further south/east progress on D5/Sunday,
and locally strong storms may develop from parts of the Northeast
into the central/southern Appalachians. Generally weak instability
may tend to limit coverage of the organized severe threat. Strong
storms may also develop again within a post-frontal regime across
parts of the central/southern High Plains.

The cold front may tend to slow down by D6/Monday across parts of
the Mid Atlantic and Northeast, though guidance begins to diverge
regarding the evolution of the deep upper trough and potential for
surface low development off of the Mid Atlantic coast. Some
potential for strong storms could again evolve along the front, from
parts of New England into the Mid Atlantic.

...D7/Tuesday - D8/Wednesday...
While predictability continues to wane regarding the details,
extended-range guidance generally depicts persistence of the eastern
CONUS upper trough into the middle of next week, though it may begin
to shift eastward with time. In the wake of the cold frontal
passage, an expansive surface ridge is forecast to maintain
generally stable conditions for most areas east of the Rockies,
resulting in limited potential for organized severe storms.

..Dean.. 08/20/2025

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ACUS48 KWNS 210811
SWOD48
SPC AC 210809

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0309 AM CDT Thu Aug 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
...D4/Sunday - D5/Monday...
A cold front that moves into the eastern CONUS on Sunday may tend to
slow down, as a reinforcing shortwave moves through the base of a
deep mid/upper-level trough covering the region. Scattered storms
will be possible from the Northeast into the central/southern
Appalachians on D4/Sunday, though with only modest instability and
deep-layer shear forecast to be in place, any severe potential may
remain isolated. Stronger deep-layer flow/shear is generally
forecast to overspread parts of the Northeast/New England on
D5/Monday, though with generally weak instability expected, severe
potential is uncertain.

Scattered storms will also be possible on Sunday and Monday across
the CO Front Range vicinity into the central High Plains, within a
persistent post-frontal regime. While details are uncertain, strong
to isolated severe storms cannot be ruled out, especially if any
organized clustering can develop and emerge into parts of the High
Plains.

...D6/Tuesday - D8/Thursday...
While typical model spread is noted by Days 6-8, guidance generally
depicts relatively limited severe potential into the middle of next
week, as an expansive surface ridge suppresses richer low-level
moisture to parts of the Gulf Coast and Texas. Some guidance shows
potential for recovery by D8/Thursday across parts of the
southern/central Plains, but deep-layer flow is generally forecast
to remain weak to modest across the region.

..Dean.. 08/21/2025

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ACUS48 KWNS 220848
SWOD48
SPC AC 220846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Fri Aug 22 2025

Valid 251200Z - 301200Z

...DISCUSSION...
...Monday/Day 4 to Wednesday/Day 6...
On Monday, a cyclonic-flow mid-level pattern will be in place across
much of the eastern two-thirds of the nation. Southwesterly flow is
expected over the Northeast, where scattered thunderstorms will be
possible on Monday, mainly in New England. Scattered storms are also
expected to develop in parts of the southern and central Plains
within northwesterly flow. Any severe threat in these two areas will
likely remain localized, mainly due to weak instability.

On Tuesday and Wednesday, a large area of high pressure is forecast
to be in place from the central and northern Plains eastward to the
Atlantic Seaboard. Thunderstorms, non severe in nature, would be
possible each afternoon across parts of the Gulf Coast states and in
the southern and central High Plains, along the southern and western
periphery of the post-frontal airmass.

...Thursday/Day 7 and Friday/Day 8...
From Thursday into Friday, a mid-level low is forecast to form over
the lower Great Lakes, as a large area of surface high pressure
moves slowly eastward across the eastern U.S. Scattered
thunderstorms could form in parts of the southern Plains and High
Plains, but weak instability should limit any severe potential.

..Broyles.. 08/22/2025

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ACUS48 KWNS 230838
SWOD48
SPC AC 230836

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0336 AM CDT Sat Aug 23 2025

Valid 261200Z - 311200Z

...DISCUSSION...
...Tuesday/Day 4 to Thursday/Day 6...
A large-scale trough will remain in place across the eastern U.S. on
Tuesday, as an area of surface high pressure remains dominant across
much of the eastern half of the nation. Non-severe thunderstorms may
develop on the western periphery of post-frontal airmass, over parts
of the southern and central High Plains on Tuesday and Wednesday.

On Thursday, low-level moisture return is forecast to take place
across the southern and central Plains. A pocket of moderate
instability will be possible across parts of Oklahoma, where
scattered thunderstorms may develop during the afternoon. In spite
of this, deep-layer shear is forecast to remain relatively weak,
suggesting any severe threat will be marginal.

...Friday/Day 7 and Saturday/Day 8...
From Friday into Saturday, northwesterly mid-level flow will remain
in place over parts of much of the central and eastern part of the
nation. At the surface, a moist airmass will likely be located over
parts of the Gulf Coast states, where scattered thunderstorms will
be possible each day. Deep-layer shear is forecast be relatively
weak across most of the region from Friday into Saturday, suggesting
that any severe threat will remain localized.

