Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 1786

September 27, 2021Brewster County, Pecos County, Presidio County, Texas

The Storm Prediction Center issued this mesoscale discussion at Sep 27, 2021, 3:12 PM CDT for Brewster County, Pecos County, Presidio County, Texas. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Sep 27, 2021, 3:12 PM CDT (20:12 UTC)
Expired: Sep 27, 2021, 4:45 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Brewster County, TX, Pecos County, TX, Presidio County, TX

The radar

The Midland/Odessa radar (KMAF), 226 km from the middle of the area, began a volume at 20:12 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.

The nearest sounding before it

Midland Regional, TX (KMAF), launched 12:00Z, 8.2 hours before the alert went out and 226 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 6 J/kg
Mixed-layer CIN: -364 J/kg
Mixed-layer LCL: 1521 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: -136 m²/s²
0-3 km storm-relative helicity: -54 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

094 
ACUS11 KWNS 272013
SWOMCD
SPC MCD 272012 
TXZ000-272145-

Mesoscale Discussion 1786
NWS Storm Prediction Center Norman OK
0312 PM CDT Mon Sep 27 2021

Areas affected...portions of the Trans Pecos

Concerning...Severe potential...Watch unlikely 

Valid 272012Z - 272145Z

Probability of Watch Issuance...5 percent

SUMMARY...Storms are starting to develop. These storms may pose a
threat for isolated large hail and severe winds.

DISCUSSION...Storms have started to develop in a confluence zone
within the Trans Pecos with low-level convergence greatest west of
Fort Stockton where terrain circulations are maximized. Instability
is currently somewhat limited with MLCAPE around 500 J/kg per SPC
mesoanalysis. However, temperatures are expected to warm further in
the area with greater instability developing through the afternoon
and into the evening. As instability increases, storm intensity is
also expected to increase.

SPC mesoanalysis shows effective shear around 35 knots in the region
with very straight hodographs. This should support storm
organization including the potential for splitting supercells.
Isolated large hail and severe wind gusts are possible with these
storms, but the limited instability and somewhat isolated nature of
the threat will likely preclude the need for a watch.

..Bentley/Thompson.. 09/27/2021

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

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

LAT...LON   30300480 30970344 30950192 30600159 29840271 29520443
            29760468 30300480

Nearby

Mesoscale Discussions in Texas, 2021 Every mesoscale discussion in 2021

Sources

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.