Mesoscale Discussion 0502
NWS Storm Prediction Center Norman OK
0746 PM CDT Sat Apr 20 2024
Areas affected...South-central into deep south TX
Concerning...Severe potential...Watch possible
Valid 210046Z - 210215Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated severe storms may evolve with time this evening,
with a threat of large hail and localized severe gusts.
DISCUSSION...Elevated convection has recently increased in coverage
and intensity north of a cold front across western portions of
south-central TX, with recent initiation noted farther south near a
stationary front, north of Laredo. Confidence in greater storm
coverage this evening is higher with northward extent, where
elevated convection may continue to evolve within an environment
characterized by MUCAPE of 1000-1500 J/kg (as noted in the 00Z DRT
sounding) and sufficient effective shear for some storm
organization. Isolated hail will be possible within this regime as
storms spread eastward with time.
Near-term storm potential farther south remains more uncertain, with
generally nebulous large-scale ascent across the region, and some
nocturnal cooling/stabilization expected with time. However, the
environment south of the deeper post-frontal cold air is
conditionally favorable for severe storms, with steep midlevel lapse
rates atop rich low-level moisture supporting MLCAPE in excess of
2000 J/kg. If a supercell can evolve within this regime, there would
be at least an isolated threat of large to very large hail
(approaching 2 inches in diameter), along with some threat for
severe gusts with convection that remains rooted closer to the
surface. Watch issuance is possible, if supercell development within
this more favorable environment appears imminent.
..Dean/Guyer.. 04/21/2024
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...BRO...
LAT...LON 28050022 28520043 29779985 29769811 28009808 27019871
26799929 27129981 28050022
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