..Broyles.. 08/23/2025

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ACUS48 KWNS 240840
SWOD48
SPC AC 240838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Sun Aug 24 2025

Valid 271200Z - 011200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
On Wednesday, a large-scale cyclonic flow pattern is forecast to
remain over the north-central and northeastern U.S., as a mid-level
ridge remains over the southern and central Rockies. Low-level
moisture return is forecast over the southern and central Plains,
where an axis of instability should set up from west Texas into
eastern Colorado by afternoon. Scattered thunderstorms may develop
from near the instability axis eastward across Kansas from late
afternoon into the evening. Weak instability should keep any severe
potential localized.

On Thursday, an axis of moderate instability is forecast to develop
by afternoon across east Texas and eastern Oklahoma. As a mid-level
shortwave trough moves southeastward across the region, isolated
scattered thunderstorms will be possible over much eastern Oklahoma
extending eastward into the Ozarks. Instability and deep-layer shear
should be enough for a marginal severe threat in these areas. This
potential is forecast to shift southward into southeast Texas on
Friday, as a cold front advances toward the Gulf Coast.

...Saturday/Day 7 and Sunday/Day 8...
On Saturday and Sunday, a mid-level ridge is forecast over the
western U.S., as northwesterly flow remains over much of the central
and eastern U.S. An axis of instability may develop over parts of
the southern and central High Plains each afternoon, where isolated thunderstorms will be possible. Any severe threat associated with
the storms is expected to be localized.

..Broyles.. 08/24/2025

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ACUS48 KWNS 250854
SWOD48
SPC AC 250853

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0353 AM CDT Mon Aug 25 2025

Valid 281200Z - 021200Z

...DISCUSSION...
...Thursday/Day 4 to Saturday/Day 6...
On Thursday, a large-scale mid-level trough is forecast to be in
place over the eastern U.S., as a ridge remains over the central
Rockies. A pocket of moderate instability could develop in the
Ark-La-Tex Thursday afternoon, near an east-to-west front in the Red
River Valley. Enough deep-layer is forecast for an isolated severe
threat, but some uncertainty exists concerning the magnitude of any
threat.

The front is forecast to move southward into the Gulf Coast states
on Friday. Thunderstorm development will be possible near the front
from east Texas into Louisiana, where an isolated severe threat
could again develop during the afternoon. However, deep-layer shear
is forecast to remain relatively weak, would should keep any severe
threat marginal.

Further northwest on Friday, an axis of instability is forecast
across the southern and central High Plains. Isolated to scattered thunderstorms could develop along and near this axis from late
afternoon into the evening. This same potential will be possible on
Saturday as the instability axis remains in place across the
southern and central High Plains. The combination of instability and
deep-layer shear is forecast to be sufficient for a marginal severe
threat both on Friday and Saturday.

...Sunday/Day 7 and Monday/Day 8...
From Sunday into Monday, a mid-level ridge is forecast to move
eastward across the southern and central Plains. In the wake of this
feature, scattered thunderstorms could develop across the High
Plains near a north-to-south axis of instability. A marginal severe
threat will be possible each afternoon and evening, but deep-layer
shear is forecast remain relatively weak. This should be a limiting
factor concerning any severe potential.

..Broyles.. 08/25/2025

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ACUS48 KWNS 260749
SWOD48
SPC AC 260747

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 AM CDT Tue Aug 26 2025

Valid 291200Z - 031200Z

...DISCUSSION...
An upper trough will eject into the Atlantic this weekend as weak
upper ridging builds into the central U.S. and an upper-low meanders
over the Pacific Northwest. An upper trough will then develop and
gradually amplify over the Upper MS Valley through early next week.
A surface cold front will sag southward through the day on Day
4/Friday across portions of the southern Plains into the Lower MS
Valley, where rich moisture and appreciable instability will be in
place to support a threat for at least scattered strong
thunderstorms. By the weekend into early next week, surface lee
troughing across the Plains will encourage the northwestward
advection of low-level moisture beneath modest lapse rates,
resulting in marginal to moderate instability across the High Plains
Days 5-8/Saturday-Tuesday. Southeasterly 850 mb winds, overspread by northwesterly flow at 500 mb, may encourage enough wind shear to
support isolated severe storms along the central High Plains
Saturday-Tuesday.

..Squitieri.. 08/26/2025

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ACUS48 KWNS 270752
SWOD48
SPC AC 270751

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0251 AM CDT Wed Aug 27 2025

Valid 301200Z - 041200Z

...DISCUSSION...
The upper-low over New England will gradually drift away from the
U.S. as an upper ridge builds west of the Rockies this weekend into
early next week. Surface troughing will persist across the Plains
states, with adequate low-level moisture remaining in place to
support scattered thunderstorms. At the moment, it appears that any
severe risk will be sparse at best. As the upper ridge persists, a
positively tilted upper trough will rapidly translate from Canada
into the MS Valley during the middle of next week, accompanied by a
progressive surface cold front. This cold front will bring a cool,
stable airmass to much of the northern and central Plains into the
MS Valley, reducing thunderstorm potential. Strong storms could
occur immediately ahead of the surface cold front around Day
8/Wednesday, though questions surrounding the placement and timing
of this front preclude the introduction of severe probabilities at
this time.

