Mesoscale Discussion 590

Issued

May 11, 2021, 10:13 AM CDT (15:13 UTC)

Expired

May 11, 2021, 11:15 AM CDT

In force

62 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Dallas/Ft Worth radar (KFWS), 121 km from the middle of the area, began a volume at 15:15 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.

845 
ACUS11 KWNS 111514
SWOMCD
SPC MCD 111513 
TXZ000-111615-

Mesoscale Discussion 0590
NWS Storm Prediction Center Norman OK
1013 AM CDT Tue May 11 2021

Areas affected...Parts  of central through northeast Texas

Concerning...Severe potential...Watch possible 

Valid 111513Z - 111615Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms are expected to continue to initiate and
become increasingly widespread north through northeast of the
Edwards Plateau and adjacent Big Country through the Interstate
30/20 corridors by Noon to 2 PM CDT.  This may include at least some
risk for severe hail early, with potential to organize later this
afternoon, if not before.  It is not yet certain a watch will be
needed, but trends will continue to be monitored for this
possibility.

DISCUSSION...Latest model output indicates a substantial
strengthening of large-scale ascent north/northeast of the Edwards
Plateau, across parts of the Texas Big Country through the
Interstates 30/20 corridors of north central and northeast Texas by
17-19Z.  This is forecast to occur in response to strengthening
lower/mid-tropospheric warm advection, beneath increasingly
divergent high-level flow, as a west-southwesterly subtropical jet
streak continues to nose across the northern Mexican Plateau through
the Texas Gulf coast vicinity.

This lift will largely be focused above at least shallow cool/stable
surface-based air to the north of stalled/slow moving frontal zone
now extending across the upper Texas coastal plain through parts of
Deep South Texas and the lower Rio Grande Valley.  However,
seasonably moist air above the frontal inversion, and beneath steep
lapse rates associated with elevated mixed-layer air, is
contributing to moderate to large CAPE, supportive of vigorous
thunderstorm development.

While high-level flow is strong, lower/mid tropospheric flow is
somewhat modest to weak.  Coupled with the likelihood for
increasingly widespread convection through midday and early
afternoon, hail potential in the longer term remains unclear. 
However, given the initial thermodynamic profiles, there may be a
window of opportunity for large hail in the initially more discrete
early storm development.

..Kerr/Thompson.. 05/11/2021

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

ATTN...WFO...SHV...HGX...FWD...EWX...SJT...

LAT...LON   32609949 32959809 33149610 32439453 31079569 30959757
            30349983 30570081 31300040 32609949

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.