Mesoscale Discussion 1792

Issued

Sep 30, 2021, 10:38 AM CDT (15:38 UTC)

Expired

Sep 30, 2021, 1:15 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Midland/Odessa radar (KMAF), 141 km from the middle of the area, began a volume at 15:37 UTC, the scan nearest the moment this went out.

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• Severe Thunderstorm Watch 511Sep 30, 12:45 PM CDT

432 
ACUS11 KWNS 301539
SWOMCD
SPC MCD 301538 
TXZ000-NMZ000-301815-

Mesoscale Discussion 1792
NWS Storm Prediction Center Norman OK
1038 AM CDT Thu Sep 30 2021

Areas affected...Parts of southwestern Texas and adjacent portions
of New Mexico into parts of the Texas South Plains

Concerning...Severe potential...Watch possible 

Valid 301538Z - 301815Z

Probability of Watch Issuance...40 percent

SUMMARY...Increasing strong thunderstorm development is possible
across the mountains of southwest Texas, and perhaps
east-northeastward into the I-20 corridor of the Texas South Plains,
as early as 1-3 PM CDT.  Before activity becomes increasingly
widespread, stronger storms may pose a risk for large hail, with
some potential for locally strong surface gusts.

DISCUSSION...Within broad but weak mid-level troughing across the
Intermountain West into Great Plains, a smaller-scale impulse is now
in the process of pivoting eastward/northeastward into the southern
Rockies.  As this continues, weak near-surface/low-level wind fields
will continue to back to the southeast, ahead of a cold front
advancing toward the Interstate 20 corridor of the Texas South
Plains.  It appears that this will contribute to further westward
advection of low-level moisture (including surface dew points as
high as mid 60s F+), and some increase of generally weak current
shear beneath 20-40+ kt southwesterly flow in the 500-300 mb layer. 
In the presence of modestly steep mid-level lapse rates, mixed-layer
CAPE is forecast to increase in excess of 2000 J/kg during the next
few hours.

As inhibition weakens with large-scale ascent aided by increasingly
divergent high-level flow, as well as additional surface heating, it
appears that boundary-layer based thunderstorms may begin initiating
by early afternoon across the mountains of southwest Texas, and
perhaps east-northeastward along the front, near/north of Odessa,
Midland and Big Spring.  As this occurs, before storms become
increasingly widespread, the environment probably will become
conducive to large hail in the stronger cells.

..Kerr.. 09/30/2021

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

ATTN...WFO...SJT...MAF...EPZ...

LAT...LON   29690431 30780495 31290506 31580476 31870451 31890360
            32230289 32960044 32139943 31190201 30150221 29180211
            28770314 29690431

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.