..Squitieri.. 08/27/2025

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ACUS48 KWNS 280751
SWOD48
SPC AC 280750

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0250 AM CDT Thu Aug 28 2025

Valid 311200Z - 051200Z

...DISCUSSION...
Upper troughs will impinge on the West and East Coasts while upper
ridging dominates the Interior West early next week, before a
mid-level trough develops and rapidly amplifies across the eastern
half of the CONUS through the middle of next week. Through the early
part of the week, surface lee troughing, amid weaker deep-layer flow
fields, will support meandering moisture across the central U.S.,
accompanied by thunderstorm chances. As the aforementioned mid-level
trough amplifies, a strong surface cold front will sweep across the
Plains and MS Valley region during the middle of the week, promoting
cool and stable conditions. Given the strength of the cold front, it
is plausible that thunderstorm development should occur given strong
low-level convergence. However, medium-range guidance does not
depict a strong signal of overlapping buoyancy and vertical wind
shear ahead of the cold front, suggesting that if severe potential
exists, the predictability of this potential is too low to warrant probabilities at this time.

..Squitieri.. 08/28/2025

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ACUS48 KWNS 290834
SWOD48
SPC AC 290833

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0333 AM CDT Fri Aug 29 2025

Valid 011200Z - 061200Z

...DISCUSSION...
A broad northwesterly upper flow regime will be in place across the
CONUS early this week, before a pronounced mid-level trough
amplifies greatly while tracking across the eastern CONUS through
the remainder of the week. As this occurs, surface low development
is likely around the Great Lakes, with a strong cold front poised to
sweep across the northern Plains to the East Coast during the Days
5-8 (Tuesday-Friday) time frame. Cool and stable conditions will
usher in behind the cold front. However, Gulf moisture may advect north-northeast ahead of the front along the East Coast toward the
end of the week. Assuming forcing for ascent is not purely
anafrontal, it is plausible that at least isolated severe storms
could develop along the East Coast around Days 7-8
(Thursday-Friday). However, confidence in the specific timing and
magnitude of any severe threat this far in advance is too low for
the introduction of severe probabilities at this time.

..Squitieri.. 08/29/2025

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ACUS48 KWNS 300846
SWOD48
SPC AC 300844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Sat Aug 30 2025

Valid 021200Z - 071200Z

...DISCUSSION...
A mid-level trough is poised to rapidly amplify while traversing the
eastern U.S. from around mid-week into next weekend, encouraging a
surface cold front to sweep across the northern Plains to the East
Coast Days 4-7 (Tuesday-Friday). Around Day 6 (Thursday), the
surface cold front should encounter richer low-level moisture while
impinging on the Appalachians. Surface dewpoints well into the 60s F
may support MUCAPE around 1000 J/kg. However, much of the stronger
vertical wind shear and associated upper support may potentially lag
the surface cold front. As such, uncertainties remain regarding
severe potential, with no probabilities introduced this outlook.
Nonetheless, it is plausible that a broken band or line of storms
with at least scattered gusty conditions (perhaps damaging winds)
may organize to the immediate lee of the Appalachians on Thursday.
By the weekend, medium-range guidance hints at the possibility of
moisture return to the southern Plains, along with instability,
which may foster isolated severe potential.

..Squitieri.. 08/30/2025

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ACUS48 KWNS 310851
SWOD48
SPC AC 310849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Sun Aug 31 2025

Valid 031200Z - 081200Z

...DISCUSSION...
A surface cold front will surge east-southeastward across the Plains
states and the MS Valley Day 4 (Wednesday) before impinging on the
East Coast by Days 5-6 (Thursday-Friday) as a mid-level trough
amplifies over the Great Lakes. Adequate low-level moisture will
precede the cold front, supporting potentially strong thunderstorms
over the southern Plains on Wednesday given favorable overlapping shear/instability. Thereafter, potentially strong thunderstorms may
develop ahead of the cold front over the central/northern
Appalachians into the Hudson River Valley Thursday and Friday as the
cold front encounters progressively richer moisture. The main
limiting factor for a clearer severe threat is the potential for
deep-layer ascent/shear potentially lagging behind the cold front.
Nonetheless, convergence along the surface cold front may still
support enough of a severe threat to warrant probabilities by the
Days 1-3 time frame. Medium-range guidance depicts some moisture
return across the southern Plains by the end of the week into next
weekend, as a second mid-level impulse pivots around the broader
cyclonic flow enveloping the eastern U.S. Should this occur, enough
favorable overlapping buoyancy and shear may support an isolated
severe risk.

..Squitieri.. 08/31/2025

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ACUS48 KWNS 010817
SWOD48
SPC AC 010816

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Mon Sep 01 2025

Valid 041200Z - 091200Z

...DISCUSSION...
A pronounced mid-level trough will gradually advance eastward across
the eastern U.S. through the remainder of the week into this
weekend, with multiple embedded mid-level perturbations expected to
pivot around the upper trough. The upper trough and associated
impulses will reinforce surface high pressure and cooler air across
much of the U.S. between the Mississippi River and Appalachians
through the extended forecast period. The surface cold front will
encounter seasonably rich low-level moisture while encroaching on
the Eastern Seaboard, prompting the development of at least
scattered thunderstorms. At the moment, the best chance for strong
storms, perhaps accompanied by an isolated severe threat, will be
along the central and northern Appalachians into the Mid Atlantic
within the Days 4-6 (Thursday-Saturday) time frame.

