ACUS01 KWNS 251252
SWODY1
SPC AC 251250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Sat Apr 25 2026

Valid 251300Z - 261200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/EASTERN OKLAHOMA AND FAR NORTH TEXAS...

...SUMMARY...
Severe thunderstorms with very large to giant hail (2 to 4+ inches
in diameter), tornadoes, and scattered damaging winds are expected
late this afternoon through tonight across parts of the southern
Plains and ArkLaTex. A couple of strong tornadoes are possible.

...Synopsis...
A closed mid/upper-level low will remain centered over Manitoba and Saskatchewan today, while generally zonal/westerly mid-level winds
persist over the southern Plains. A weak shortwave trough over the Southwest/southern Rockies this morning is forecast to eject
eastward over the southern/central Plains by late this afternoon. At
the surface, a convectively reinforced outflow boundary draped
across north-central/northeast TX will shift northward into OK as a
warm front today, while a low gradually deepens over northwest TX by
late afternoon/early evening. Rich low-level moisture characterized
by upper 60s to low 70s surface dewpoints will likely advance as far
north as central into southeast OK through peak diurnal heating,
with lesser moisture return farther north into northwest OK, KS, and
southeast NE ahead of a cold front. A dryline will extend
south-southwestward from the surface low across central into
south-central TX.

...Southern/Central Plains into the ArkLaTex...

Strong to locally extreme instability (MLCAPE 2500-4000+ J/kg) is
expected to develop along/east of the dryline in TX and south of the
warm front in OK by peak afternoon heating. The presence of
seasonably cool temperatures aloft and 7.5-8.5 C/km mid-level lapse
rates will also support this very favorable thermodynamic
environment. While large-scale ascent associated with the ejecting
mid-level shortwave trough is not expected to be overly robust, it
should be sufficient for at least isolated thunderstorm initiation
by mid afternoon to early evening (around 20-23Z), especially near
the warm front/dryline intersection in south-central OK.

40-50 kt of generally westerly effective bulk shear will support
intense supercells, with multiple right/left splits likely. This
activity will quickly intensify shortly after convective initiation,
and very large to giant hail appears likely (2-4+ inches in
diameter). The Enhanced/Moderate Risk areas have been expanded
slightly in OK and north TX to account for deviant thunderstorm
motions and the potential for multiple intense supercells to track east-southeastward along/near the warm front. A conditional risk for
supercells remains apparent farther south along the length of the
dryline in TX, although confidence in convective initiation remains
low. Have maintained the Marginal Risk for this potential, with some
expansion eastward in case isolated thunderstorms do initiate.

Modest southerly low-level winds (around 20-30 kt at 850 mb) will be
present through this evening across the southern Plains. Locally
enhanced 0-1 km SRH will be present near the warm front with backed near-surface winds. This will support a threat for tornadoes with
any right-split supercells that can remain surface based. A slight
increase in the low-level jet this evening and presence of very
strong to locally extreme buoyancy also suggests some threat for a
couple of EF-2+ tornadoes. With time this evening, convection may
grow upscale and pose a threat for scattered severe/damaging winds
as it spreads southeastward into the ArkLaTex.

Farther north in KS/NE, instability and low-level moisture is
expected to remain weaker/more limited. But, some supercells/small
clusters may eventually develop this afternoon and move
east-northeastward given sufficient deep-layer shear for updraft
organization. Isolated to scattered severe hail and damaging winds
should be the main threat with this activity through mid evening
before it eventually weakens.

...Lower Mississippi Valley/Central Gulf Coast...

A long-lived convective cluster has nearly moved offshore from the
coast of AL/MS/LA. In its wake, a rain-cooled airmass exists across
much of the lower MS Valley. This should hinder the development of
much surface-based instability through early afternoon. Still,
eventual re-destabilization should occur along/near the remnant
outflow boundary. Isolated cells that may develop could pose some
risk for hail and damaging winds.

