SPC MD 499

SPC MD 499


Mesoscale Discussion 0499
NWS Storm Prediction Center Norman OK
0136 PM CDT Sat Apr 20 2024

Areas affected…Texas Coastal Plain into Southeast TX

Concerning…Severe potential…Watch unlikely

Valid 201836Z – 202100Z

Probability of Watch Issuance…20 percent

SUMMARY…Widespread thunderstorms are expected from the Texas
Coastal Plain into Southeast TX this afternoon. Isolated strong to
severe thunderstorms are possible, with hail to 1″ in diameter and
damaging gusts from 45 to 55 mph as the primary hazards.

DISCUSSION…A cold front continues to push slowly south across
central and east TX, aided by a widespread showers and thunderstorms
from southwest TX through north-central and into northeast TX. Warm
and moist southerly low-level flow has persisted throughout the
morning and into to early afternoon. This has resulted in increased
low-level convergence along the front zone while also destabilizing
the downstream air mass. Pre-frontal dewpoints now range from the
upper 60s across the TX Hill Country to the low 70s across the TX
Coastal Plain into southeast TX. Additionally, filtered heating has
allowed temperatures to rise into the low 80s. These low-level
thermodynamic conditions have resulted in air mass destabilization,
with mesoanalysis recently estimating that convective inhibition has
eroded. Additionally, these warm and moist conditions are
contributing to moderate buoyancy (i.e. around 1500 J/kg) despite
relatively poor mid-level lapse rates.

General expectation is for thunderstorm coverage to increase this
afternoon along and ahead of the front. Widespread coverage should
limit storm discreteness while boundary-parallel deep-layer vertical
shear favors multicell clusters. Even so, Given the moderate
buoyancy and shear, a few stronger storms are possible. The
strongest storms may be able to produce hail up to around 1″. A few
water-loaded downbursts from 45 to 55 mph are possible as well.

..Mosier/Goss.. 04/20/2024

…Please see www.spc.noaa.gov for graphic product…


LAT…LON 29299870 30079704 30809547 30609473 29759465 27989757
28209929 29299870

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