Meanwhile, as surface high pressure builds over the OH/TN Valley
regions, and the Interior West, seasonal moisture return is expected
across parts of the southern Plains due to surface lee troughing.
The aforementioned impulses pivoting around the broader scale upper
trough may graze the southern Plains, perhaps promoting enough
vertical wind shear atop a moist low-level airmass to support
isolated severe thunderstorms Days 4-6 (Thursday-Saturday).

..Squitieri.. 09/01/2025

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ACUS48 KWNS 020835
SWOD48
SPC AC 020834

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0334 AM CDT Tue Sep 02 2025

Valid 051200Z - 101200Z

...DISCUSSION...
A pronounced mid-level trough will progress across the Northeast
late this week, ejecting into the Atlantic by the end of the
weekend. Thereafter, a more progressive pattern will ensue, with
multiple mid-level shortwave troughs poised to traverse the CONUS
early into the middle of next week. Despite differences among
medium-range guidance members, there is general agreement that a
surface cold front will encounter seasonal low-level moisture across
the eastern U.S. Days 4-5 (Friday-Saturday), promoting thunderstorm
potential (some of which may be strong). However, any severe threat accompanying these storms is expected to be localized and isolated.
Surface high pressure will then become established from the MS River
Valley eastward, allowing for moisture return across the Plains
states by next week. Nonetheless, overall forcing for ascent, along
with buoyancy, are expected to be weak over the Plains next week,
with severe potential currently appearing low.

..Squitieri.. 09/02/2025

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ACUS48 KWNS 030818
SWOD48
SPC AC 030817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Wed Sep 03 2025

Valid 061200Z - 111200Z

...DISCUSSION...
The western North American midlevel ridge of the previous days will
slowly move east into the central continent by the end of the
forecast period and in its place an amplified longwave trough will
take hold across the western US.

... Saturday/Day-4 ...
Before this transition happens, a seasonably strong cold front will
push east into the Atlantic and south into the northern Gulf states
as an expansive surface high will move into the central US on
Saturday/Day-4. Guidance disagrees to the degree instability will
materialize along and ahead of the front from the Mid-Atlantic
region into New England. However, pattern recognition would support
scattered strong thunderstorms along the front across this region.
Midlevel flow will be sufficiently strong to support at least some
damaging wind potential should thunderstorms develop.

... Sunday/Day-5 through Wednesday/Day-8 ...

A seasonably cool, dry continental airmass will be in place across
much of the eastern two-thirds of the contiguous US, resulting in
low potential of organized severe thunderstorms on Sunday/Day-5.
That said, as the western trough takes hold, lee troughing will
develop across the High Plains. This will result in return flow
drawing low-level northward by early next week. Weak shortwave troughs/vorticity maxima embedded in the increasingly southwesterly
flow may yield thunderstorms across the High Plains during the late
afternoon into the overnight hours. Depending on the quality of the
resulting low-level moisture return and the strength of any of these
shortwave troughs, the potential for organized severe thunderstorms
may develop, especially later in the forecast period. However,
predictability of these features at this time scale is too low to
warrant unconditional probabilities at this time.

..Marsh.. 09/03/2025

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ACUS48 KWNS 040848
SWOD48
SPC AC 040846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Thu Sep 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
A seasonally cool and dry continental airmass will be in place
across much of the eastern US at the start of the forecast period,
resulting in low severe potential. By Monday/Day-5, the surface high
pressure responsible for this airmass will have begun to move east
allowing return flow to become established across the Plains. At the
same time, lee troughing in response to a western US longwave trough
will reinforce the return flow regime.

As the moisture is drawn northward into the Plains, steep lapse
rates will advect out into the Plains from the higher elevations to
the west. This combination of moistening low-levels and steep
midlevel lapse rates will support increasing buoyancy profiles
through the week.

Any subtle shortwave trough that ejects out of the western trough
and emerges into the central and northern Plains will have an
opportunity to tap into this moist, buoyant atmosphere. The result
would be at least some potential for thunderstorms, some of which
could be severe. However predictability of these kinds of subtle
features is too poor at these lead times to attempt to highlight
favored days or corridors, thus predictability remains too low for unconditional probabilities.

..Marsh.. 09/04/2025

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ACUS48 KWNS 050855
SWOD48
SPC AC 050854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Sep 05 2025

Valid 081200Z - 131200Z

...DISCUSSION...
Upper-level ridging within the West will slowly shift into the
Plains this weekend and into perhaps the middle of next week. Modest
to moderate mid-level flow will generally continue across the Midwest/Northeast. In the West, current guidance shows a trough
slowly making progress east next week. Model guidance has shown a
high degree of variability with regard to how this western trough
will evolve through time. Expansive surface high pressure will be
present in parts of the Plains and points eastward. With time, this
high will move east and promote southerly return flow across the
Plains. This process will accelerate as the western trough
approaches. While some strong to severe storms will be possible as
moisture returns northward, the timing and location of this
potential largely depends on where surface boundaries set up and
where smaller scale perturbations will eject into the Plains. The predictability of these features remains low at this time.

