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ACUS01 KWNS 201237

SWODY1

SPC AC 201235



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0735 AM CDT Sat Apr 20 2024



Valid 201300Z - 211200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON

THROUGH LATE EVENING ACROSS CENTRAL/SOUTH TX...AND FROM SOUTHERN MS

TO SOUTHERN NC...



...SUMMARY...

Marginally severe storms capable of strong wind gusts and hail will

be possible mainly this afternoon/evening across portions of central

and south Texas, and from southern Mississippi to southern North

Carolina.



...TX into the Southeast this afternoon/evening...

South of a midlevel trough over the Great Lakes, a southern-stream

shortwave trough will progress eastward from southern AZ/NM toward

the lower MS Valley by Sunday morning.  An associated surface

baroclinic zone from south TX into the Carolinas will move only

slowly southward through the period, providing a focus for isolated

to scattered thunderstorm development.  The more widespread

convection is expected across TX near and to the north of the front,

based on proximity to the richest moisture and the southern-stream

trough.



Boundary-layer dewpoints in the 60s and surface heating in cloud

breaks will drive MLCAPE in the 1000-2000 J/kg range immediately

south of the front across the Southeast this afternoon.  Vertical

shear will be relatively weak as a result of westerly wind profiles

with only modest speed increases from the low to midlevels.  The

moderate buoyancy, weak vertical shear and steep low-level lapse

rates will favor isolated strong/damaging outflow gusts for a few

hours this afternoon/evening.



Richer low-level moisture (dewpoints in the lower 70s) and steeper

midlevel lapse rates will be present across south TX through this

evening.  Initially elevated convection is expected to increase atop

the frontal surface from west central into central TX, and some of

this convection will approach the surface front this afternoon. 

Separate surface-based thunderstorm development is also expected

along the front, and the storms will subsequently spread

east-southeastward into early tonight.  Despite MLCAPE potentially

exceeding 2000 J/kg, the steeper lapse rates will be relatively high

in the profiles (above the 700 mb level), and vertical shear will

not be particularly strong.  Though isolated large hail and wind

damage will be possible, along with some clustering of storms later

this afternoon into early tonight, a MRGL risk (5% hail/wind and 2%

tornado) appears to best characterize the overall severe threat in

TX.



..Thompson/Kerr.. 04/20/2024



$$