Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 829

May 31, 2021Brewster County, Pecos County, Terrell County, Texas

The Storm Prediction Center issued this mesoscale discussion at May 31, 2021, 5:49 PM CDT for Brewster County, Pecos County, Terrell County, Texas. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: May 31, 2021, 5:49 PM CDT (22:49 UTC)
Expired: May 31, 2021, 7:45 PM CDT
In force: 116 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 229

Counties Brewster County, TX, Pecos County, TX, Terrell County, TX

The radar

The Midland/Odessa radar (KMAF), 195 km from the middle of the area, began a volume at 22:49 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, 10.8 hours before the alert went out and 195 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: 1949 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 516 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 149 m²/s²
0-3 km storm-relative helicity: 119 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 7.1

Open this sounding in Storm Lab

The text

As transmitted.

699 
ACUS11 KWNS 312249
SWOMCD
SPC MCD 312249 
TXZ000-010045-

Mesoscale Discussion 0829
NWS Storm Prediction Center Norman OK
0549 PM CDT Mon May 31 2021

Areas affected...Parts of southwestern Texas

Concerning...Severe Thunderstorm Watch 229...

Valid 312249Z - 010045Z

The severe weather threat for Severe Thunderstorm Watch 229
continues.

SUMMARY...Discrete supercells may continue to develop across the
Davis and Glass Mountains vicinity into early evening, perhaps
gradually beginning to consolidate into cluster while approaching
the Del Rio, TX vicinity through 7-9 PM CDT.  Trends are being
monitored for the possibility of an additional severe weather watch
southeast of Severe Thunderstorm Watch 229.

DISCUSSION...Relatively moist easterly/northeasterly near-surface
flow (associated with convective outflow/rain-cooled air) into the
northeastern slopes of the Davis and Glass Mountains, is
contributing to a corridor of strong boundary-layer instability
across the higher terrain.  This is where lower/mid tropospheric
lapse rates remain steepest, aided by strongest heating and
boundary-layer mixing, and orographic forcing is contributing to
continuing thunderstorm initiation.

It appears that a 40 kt mid-level jet (around 500 mb), within
otherwise rather modest west-southwesterly deep-layer ambient mean
flow, is contributing to strong vertical shear, and this will
continue to support discrete supercell development into early
evening.  Given these profiles,  propagation will remain slow and to
the southeast.  This will take storms both into northern Coahuila
and along the outflow boundary near the Rio Grande River, into areas
near/northwest of Del Rio, TX through 00-02Z.  It is possible that
storms and associated outflows might begin to consolidate into an
upscale growing and organizing cluster.

..Kerr.. 05/31/2021

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

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

LAT...LON   31050277 30260190 29630096 29110258 29870338 30440403
            30840427 31050277

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 30, 8:59 PM CDT	Mesoscale Discussion	SPC	Carson, Gray, Hansford, Hemphill, Hutchinson, Lipscomb and 6 more	91 min
May 30, 9:17 PM CDT	Severe Thunderstorm Watch	SPC	Armstrong, Carson, Collingsworth, Donley, Gray, Hemphill and 4 more	5 hr
May 30, 9:22 PM CDT	Mesoscale Discussion	SPC	Andrews, Borden, Cochran, Cottle, Crosby, Dawson and 20 more	83 min
May 30, 11:43 PM CDT	Mesoscale Discussion	SPC	Bailey, Cochran, Cottle, Crosby, Dickens, Floyd and 12 more	92 min
May 31, 2:12 AM CDT	Mesoscale Discussion	SPC	Borden, Fisher, Haskell, Howard, Jones, Kent and 5 more	3 hr
May 31, 11:33 AM CDT	Mesoscale Discussion	SPC	Andrews, Borden, Brewster, Cochran, Crane, Crockett and 26 more	87 min
May 31, 12:16 PM CDT	Severe Thunderstorm Watch	SPC	Andrews, Coke, Crane, Crockett, Culberson, Ector and 21 more	9 hr
May 31, 2:15 PM CDT	Mesoscale Discussion	SPC	Bosque, Brown, Callahan, Coleman, Comanche, Coryell and 10 more	2 hr
May 31, 2:54 PM CDT	Severe Thunderstorm Watch	SPC	Bell, Bosque, Comanche, Coryell, Ellis, Erath and 13 more	4 hr
May 31, 3:29 PM CDT	Mesoscale Discussion	SPC	Andrews, Coke, Crane, Crockett, Culberson, Ector and 21 more	91 min
May 31, 5:12 PM CDT	Mesoscale Discussion	SPC	Bell, Bosque, Coryell, Ellis, Falls, Freestone and 10 more	93 min

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.