..Wendt.. 09/05/2025

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ACUS48 KWNS 060900
SWOD48
SPC AC 060859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat Sep 06 2025

Valid 091200Z - 141200Z

...DISCUSSION...
Medium range guidance shows good agreement on the upper-level
pattern from next Tuesday into late next week. A western trough will
remain within the Great Basin and Northwest while a ridge across the
Plains will make very slow eastward progress. The overall pattern
will favor at least a narrow zone of moisture return northward into
parts of the Plains. Where models differ is when stronger mid-level
winds will spread into the Plains. The GFS suggests this could
happen late this coming week while the ECMWF shows the trough
ejecting more towards next weekend. Even with these differences,
some severe risk could develop within the High Plains/Plains near
surface boundaries or where small scale perturbations provide
additional ascent. Give the low predictability of these key
features, severe probabilities will continue to be withheld.

..Wendt.. 09/06/2025

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ACUS48 KWNS 070900
SWOD48
SPC AC 070858

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Sun Sep 07 2025

Valid 101200Z - 151200Z

...DISCUSSION...
The mid-level flow pattern across the US is forecast to become more
stagnant into the extended-range forecast period as the western US
upper low deepens and shortwave ridging over the Plains moves slowly
eastward. Broad troughing over the East should gradually
consolidate, slowing eastward progress of the upper ridge. As the
western trough slowly approaches the Rockies, a lee trough should
sharpen each afternoon with a narrow zone of moisture return along
and east into parts of the High Plains. Sufficient destabilization
is expected to support isolated thunderstorms, and perhaps some
severe risk, near the lee trough as smaller embedded perturbations
eject eastward periodically. However, with only slow movement of the
upper ridge expected, forcing for ascent should remain modest until
early next weekend. Somewhat greater severe potential may develop
D6/Friday or D7/Saturday as the primary upper trough begins to
emerge over the Plains. However, given the uncertainties associated
with the smaller scale features, and the timing of the main trough,
limited confidence exists regarding severe potential in the extended
forecast.

..Lyons.. 09/07/2025

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ACUS48 KWNS 080902
SWOD48
SPC AC 080900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Mon Sep 08 2025

Valid 111200Z - 161200Z

...DISCUSSION...
The primary focus for isolated severe potential for the next several
days will be the upper low over the western US. The upper low is
forecast to slowly deepen late this week as it drifts eastward.
Shortwave ridging over the Plains is also forecast to move eastward,
gradually breaking down into this weekend. Surface high pressure
over the eastern US will allow modest return flow into the western
Plains along a lee trough and weak surface low over the Dakotas.
Sufficient destabilization is expected to support isolated
thunderstorms, and perhaps some severe risk, near the surface trough
as several shortwave perturbations within the southwesterly flow
ahead of the primary upper low move over the Plains. Somewhat
greater severe potential may develop this weekend as the upper low
ejects over the Plains and more robust moisture. However,the upper
trough may begin to weaken with the stronger flow aloft being
displaced north of the best moisture and buoyancy. While isolated
severe potential may exist each afternoon over the central and
northern Plains into early next week, confidence in widespread
severe potential remains too low for probabilities at this time.

..Lyons.. 09/08/2025

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ACUS48 KWNS 090901
SWOD48
SPC AC 090859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Tue Sep 09 2025

Valid 121200Z - 171200Z

...DISCUSSION...
As shortwave ridging begins to breakdown into this weekend, the
upper trough and enhanced southwesterly flow over the Rockies will
finally begin to overspread the Plains D4/Friday and D5/Saturday.
Continued east/southeasterly low-level flow is likely over the
northern Plains and Upper Midwest, allowing for the return of richer
surface moisture. A stalled front extending eastward from the lee
low over the Dakotas into the western Great Lakes may serve as a
focus for storm development across the Dakotas and MN. However,
models vary on the degree of moisture and resulting buoyancy near
the low/front, which casts significant uncertainty on severe
potential. Enhanced southwesterly flow aloft could support some
organized severe threat, but confidence in specifics remains too low
for 15% probabilities.

Farther south, sufficient destabilization is expected to support
isolated thunderstorms each afternoon into the central and southern
Plains. While the main upper trough should begin to weaken later
into the weekend, lingering mid-level flow could support some severe
risk within a hot and unstable air mass along a surface trough. By
early next week, mid-level ridging is expected to rebuild over the
central CONUS keeping stronger flow aloft and severe potential
limited for the remainder of the extended forecast period.

