Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 389

April 15, 202118 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2021, 12:24 PM CDT for 18 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 15, 2021, 12:24 PM CDT (17:24 UTC)
Expired: Apr 15, 2021, 2:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 96

Counties Bastrop County, TX, Bell County, TX, Blanco County, TX, Burnet County, TX, Coryell County, TX, Falls County, TX, Gillespie County, TX, Lampasas County, TX, Lee County, TX, Llano County, TX, Mason County, TX, McCulloch County, TX, McLennan County, TX, Milam County, TX, Mills County, TX, San Saba County, TX, Travis County, TX, Williamson County, TX

The radar

The Ft Hood radar (KGRK), 103 km from the middle of the area, began a volume at 17:25 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 12:00Z, 5.4 hours before the alert went out and 246 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 629 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

872 
ACUS11 KWNS 151725
SWOMCD
SPC MCD 151724 
TXZ000-151930-

Mesoscale Discussion 0389
NWS Storm Prediction Center Norman OK
1224 PM CDT Thu Apr 15 2021

Areas affected...portions of central Texas

Concerning...Severe Thunderstorm Watch 96...

Valid 151724Z - 151930Z

The severe weather threat for Severe Thunderstorm Watch 96
continues.

SUMMARY...Local risk for large hail continues.

DISCUSSION...Latest radar loop shows isolated strong/severe storms
continuing across parts of central Texas, on the southern fringe of
an expanding area of convection across portions of western and
northern Texas and into southwestern Oklahoma.  While instability
diminishes with northward extent -- and thus severe risk does, as
well -- ample instability over central Texas in tandem with
moderately strong shear through the cloud-bearing layer will
continue to support risk for large hail locally, with
elevated/rotating storms.

With time, several CAMs suggest that storms will continue moving
eastward/northeastward out of the existing watch.  While storms
moving northeastward appear to be of less concern, greater CAPE east
of the existing watch could permit an increase in local hail risk
into the Hill Country and vicinity.  However, it appears at this
time that risk would likely remain very isolated, casting
uncertainty on the need for a possible/downstream WW.

..Goss.. 04/15/2021

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

ATTN...WFO...HGX...FWD...EWX...SJT...

LAT...LON   30489964 30819982 31499963 31689858 31539671 30949660
            30089693 30149849 30489964

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 15, 8:17 AM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bexar, Blanco, Comal, Edwards and 13 more	2 hr
Apr 15, 8:36 AM CDT	Severe Thunderstorm Watch	SPC	Bandera, Blanco, Burnet, Concho, Crockett, Edwards and 19 more	8 hr
Apr 15, 10:56 AM CDT	Mesoscale Discussion	SPC	Bandera, Concho, Edwards, Gillespie, Kerr, Kimble and 9 more	94 min
Apr 15, 4:55 PM CDT	Mesoscale Discussion	SPC	Austin, Brazoria, Burleson, Fort Bend, Harris, Lee and 4 more	3 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.