..Gleason/Thompson.. 04/25/2026

$$

--- ScorpioBBS/QWK v0.32a (Linux/x86_64)
* Origin: Project Scorpio TEST (618:250/6)

ACUS01 KWNS 181246
SWODY1
SPC AC 181244

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Mon May 18 2026

Valid 181300Z - 191200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/NORTHEAST KANSAS...SOUTHEAST NEBRASKA...AND FAR NORTHWEST MISSOURI...

...SUMMARY...
Numerous severe thunderstorms are expected this afternoon and
evening across the south-central Plains and mid Missouri Valley.
Supercells capable of producing very large to giant hail and
multiple strong to intense tornadoes are most likely from central
Kansas and southeast Nebraska into Iowa and northwest Missouri.

...Central Plains into the Midwest/Great Lakes...

Extensive convection continues this morning from western IL into MO
and far eastern KS, aided by warm/moist advection associated with a
40-50 kt southwesterly low-level jet. Gradual destabilization of the
airmass downstream of this ongoing activity is expected today across
the mid MS Valley and Midwest/OH Valley/Great Lakes. Some potential
exists for re-intensification of one or more bowing clusters, with
scattered damaging winds the main concern as low-level lapse rates
gradually steepen. Somewhat less instability and more modest
mid-level flow and related deep-layer shear with eastward extent
into the OH Valley should induce gradual weakening with these
clusters this evening.

The outflow boundary from the morning convection across KS will
likely play a key role in determining the northern extent of
appreciable severe risk later today across the central Plains into
the mid MO Valley. There is concern that this boundary's continued
southward movement this morning and ongoing convection to its north
may hinder/delay destabilization this afternoon ahead of the surface
cold front/dryline. Still, strengthening mid-level flow and
large-scale ascent associated with an ejecting shortwave trough is
expected to overspread the developing warm sector across central KS
into southeast NE by mid to late afternoon.

Even with potential limiting factors such as outflow boundary
placement and residual cloud cover, the presence of very steep lapse
rates aloft (reference 12Z DDC observed sounding) and daytime
heating of a rather moist low-level airmass will likely support
strong to possibly extreme instability south of the cold front and
east of the dryline by early afternoon. Most guidance continues to
suggest that robust thunderstorm initiation will occur by 18-22Z
across central/northeast KS into far southeast NE. These initial
supercells should pose a threat for very large to potentially giant
hail (2-4+ inches in diameter). As low-level shear gradually
increases through late afternoon/early evening in tandem with a
strengthening southerly low-level jet, a focused spatial/temporal
corridor for strong to intense tornadoes should exist across parts
of central/northeast KS into far southeast NE and northwest MO.

Fairly quick upscale growth appears likely by mid to late evening as thunderstorm mergers/interactions occur, and as the cold front
advances east-southeastward. Even so, a continued threat for QLCS
and embedded supercell tornadoes should continue, as low-level shear
will remain enhanced by a 50+ kt low-level jet. Severe/damaging
winds will also become an increasing concern as convection spreads
eastward in tandem with the cold front. Some severe wind threat may
persist through much of the night since ample instability is
forecast to exist ahead of convection, especially across KS/MO/OK.

...Southern Plains...

Thunderstorm initiation along the dryline this afternoon/early
evening across western OK into western north TX is more uncertain
than locations farther north given expectations for more limited
forcing for ascent. If/where convection does form, there is the
potential for very large hail and a conditional risk for tornadoes
with any persistent supercells, given the presence of steep
mid-level lapse rates, strong instability, moderate deep-layer
shear, and gradually increasing low-level shear this evening. But,
weaker winds above 400 mb by late afternoon/evening may not be
overly favorable for long-lived convection, even if it does form.

...Mid-Atlantic/Northeast...

Influenced by terrain and a surface trough, isolated strong to
severe thunderstorms capable of producing occasional wind damage may
occur this afternoon within a moderately unstable environment.

..Gleason/Marsh.. 05/18/2026

$$

--- Scorpio BBS
* Origin: (618:250/6)