Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 1254

July 11, 202112 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Jul 11, 2021, 2:46 AM CDT for 12 counties in Texas. It was in force for 29 min.

The area

The outline as issued.

The facts

Issued: Jul 11, 2021, 2:46 AM CDT (07:46 UTC)
Expired: Jul 11, 2021, 3:15 AM CDT
In force: 29 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 370

Counties Archer County, TX, Baylor County, TX, Clay County, TX, Collin County, TX, Denton County, TX, Foard County, TX, Grayson County, TX, Hardeman County, TX, Jack County, TX, Knox County, TX, Wilbarger County, TX, Wise County, TX

The radar

The Altus AFB radar (KFDR), 103 km from the middle of the area, began a volume at 07:46 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

Fort Worth, TX (KFWD), launched 00:00Z, 7.8 hours before the alert went out and 128 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: 1457 J/kg
Mixed-layer CIN: -26 J/kg
Mixed-layer LCL: 1695 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -51 m²/s²
0-3 km storm-relative helicity: -26 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

As transmitted.

842 
ACUS11 KWNS 110746
SWOMCD
SPC MCD 110746 
OKZ000-TXZ000-110815-

Mesoscale Discussion 1254
NWS Storm Prediction Center Norman OK
0246 AM CDT Sun Jul 11 2021

Areas affected...western North Texas

Concerning...Severe Thunderstorm Watch 370...

Valid 110746Z - 110815Z

The severe weather threat for Severe Thunderstorm Watch 370
continues.

SUMMARY...Overall severe threat has lessened, with this trend
expected to gradually continue as storms spread southward. 
Additional WW issuance south of the ongoing activity is not
anticipated, but local extension may be needed for an hour or so
across southwestern portions of WW 370.

DISCUSSION...Latest radar loop shows a continuous band of storms
moving southward, from western North Texas eastward across the Red
River Valley area to southern Arkansas.  Storm intensity overall has
gradually diminished, though a few severe-caliber gusts are still
occurring locally, on occasion, with stronger storms embedded within
the line.

With the greatest surge in the line now occurring across the western
North Texas portion of the watch,  but with a more stable airmass
downstream across this region, expect threat to gradually diminish
as storms advance.  Overall, while a few additional strong/possibly
damaging gusts may occur over the next 1 to 2 hours, risk should
remain local/isolated enough not to warrant new WW issuance south of
the exist portions of WW 370.

..Goss.. 07/11/2021

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

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

LAT...LON   34470029 33929856 33559732 33919613 33449628 33019654
            33129835 33399999 34470029

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 10, 9:21 PM CDT	Mesoscale Discussion	SPC	Clay, Wichita	84 min
Jul 10, 9:35 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Clay, Cooke, Foard, Grayson and 5 more	5 hr
Jul 10, 11:56 PM CDT	Mesoscale Discussion	SPC	Clay, Cooke, Grayson, Hardeman, Montague, Wichita and 1 more	94 min
Jul 11, 11:48 AM CDT	Mesoscale Discussion	SPC	Culberson, Loving, Reeves, Ward, Winkler, Yoakum	87 min
Jul 11, 12:16 PM CDT	Severe Thunderstorm Watch	SPC	Andrews, Borden, Cochran, Dawson, Ector, Gaines and 14 more	7 hr
Jul 11, 2:33 PM CDT	Mesoscale Discussion	SPC	Andrews, Cochran, Dawson, Ector, Gaines, Hockley and 5 more	87 min
Jul 11, 3:23 PM CDT	Severe Thunderstorm Watch	SPC	El Paso, Hudspeth	8 hr
Jul 11, 6:51 PM CDT	Mesoscale Discussion	SPC	Anderson, Bell, Cherokee, Coke, Concho, Coryell and 22 more	84 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.