..Lyons.. 09/09/2025

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ACUS48 KWNS 100857
SWOD48
SPC AC 100856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Wed Sep 10 2025

Valid 131200Z - 181200Z

...DISCUSSION...
Severe potential in the extended forecast period will be tied to a
shortwave trough and stronger southwesterly flow aloft emanating
from the Rockies over the central US. Flow aloft will increase
D4/Saturday as the upper trough begins to overspread the central US.
Ascent from the trough will maintain a weak surface low and
stationary front over the northern Plains and Upper Midwest. At the
same time, a weak cold front will move eastward over the High Plains
serving as a focus for thunderstorm development from the Dakotas and
MN to the southern Plains each afternoon. Some isolated severe
potential is apparent near the surface low/stalled front over the
northern Plains and along the cold front farther south through the
remainder of the weekend. However, model guidance varies widely on
available moisture/buoyancy and the overlap with more robust
vertical shear. This continues to cast significant uncertainty on
severe probabilities through the first half of the extended forecast
period.

By early next week, mid-level ridging is expected to strengthen,
forcing stronger flow aloft northward as the primary western trough
begins to weaken. A second trough will stall over the West as the
ridge continues to build. This should favor drier surface conditions
while also limiting the overlap of buoyancy with stronger flow
aloft. Severe potential appears limited beyond this weekend and into
the first half of next week.

..Lyons.. 09/10/2025

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ACUS48 KWNS 110855
SWOD48
SPC AC 110854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Thu Sep 11 2025

Valid 141200Z - 191200Z

...DISCUSSION...
Model guidance is in fairly good agreement that the upper trough
over the central US will continue to lift northeastward into the
northern Plains and Upper Midwest through early next week. This will
drag a surface low and cold front slowly eastward with seasonably
high moisture in place. The low will begin to fill as it also lifts
into southern Canada. Scattered to numerous thunderstorms appear
likely over the Northern Plains and Upper Midwest, and along the
trailing front over the southern/central Plains each afternoon, as
increasingly meridional flow will parallel the slow moving cold
front. This will favor continued storm development/training along
the boundary with limited air mass destabilization/recovery.
Mid-level lapse rates should also weaken as the upper trough begins
to fill. While some marginal severe risk is evident over the
northern Plains near the low and front, mainly D4/Sunday,
significant uncertainty exists regarding boundary-layer
destabilization and its impacts on severe potential through
D5/Monday.

By D6/Tuesday, mid-level ridging behind the trough is forecast to
temporarily strengthen, weakening upper-level flow across the CONUS.
A second upper trough over the northern Rockies will begin to
approach behind the central US ridge, while a cutoff low develops
over the Southeast. This should limit broader overlap of instability
and stronger mid-level flow across much of the CONUS. Widespread
severe weather appears unlikely through next week.

..Lyons.. 09/11/2025

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ACUS48 KWNS 120759
SWOD48
SPC AC 120758

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 AM CDT Fri Sep 12 2025

Valid 151200Z - 201200Z

...DISCUSSION...
On Monday, a shortwave trough in the northern Plains will continue
to pivot northeast. The timing of this feature remains uncertain.
The ECMWF is the lone model that has a solution slow enough to have
some destabilization occur ahead of the trough. It is not clear how
much, if any, severe threat will exist in parts of central/northern
Minnesota.

On Tuesday, models indicate shortwave ridging will develop behind
the departing trough in the Upper Midwest. A secondary, broader
trough will be situated in the northern Rockies. Mid-level flow will
not be particularly strong, but embedded perturbations may provide
some enhancement. Depending on the quality of remaining moisture in
the Plains, some severe risk could develop along the surface trough
in the central High Plains. Uncertainty is high, however.

Through the remainder of the week, the upper-level pattern becomes
much more disorganized. Stronger flow may not return until the
weekend with a trough approaches the Northwest. Organized severe
potential appears to be low during this period.

..Wendt.. 09/12/2025

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ACUS48 KWNS 130756
SWOD48
SPC AC 130754

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 AM CDT Sat Sep 13 2025

Valid 161200Z - 211200Z

...DISCUSSION...
Weak mid/upper-level troughing should continue to move slowly
eastward from the northern Rockies/High Plains into the central
Plains and Upper Midwest from Day 4/Tuesday into Day 5/Wednesday.
Thunderstorms should develop across these regions both days as a
surface cold front likewise develops east-southeastward. While
moderate to locally strong instability may develop across the warm
sector each afternoon, mid-level flow and related deep-layer shear
are expected to remain rather modest. This should tend to limit
updraft organization and intensity to some extent, although
isolated/marginal severe potential may necessitate low severe
probabilities in later outlooks.

By late next week into the following weekend (Day 6/Thursday to Day 8/Saturday), medium-range guidance begins to diverge in its
depiction of the evolution of upper troughing across the Midwest/OH
Valley into the eastern CONUS. This lowers confidence in the
predictability of organized severe thunderstorms, but some potential
for strong thunderstorms may exist across portions of these regions
along/ahead of an advancing cold front.

