Alert archive / Texas / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 31, NWS Austin/San Antonio, TX

April 12, 2021Llano County, Texas

NWS Austin/San Antonio, TX issued this severe thunderstorm warning at Apr 12, 2021, 6:30 PM CDT for Llano County, Texas. It was in force for 60 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Apr 12, 2021, 6:30 PM CDT (23:30 UTC)
Expired
Apr 12, 2021, 7:30 PM CDT
In force
60 min
Issued by
NWS Austin/San Antonio, TX
Area
Storm-based polygon
Hail
1.25 in
Wind
60.0 mph

County Llano County, TX

The radar

The Ft Hood radar (KGRK), 138 km from the middle of the area, began a volume at 23:30 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.

What was reported inside it

TimeReportWhereRemark
Apr 12, 7:05 PM CDTHAIL 1.757 W Valley Spring, TXGOLFBALL SIZE HAIL 4 MILES SOUTHEAST OF PONTOTOC ON COUNTY ROAD 405. 3 INCHES OF HAIL ACCUMULATION ON THE GROUND.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 12, 3:51 PM CDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Del Rio, TX (KDRT), launched 12:00Z, 11.5 hours before the alert went out and 254 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-pSkew-T log-p diagram, Del Rio, TX at 12:00Z on 2021-04-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 876 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Del Rio, TX at 12:00Z on 2021-04-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 139 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
876 J/kg
Mixed-layer CIN
-408 J/kg
Mixed-layer LCL
922 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
139 m²/s²
0-3 km storm-relative helicity
124 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

561 
WUUS54 KEWX 122330
SVREWX
TXC299-130030-
/O.NEW.KEWX.SV.W.0031.210412T2330Z-210413T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Austin/San Antonio TX
630 PM CDT Mon Apr 12 2021

The National Weather Service in Austin San Antonio has issued a

* Severe Thunderstorm Warning for...
  Northwestern Llano County in south central Texas...

* Until 730 PM CDT.

* At 629 PM CDT, a severe thunderstorm was located near Art, or 9
  miles northeast of Mason, moving northeast at 15 mph.

  HAZARD...60 mph wind gusts and half dollar size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Valley Spring and Field Creek. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3080 9870 3078 9896 3092 9896 3092 9877
TIME...MOT...LOC 2329Z 240DEG 13KT 3083 9911 

HAIL...1.25IN
WIND...60MPH
 
$$

YB
1 follow-up statement
556 
WWUS54 KEWX 130003
SVSEWX

Severe Weather Statement
National Weather Service Austin/San Antonio TX
703 PM CDT Mon Apr 12 2021

TXC299-130030-
/O.CON.KEWX.SV.W.0031.000000T0000Z-210413T0030Z/
Llano TX-
703 PM CDT Mon Apr 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR NORTHWESTERN LLANO COUNTY...

At 703 PM CDT, a severe thunderstorm was located over Pontotoc, or 17
miles northeast of Mason, moving northeast at 15 mph.

This is a very dangerous storm.

HAZARD...Baseball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be severely injured. 
         Expect shattered windows, extensive damage to roofs, 
         siding, and vehicles.

Locations impacted include...
Valley Spring and Field Creek. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

This storm is producing large hail. SEEK SHELTER NOW inside a sturdy
structure and stay away from windows.

&&

LAT...LON 3080 9870 3078 9896 3092 9896 3092 9877
TIME...MOT...LOC 0003Z 240DEG 13KT 3089 9899 

HAIL...2.75IN
WIND...60MPH
 
$$

YB

Nearby

Severe Thunderstorm Warnings in Texas, 2021Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.