506
ACUS01 KWNS 291243
SWODY1
SPC AC 291241

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Wed May 29 2024

Valid 291300Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
THROUGH LATE EVENING ACROSS THE NORTHERN/CENTRAL HIGH PLAINS AND IN
SOUTHWEST TX...

...SUMMARY...
Scattered strong storms posing a risk for severe hail and wind
appear likely across the northern and central High Plains late this
afternoon and evening. Isolated large hail will also be possible in
southwest Texas.

...Northern/central High Plains this afternoon into tonight...
A midlevel shortwave trough over the northern Rockies will continue
eastward with associated lee troughing expected across the
northern/central High Plains through the afternoon/evening.  A
corridor of modest low-level moistening (boundary-layer dewpoints
potentially into the 50s) will occur along and east of the lee
trough, where afternoon surface temperatures will warm well into the
80s beneath steep midlevel lapse rates and result in SBCAPE of
1000-2000 J/kg with minimal convective inhibition.  Scattered
high-based thunderstorms are expected to form by mid afternoon near
the lee trough and spread eastward through late evening, with some
potential for storms to be maintained into tonight in association
with a strengthening low-level jet and warm advection.  Occasional
severe outflow gusts of 60-70 mph and isolated large hail of 1-1.5
inches in diameter will be the main threats with primarily multicell
clusters and possibly some weak supercell structures given
weak-modest deep-layer vertical shear (effective shear generally
25-30 kt).

...Southern Plains today into tonight...
Widespread convective overturning has occurred across TX in the past
24 hours, with the remnants of a large MCS now weakening just off
the lower TX coast.  Lingering low-level moisture and steep lapse
rates across the Trans-Pecos (northwest of the MCS remnants) could
support isolated thunderstorm development this afternoon near the
Davis Mountains.  Here, MLCAPE in excess of 2000 J/kg and
sufficiently long hodographs will favor splitting supercells capable
of producing isolated large hail, potentially 2 inches in diameter
or larger.

Otherwise, marginally severe storm development may occur near the
upper TX coast later today with a remnant MCV on the edge of the
richer low-level moisture.  The southern portion of the central High
Plains convection may persist through tonight and grow into a
loosely organized MCS from western KS southward into the TX
Panhandle and western OK, where the storms will encounter gradually
increasing low-level moisture in a warm advection regime.  A few
strong gusts and isolated/marginally severe hail may occur with the
strongest embedded storms.

...Central Appalachians/Mid-Atlantic this afternoon...
A midlevel trough now over OH will progress eastward to the
Mid-Atlantic coast by early tonight.  Low-level moisture will be
relatively limited in advance of the midlevel trough and a weak
surface reflection, but surface heating and steepening of low-level
lapse rates will contribute to weak SBCAPE of 250-500 J/kg.
Scattered, low-topped thunderstorms will be possible this afternoon
across PA/MD/VA and convection will spread to the coast this
evening.  The steep low-level lapse rates will promote gusty outflow
winds, but severe/damaging winds appear unlikely given marginal
buoyancy and weak low-level flow to limit momentum transfer.

..Thompson/Grams.. 05/29/2024

$$