..Gleason.. 09/13/2025

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ACUS48 KWNS 140739
SWOD48
SPC AC 140737

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0237 AM CDT Sun Sep 14 2025

Valid 171200Z - 221200Z

...DISCUSSION...
Organized severe thunderstorm potential appears low during the Day
4-8/Wed-Sun period. Medium range guidance is in fairly good
agreement that the upper shortwave trough over the northern/central
Plains Day 4 will develop an upper low as it meanders slowly east
toward the Mid/Upper MS Valley and the upper Great Lakes through
most of the forecast period. Some modest west/southwesterly
mid/upper flow ahead of the trough, in conjunction with a seasonally
moist boundary layer ahead of a southeastward-drifting cold front
could support sporadic strong storms across parts of the central
U.S. from the Ozarks to the Upper MS Valley mid to late in the week.
However, vertical shear is expected to remain poor, and the
slow-moving nature of the upper low and weakening surface front with time/eastward extent, will generally be unfavorable for a more
robust severe risk.

..Leitman.. 09/14/2025

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ACUS48 KWNS 150808
SWOD48
SPC AC 150806

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0306 AM CDT Mon Sep 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
An upper low/shortwave trough will persist over the north-central
U.S. for much of the period. This system is not forecast to deepen,
resulting in little surface cyclogenesis, with mainly weak surface
troughing persisting over the Plains. Southerly low-level flow will
maintain a seasonally moist airmass, and periods of showers and
thunderstorms are expected each day across parts of the Plains to
the MS Valley. Modest vertical shear and airmass modification from
daily rounds of convection will likely limit overall severe
potential.

Medium range guidance suggests by late in the period, around Day
8/Mon, a stronger surface cold front may sweep across portions of
the Plains as a deepening, more progressive upper trough moves from
the Rockies into the Plains.

..Leitman.. 09/15/2025

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ACUS48 KWNS 160810
SWOD48
SPC AC 160809

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0309 AM CDT Tue Sep 16 2025

Valid 191200Z - 241200Z

...DISCUSSION...
Severe thunderstorm potential is expected to remain low through at
least Day 6/Sun. A shortwave upper trough over the north-central
U.S. will slowly migrate east across the Great Lakes region through
the weekend. Weak deep layer flow and limited large-scale ascent
will preclude severe thunderstorms. By the end of the period, around
Days 7-8/Mon-Tue, medium range guidance suggests a more substantial
upper trough will eject from the northern Rockies and deepen over
the Plains/Midwest as a stronger surface cold front moves through
the central portions of the CONUS. This could support some
increasing severe thunderstorm potential, but large spread remains
across various forecast guidance regarding timing and evolution of
this feature as it develops east of the Rockies early next week.

..Leitman.. 09/16/2025

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ACUS48 KWNS 170800
SWOD48
SPC AC 170759

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 AM CDT Wed Sep 17 2025

Valid 201200Z - 251200Z

...DISCUSSION...
Medium-range guidance generally indicates low-amplitude/weak upper
troughing will persist across portions of the central U.S. through
the weekend. By early next week, large spread exists between the
control members of the GFS and ECMWF and how these models handle the
evolution of a deepening upper trough moving out of the Rockies and
into the Plains/Midwest around Days 6-8/Mon-Wed. Ensemble mean 500
mb forecasts are in better alignment, indicating a stronger
large-scale trough will emerge over the Plains and MS Valley late in
the period, bringing a stronger autumn cold front south/southeast
across much of the central U.S. This could bring some increasing
severe potential to portions of the Plains MS Valley during the
second half of the forecast period, but given aforementioned
uncertainty/large spread, it is unclear which days/locations may
experience any increasing risk.

..Leitman.. 09/17/2025

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ACUS48 KWNS 180750
SWOD48
SPC AC 180749

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 AM CDT Thu Sep 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
An upper shortwave trough is forecast to move across the northern
Rockies on Day 4/Sun while low-amplitude, broad upper troughing
persists across the central portion of the CONUS. By Day 5/Mon, the
northern Rockies upper trough is expected to rapidly deepen as it
overspread the plains. Rich boundary layer moisture if forecast to
be in place across portions of the southern/central Plains into the
MS Valley as a strong cold front moves across parts of the Plains.
While the timing of the upper trough ejecting into the Plains is
uncertain, some severe potential could develop on Day 5/Mon across
the southern/central Plains toward the Mid/Lower MO Valley.
Uncertainty remains too high to include 15 percent probabilities at
this time however.

Beyond Day 5/Mon, uncertainty increases as large spread among model
guidance persists with regard to the evolution of a developing upper
low somewhere over the mid-section of the CONUS into Day 8/Thu.
Severe potential is uncertain, and the overall pattern may favor
heavy rain over organized severe heading into Day 6/Tue, but model
trends will continue to be monitored.

..Leitman.. 09/18/2025

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ACUS48 KWNS 181410
SWOD48
SPC AC 181409

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0909 AM CDT Thu Sep 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
An upper shortwave trough is forecast to move across the northern
Rockies on Day 4/Sun while low-amplitude, broad upper troughing
persists across the central portion of the CONUS. By Day 5/Mon, the
northern Rockies upper trough is expected to rapidly deepen as it
overspread the plains. Rich boundary layer moisture if forecast to
be in place across portions of the southern/central Plains into the
MS Valley as a strong cold front moves across parts of the Plains.
While the timing of the upper trough ejecting into the Plains is
uncertain, some severe potential could develop on Day 5/Mon across
the southern/central Plains toward the Mid/Lower MO Valley.
Uncertainty remains too high to include 15 percent probabilities at
this time however.

