Mesoscale Discussion 687

Issued

May 19, 2021, 2:10 PM CDT (19:10 UTC)

Expired

May 19, 2021, 4:45 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The San Angelo radar (KSJT), 122 km from the middle of the area, began a volume at 19:14 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

279 
ACUS11 KWNS 191910
SWOMCD
SPC MCD 191910 
TXZ000-192145-

Mesoscale Discussion 0687
NWS Storm Prediction Center Norman OK
0210 PM CDT Wed May 19 2021

Areas affected...Portions of west and west-central TX

Concerning...Severe potential...Watch unlikely 

Valid 191910Z - 192145Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated threat for severe hail and strong/gusty winds
may develop this afternoon. Watch issuance is unlikely.

DISCUSSION...Weak low-level upslope flow is occurring early this
afternoon across parts of west and west-central TX based on recent
surface observations and area VWPs. Diurnal heating has been fairly
muted across this region today given persistent mid/high-level cloud
cover in the wake of an expansive MCS and precipitation shield now
over coastal TX and the Gulf of Mexico. Still, surface dewpoints
generally in the low to mid 60s, coupled with steep mid-level lapse
rates noted on the 12Z MAF sounding, will likely support around
1000-2000 J/kg of MLCAPE in a fairly narrow corridor through the
remainder of the afternoon. Modest large-scale ascent associated
with a weakening upper trough over the southern High Plains should
encourage at least isolated additional storm development as
convective inhibition weakens with continued diurnal heating. Storms
may develop over the higher terrain of the Davis/Glass Mountains,
with other activity possible along a stalled front extending
southwest to northeast across west TX. Mid-level west-northwesterly
flow over this region is expected to remain fairly modest, generally
30-35 kt or less. Even so, there should be enough deep-layer shear
for some storm organization, with marginal supercells and small
clusters possible. Isolated instances of severe hail and
strong/gusty winds may occur with the more robust cores through the
rest of the afternoon. The eastward extent of the severe threat
across west-central TX should remain limited by convective
overturning from earlier storms. The overall severe threat currently
appears marginal/isolated, and watch issuance is unlikely.

..Gleason/Kerr.. 05/19/2021

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

ATTN...WFO...EWX...SJT...MAF...

LAT...LON   30380333 31420348 32240254 32500058 32469945 32109916
            31479903 30089979 29200084 29580138 29720187 29730229
            29640273 30070323 30380333

Mesoscale Discussions in Texas, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.