MD 0301 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF FAR SOUTHERN TEXAS
Mesoscale Discussion 0301
NWS Storm Prediction Center Norman OK
1010 PM CDT Mon Mar 21 2022
Areas affected...portions of far southern Texas
Concerning...Severe potential...Watch unlikely
Valid 220310Z - 220445Z
Probability of Watch Issuance...20 percent
SUMMARY...An isolated large hail threat may develop with a discrete
storm in Webb County Texas. However, coverage and longevity of
thunderstorms in this area are in question, and a WW issuance does
not seem likely at this time.
DISCUSSION...A discrete thunderstorm/potential supercell structure
has rapidly developed in Webb County, Texas over the last hour, with
MRMS MESH data suggesting up to 2 inch hail may by occurring with
this storm. This very isolated supercell has developed immediately
ahead of the dryline, likely due to intense mixing given the
presence of an intense cap around 850 mb per 00Z BRO and CRP
observed soundings. Nonetheless, adequate buoyancy resided
immediately above the capping inversion, with the aforementioned
observed soundings showing 9 C/km 850-600 mb lapse rates.
Nonetheless, the presence of such strong capping casts doubt on a
more widespread severe event. The last few runs of the HRRR and
multiple members of the 0200 and 0230Z Warn-on-Forecast ensemble
output depict initially robust updrafts, followed by weaker
upscale-growing convection across deep south Texas in the 03-06Z
period. As such, current thinking is that sparse, but severe hail
will accompany the ongoing storm in the short term and a WW issuance
is not expected.
..Squitieri.. 03/22/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...
LAT...LON 27349946 27869936 28319894 28599847 28689777 28599725
28379711 28079723 27839753 27459873 27349946