Beyond Day 5/Mon, uncertainty increases as large spread among model
guidance persists with regard to the evolution of a developing upper
low somewhere over the mid-section of the CONUS into Day 8/Thu.
Severe potential is uncertain, and the overall pattern may favor
heavy rain over organized severe heading into Day 6/Tue, but model
trends will continue to be monitored.

..Leitman.. 09/18/2025

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ACUS48 KWNS 190852
SWOD48
SPC AC 190850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Fri Sep 19 2025

Valid 221200Z - 271200Z

...DISCUSSION...
A complex, split-flow, low-predictability upper pattern will exist
early next week and eventually evolve into a closed upper low across
the Midwest by the end of the week. The operational ECMWF and GFS
have significantly different evolution of the upper pattern.
However, the GEFS and EPS ensemble mean look very similar through
much of the extended forecast. Therefore, the operational GFS will
be treated as an outlier for this outlook cycle with an implied
preference for the ECMWF/EPS/GEFS.

...Day 4/Monday - TX/OK Panhandles into western Kansas and western
Oklahoma...
ECMWF forecast soundings on Monday show a favorable environment
featuring moderate to strong instability and moderate to strong
shear as a 40+ knot mid-level jet ejects across the TX Panhandle and
into Oklahoma. The primary trough will remain across the central
Rockies with only weak height falls across the Plains. However, a
strengthening low-level jet ahead of this trough may support
thunderstorm potential within this favorable zone. Relatively weak
synoptic support and lower predictability within the split-flow
regime precludes 15% probabilities at this time, but probabilities
may need to be included later, particularly if confidence in the
location and coverage of storms across portions of OK/KS and the TX
Panhandle increases.

...Day 5 and Beyond...
If a closed upper-low develops (as forecast by the GEFS and EPS
mean), some marginal severe weather concern will likely accompany
the low as it drifts east. No specific periods of greater severe
weather threat are apparent at this time, and given the slow forward
speed of the closed low, any severe weather threat will likely
remain marginal.

..Bentley.. 09/19/2025

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ACUS48 KWNS 200848
SWOD48
SPC AC 200846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Sat Sep 20 2025

Valid 231200Z - 281200Z

...DISCUSSION...
A complex, low-predictability upper pattern will exist next week and
should eventually evolve into a closed upper low somewhere across
the eastern CONUS by the end of the week. The operational ECMWF and
GFS have significantly different evolution of the upper pattern,
almost switching places from the solution each showed 24 hours ago.
The ECMWF is now more progressive with a large cutoff low from the
GFS by Wed/D5 and Thu/D6. Even the EPS and GEFS (which showed
similar 500mb solutions 24 hours ago) have diverged and have lead to
increasing predictability concerns. Therefore, beyond Day 4, some
severe weather chances are possible within the warm sector ahead of
a surface front. However, significant differences in timing and
evolution of the pattern cast uncertainty on the overall threat.

...Day 4/Tuesday...
As the stronger mid-level trough emerges across the Plains Monday
night, a low-level jet will strengthen across Oklahoma. Therefore, a
MCS will likely be ongoing at 12Z Tuesday in the Oklahoma vicinity.
Moderate destabilization is forecast to the south of the remnant
MCS/outflow boundary on Tuesday. This region will likely be the
focus for some severe weather threat. It is unclear how the
Monday/D3 convection will evolve and how that may impact Tuesday,
but there is some potential for severe storms Tuesday
afternoon/evening. Once the evolution of the mid-level trough and
location of Monday night convection becomes more clear, severe
weather probabilities may be needed.

..Bentley.. 09/20/2025

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ACUS48 KWNS 210741
SWOD48
SPC AC 210740

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 AM CDT Sun Sep 21 2025

Valid 241200Z - 291200Z

...DISCUSSION...
A mid-level trough will amplify across the eastern CONUS on
Wednesday and Thursday with differing model solutions of the trough
evolution by next weekend and beyond. Regardless of the exact
solution, severe weather chances should be low from Saturday and
beyond as high pressure builds into the eastern CONUS and pushes
moisture offshore into the Atlantic and Gulf. Some severe weather is
possible across portions of the Southeast on Day 4/Wed to Day 6/Fri
as moisture remains onshore ahead of the mid-level trough.

...D4/Wed - Lower Mississippi River Valley...
Upper 60s to low 70s dewpoints are anticipated within the Lower
Mississippi River Valley on Wednesday. A zone of moderate
instability may develop within this moisture plume from Louisiana
into Arkansas and Mississippi. Guidance varies greatly on the
evolution of the mid-level trough as it advances east on Wednesday.
This will have a significant impact on the specific location and
intensity of any severe weather threat on Wednesday. However, even
if a less amplified, more subdued mid-level pattern evolves, some
severe weather could exist across the Lower Mississippi Valley as
moderate mid-level flow overspreads moderate instability within the
region.

..Bentley.. 09/21/2025

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