Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 507

May 3, 202114 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 6:19 PM CDT for 14 counties in Texas. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: May 3, 2021, 6:19 PM CDT (23:19 UTC)
Expired: May 3, 2021, 8:15 PM CDT
In force: 116 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...severe thunderstorm watch likely
Chance of a watch: 80%

Counties Callahan County, TX, Eastland County, TX, Fisher County, TX, Haskell County, TX, Jack County, TX, Jones County, TX, Nolan County, TX, Palo Pinto County, TX, Shackelford County, TX, Stephens County, TX, Stonewall County, TX, Taylor County, TX, Throckmorton County, TX, Young County, TX

The radar

The Dyess AFB radar (KDYX), 21 km from the middle of the area, began a volume at 23:18 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 134May 3, 6:35 PM CDT

The nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 11.3 hours before the alert went out and 205 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: 1296 J/kg
Mixed-layer CIN: -475 J/kg
Mixed-layer LCL: 1712 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 480 m²/s²
0-3 km storm-relative helicity: 456 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

630 
ACUS11 KWNS 032319
SWOMCD
SPC MCD 032319 
TXZ000-040115-

Mesoscale Discussion 0507
NWS Storm Prediction Center Norman OK
0619 PM CDT Mon May 03 2021

Areas affected...Portions of northwest into central TX

Concerning...Severe potential...Severe Thunderstorm Watch likely 

Valid 032319Z - 040115Z

Probability of Watch Issuance...80 percent

SUMMARY...A large hail threat will likely continue this evening as
storms move eastward. Severe Thunderstorm Watch issuance is likely.

DISCUSSION...Multiple severe supercells across west TX are expected
to move eastward this evening into parts of northwest/central TX.
This activity will remain to the north of a surface front, but
surface dewpoints remain in the upper 50s to low 60s behind the
front. 45-50 kt of deep-layer shear will likely continue to support
supercell structures, and the presence of steepened mid-level lapse
rates and MUCAPE of 1500-2000 J/kg suggest large hail should remain
the primary severe concern. Very large hail to 2+ inches in diameter
also appears possible given the favorable thermodynamic and
kinematic environment, as well as the robust structure of the
ongoing supercells. Even with the frontal passage, isolated damaging
winds may also occur since low-level lapse rates remain steep with
clouds clearing and diurnal heating that has occurred earlier this
afternoon. Given the expectation for multiple supercells to move
eastward this evening and pose a continued large to perhaps very
large hail threat, a Severe Thunderstorm Watch will likely be
needed.

..Gleason/Thompson.. 05/03/2021

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

ATTN...WFO...FWD...SJT...LUB...

LAT...LON   32120060 33380043 33399800 32609818 32099897 32120060

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 3, 12:44 PM CDT	Mesoscale Discussion	SPC	Dallam, Deaf Smith, Hartley, Moore, Oldham	2 hr
May 3, 2:24 PM CDT	Mesoscale Discussion	SPC	Andrews, Borden, Cochran, Dawson, Fisher, Gaines and 12 more	2 hr
May 3, 3:14 PM CDT	Mesoscale Discussion	SPC	Bosque, Collin, Comanche, Cooke, Dallas, Delta and 24 more	2 hr
May 3, 3:15 PM CDT	Severe Thunderstorm Watch	SPC	Andrews, Borden, Cochran, Crosby, Dawson, Gaines and 12 more	6 hr
May 3, 3:48 PM CDT	Tornado Watch	SPC	Bell, Bosque, Collin, Comanche, Cooke, Coryell and 27 more	7 hr
May 3, 5:12 PM CDT	Mesoscale Discussion	SPC	Borden, Cochran, Dawson, Gaines, Garza, Lynn and 3 more	93 min
May 3, 5:55 PM CDT	Mesoscale Discussion	SPC	Bosque, Cooke, Denton, Grayson, Johnson, Somervell and 1 more	95 min
May 3, 5:56 PM CDT	Mesoscale Discussion	SPC	Frio, La Salle, Medina	94 min
May 3, 6:36 PM CDT	Severe Thunderstorm Watch	SPC	Callahan, Eastland, Fisher, Haskell, Jack, Jones and 8 more	5 hr

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.