Mesoscale Discussion 581

Issued

May 10, 2021, 1:04 PM CDT (18:04 UTC)

Expired

May 10, 2021, 3:00 PM CDT

In force

116 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch likely

Chance of a watch

80%

Counties Edwards County, TX, Kinney County, TX, Real County, TX, Terrell County, TX, Val Verde County, TX

The Laughlin AFB radar (KDFX), 112 km from the middle of the area, began a volume at 18:08 UTC, the scan nearest the moment this went out.

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

• Severe Thunderstorm Watch 162May 10, 1:45 PM CDT

885 
ACUS11 KWNS 101804
SWOMCD
SPC MCD 101804 
TXZ000-102000-

Mesoscale Discussion 0581
NWS Storm Prediction Center Norman OK
0104 PM CDT Mon May 10 2021

Areas affected...Southern portions of the Edwards Plateau and
adjacent Rio Grande Valley

Concerning...Severe potential...Watch likely 

Valid 101804Z - 102000Z

Probability of Watch Issuance...80 percent

SUMMARY...Isolated to widely scattered thunderstorms are expected to
begin to initiate during the 2-4 PM CDT time frame, if not before. 
Some of these may undergo a period of rapid intensification by late
afternoon, with large, damaging hail (up to 3-4+ inches in diameter)
the most prominent hazard, at least initially.

DISCUSSION...Beneath warm and capping elevated mixed-layer air,
daytime heating within a very moist boundary layer is contributing
to strong destabilization, along and south of the shallow leading
edge of cool surface-based air which has reached the Pecos River
vicinity into southern portions of the Edwards Plateau/Hill Country.
 Objective analysis suggests CAPE now exceeds 3000 J/kg, in the
presence of strong deep-layer shear beneath a 50-60+ kt,
west-southwesterly subtropical jet.

Persistent attempts at deep convective development have been ongoing
in response to focused low-level convergence along the surface front
across Val Verde and Edwards counties, with initial attempts at
convective development also underway across the higher terrain of
northern Coahuila.  There is considerable signal in the various
model output that scattered thunderstorms may begin to initiate
during the 19-21Z time frame, perhaps aided by a subtle mid-level
perturbation progressing across and east of the Texas Big Bend
vicinity.

Given the environment, once storms initiate, rapid intensification
into supercells is possible, with strongest storms becoming capable
of producing very large, damaging hail and locally strong surface
gusts, as well as perhaps posing some risk for a tornado.

..Kerr/Thompson.. 05/10/2021

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

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

LAT...LON   29670257 29930226 30620207 30520166 30280119 30399978
            29549960 29290043 29150071 28440084 28280195 29050215
            29670257

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.