ACUS02 KWNS 211721
SWODY2
SPC AC 211720

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 PM CDT Mon Apr 21 2025

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS AND INTO PARTS OF SOUTHERN KANSAS...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible on Tuesday
across portions of the southern Plains.

...Synopsis...
A mostly zonal pattern will be in place across the CONUS with
multiple embedded weak shortwave troughs on Tuesday. One such trough
which is forecast to move across New Mexico during the afternoon may
result in some weak lee troughing and support the potential for
isolated to scattered severe storms along the dryline Tuesday
afternoon.

...Southern High Plains...
Low-level moisture will advect northward across West Texas ahead of
a dryline Tuesday morning. Strong surface heating will lead to
moderate to strong destabilization along and ahead of the dryline.
Forecast soundings show a weakly capped airmass which should be
sufficient for isolated to scattered thunderstorm development by mid
to late afternoon as weak forcing from the mid-level trough
overspreads the dryline. 30 to 35 knots of shear should support
high-based, slow-moving supercells with a threat for large hail and
severe wind gusts. An isolated tornado threat may also exist where
better low-level moisture is present, farther south, and where
intersecting boundaries could enhance low-level vorticity ingestion.

Upscale growth may eventually occur with one or more MCSs moving
east into the evening and overnight hours, supported by a modestly
enhanced low-level jet.

...Northern Panhandle into Kansas...
A surface front is forecast to extend across Kansas and into the
OK/northern TX Panhandle by Tuesday afternoon. Only modest moisture
recovery will occur this far north, but it may be sufficient for
moderate instability along the front by mid-afternoon. 25 to 30
knots of shear will support some storm organization. Very steep
lapse rates and a relatively dry profile will support the potential
for isolated large hail and severe wind gusts.

...IA/WI/IL...
A stalled frontal boundary will be in place across the Mid-MO Valley
into southern WI on Tuesday. Modest moisture return and persistent
isentropic ascent along this boundary may be sufficient for isolated
thunderstorm development amid weak diurnal destabilization. Low to
midlevel flow will remain rather weak, but rapidly increase above
700 mb, supporting effective shear magnitudes greater than 40 kt.
Cold temperatures aloft (-17 C near 500 mb) will support MLCAPE to
around 500 J/kg, and isolated convection could produce sporadic hail
or damaging wind gusts.

...Carolinas...
A cold front associated with a surface low over Quebec will move
southeast across the Mid-Atlantic and Carolinas during the
afternoon/evening. Strong heating of a modestly moist boundary layer
ahead of the front will support a corridor of MLCAPE up to 1000-1500
J/kg. Weak low-level southwesterly flow will increase with height,
support effective shear magnitudes up to 35 kt. This should be
sufficient for a few stronger/organized cells. Steep low-level lapse
rates and somewhat elongated hodographs suggest transient supercells
capable of strong gusts and isolated hail will be possible. In
addition, any storms which interact with the sea breeze could have
locally enhanced updrafts and a periodically greater large
hail/damaging wind threat.

..Bentley.. 04/21/2025

$$