ACUS02 KWNS 180552
SWODY2
SPC AC 180550

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Sat May 18 2024

Valid 191200Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF WESTERN AND CENTRAL KANSAS...

...SUMMARY...
Severe thunderstorms are most likely across parts of Kansas Sunday
afternoon and evening. Significant damaging gusts, large to very
large hail, and a few tornadoes all appear possible.

...NE/KS/OK...

A weak upper shortwave impulse over NE Sunday morning will quickly
lift northeast. Some convection may be ongoing across NE/KS during
the morning, but is forecast to quickly weaken/shift east. This
early activity may suppress severe potential across northeast NE
during the afternoon as airmass recovery is uncertain. By afternoon,
another upper shortwave trough is forecast to eject from the
southern/central Rockies into KS, and then the Lower MO Valley by
Monday morning. This secondary shortwave trough will be the focus
for the primary severe risk during the afternoon/evening.

A surface dryline is forecast to extend southward from near the
NE/KS/CO border into western KS and then near the OK/TX border. To
the east of the dryline, dewpoints into the low/mid 60s are expected
across OK into central/eastern KS (somewhat lower across northern KS
and southern NE). Very steep midlevel lapse rates (greater than 8
C/km) will be in place. Capping will suppress convection until
mid/late afternoon, when large-scale ascent increases amid strong
heating and continued warm/moist advection. High-based storms along
the dryline will initially pose a risk of large hail and damaging
gusts. Forecast guidance (including HREF and CAMs) show a strong
signal for upscale growth into an intense bow is possible across KS.
Upscale growth is possible via consolidating outflow and an
increasing low-level jet during the late afternoon/early evening.
Significant gusts will be possible if this scenario evolves as
expected. Large to very hail and a few tornadoes also will be
possible. Hail greater than 2 inches in diameter will be possible
early in convective evolution, but eastward extent of this risk is
uncertain and dependent on storm mode.

Severe potential southward along the dryline into western OK is more
uncertain and conditional. If a storm can develop and be maintained,
all severe hazards would be possible, particularly very large hail
and damaging gusts.

...SD vicinity...

Southerly low-level flow will transport mid/upper 50s F dewpoints
northward into northern NE/SD and southern ND. A cold front is
forecast to develop eastward during the late Sunday afternoon into
Sunday night. Steep midlevel lapse rates will be in place, but an
EML will likely limit a greater severe risk. Nevertheless, MUCAPE to
around 1500 J/kg will support elevated convection ahead of the cold
front. Isolated hail will be the main risk. However, if an organized
line of storms can develop, some gusty winds also are possible.

...Lower MO Valley toward the Mid-MS Valley...

Convection from NE/KS may dissipate over the area during the
morning. However, a warm front is expected to slowly lift northward
through the day, allowing from some airmass recovery and
destabilization. Convection may redevelop near this boundary during
the afternoon. This activity may produce marginally severe hail and
gusty winds.

...FL...

An upper trough from the Mid-Atlantic to the northern Gulf will
shift east over the Atlantic on Sunday. A belt of enhanced
west/southwesterly flow (30-40 kt at 700 mb) will overspread the FL
peninsula ahead of the trough. Mid to upper 60s F surface dewpoints
and strong heating will contribute to MLCAPE values around 1500-2500
J/kg. Steep low-level lapse rates will support isolated strong gusts
in water-loaded downdrafts. Elongated/straight forecast hodographs
and modest midlevel lapse rates (6.5-7 C/km) suggest isolated large
hail also is possible. Effective shear around 30 kt suggests
organized updrafts may be somewhat transient. If confidence
increases regarding coverage of organized severe convection, higher probabilities may be needed in subsequent outlooks.

..Leitman.. 05/18/2024

$$
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ACUS02 KWNS 181742
SWODY2
SPC AC 181741

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 PM CDT Sat May 18 2024

Valid 191200Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
WESTERN AND CENTRAL KANSAS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE EAST COAST OF FLORIDA...

...SUMMARY...
Severe thunderstorms are most likely across parts of Kansas Sunday
afternoon and evening. Significant damaging gusts, large to very
large hail, and a few tornadoes all appear possible. Large hail is
also probable along parts of the east coast of Florida.

...Synopsis...
A shortwave trough will slowly exit the southeastern U.S. coast on
Sunday. Across the West, another broad upper-level trough will
intensify and dig southward. Shortwave perturbations are expected to
eject into the central Plains early Sunday morning and near the
Raton Meso into western Kansas later in the afternoon. At the
surface, a weak surface low will move through southeastern Georgia
into North Florida. A surface boundary may sag farther southward
into the Florida Peninsula along with a sea breeze front developing
by the afternoon. In the High Plains, two surface lows will deepen,
one in the southern High Plains and another in the central High
Plains near the Black Hills.

...Central into Southern Plains...
Some convection is expected to be ongoing early in the period along
the Kansas/Nebraska border into eastern Nebraska in association with
a low-level jet and the weak shortwave trough moving through the
region. This activity will shift north and east with time as the
trough passes. By the afternoon, a dryline forecast to develop from
southwest Kansas into the Texas Panhandle/western Oklahoma. A
capping inversion should keep development from occurring until the
secondary shortwave ejects during the afternoon. Storms that
initially develop in Kansas will likely be supercells capable of all
severe hazards, including very large hail. The uncertainty in this
scenario will be how long storms will remain discrete. Storms that
can form farther east along the dryline would have the greatest
potential to remain discrete for longer. However, there is a signal
for convection to develop within the Raton Mesa and eventually
intensify as it encounters greater surface moisture to the east.
These storms would likely be more outflow dominant initially and
could lead to the quicker clustering that most guidance shows in
Kansas. Forecast soundings from CAMs show strong cold pool
development and hints of a strong rear inflow jet, suggesting
potential for a strong MCS capable of significant wind gusts.

Farther south into western Oklahoma, storm coverage is much less
certain on account of stronger capping and weaker forcing. Should a
storm develop, all severe hazards would be possible. Currently, a
discrete storm appears most likely in northwest Oklahoma on the
southern fringe of the mid-level ascent.

...Florida...
Storms appear likely to develop along the southward sagging surface
boundary. However, strong heating is expected along the east coast
of Florida with storms forming along the sea breeze in the
afternoon. With the generally favorable timing of the shortwave
trough, shear should be sufficient for supercells and temperatures
aloft should be cold enough (around -10 C) to support a threat for
large hail. Farther west, storms are not expected to be as
organized, but isolated damaging winds and large hail are still
possible.

...Western Nebraska/western South Dakota...
The northern surface low will deepen and help advect mid to perhaps
upper 50s F dewpoints into the region. Storms are expected to
develop during the afternoon. Large hail and severe wind gusts will
be the main hazards. The larger surface temperature/dewpoint spreads
and weaker shear than farther south may lead to less organized
storms. As such, will continue with a Marginal hail/wind risk.

..Wendt.. 05/18/2024

$$
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