Alert archive / Texas / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 72, NWS Austin/San Antonio, TX

May 20, 2011Caldwell County, Hays County, Travis County, Texas

NWS Austin/San Antonio, TX issued this severe thunderstorm warning at May 20, 2011, 8:27 PM CDT for Caldwell County, Hays County, Travis County, Texas. It was in force for 23 min. 3 reports 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: May 20, 2011, 8:27 PM CDT (01:27 UTC)
Expired: May 20, 2011, 8:50 PM CDT
In force: 23 min
Issued by: NWS Austin/San Antonio, TX
Area: Storm-based polygon

Counties Caldwell County, TX, Hays County, TX, Travis County, TX

The radar

The Austin/San Antonio radar (KEWX), 54 km from the middle of the area, began a volume at 01:28 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

Time	Report	Where	Remark
May 20, 8:32 PM CDT	HAIL 1	2 Se Driftwood, TX	PEA TO QUARTER SIZE HAIL ALONG WITH AN INCH OF RAINFALL IN LESS THAN AN HOUR.
May 20, 8:40 PM CDT	HAIL 0.25	Tanglewood Forest, TX
May 20, 8:50 PM CDT	HAIL 0.88	7 Ne Wimberley, TX	NICKEL SIZE HAIL

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.

Issued	Product	Office	Lasted
May 20, 12:28 PM CDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 00:00Z, 1.5 hours before the alert went out and 273 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: 4855 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 870 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 59 m²/s²
0-3 km storm-relative helicity: 41 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 9.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

233 
WUUS54 KEWX 210127
SVREWX
TXC055-209-453-210215-
/O.NEW.KEWX.SV.W.0072.110521T0127Z-110521T0215Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
827 PM CDT FRI MAY 20 2011

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME NORTH CENTRAL CALDWELL COUNTY...
  CENTRAL HAYS COUNTY...
  SOUTH CENTRAL TRAVIS COUNTY...

* UNTIL 915 PM CDT.

* AT 823 PM CDT...NWS METEOROLOGISTS HAVE DETECTED A SEVERE
  THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL.  THIS STORM
  WAS LOCATED NEAR DRIFTWOOD...OR 8 MILES WEST OF TANGLEWOOD
  FOREST...AND MOVING EAST AT 15 MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE BUDA...ONION CREEK...AUSTIN
  BERGSTROM INT AP AND MUSTANG RIDGE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

&&

LAT...LON 3025 9766 3001 9765 3004 9805 3019 9805
TIME...MOT...LOC 0127Z 262DEG 14KT 3015 9795

$$

1 follow-up statement

292 
WWUS54 KEWX 210150
SVSEWX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
850 PM CDT FRI MAY 20 2011

TXC055-209-453-210200-
/O.CAN.KEWX.SV.W.0072.000000T0000Z-110521T0215Z/
TRAVIS TX-HAYS TX-CALDWELL TX-
850 PM CDT FRI MAY 20 2011

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME NORTH CENTRAL
CALDWELL...CENTRAL HAYS AND SOUTH CENTRAL TRAVIS COUNTIES IS
CANCELLED...

LAT...LON 3025 9766 3001 9765 3004 9805 3019 9805
TIME...MOT...LOC 0150Z 262DEG 14KT 3016 9785

$$

The office that day

Everything else NWS Austin/San Antonio, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 7:49 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Hays, Travis, Williamson	41 min
May 20, 8:04 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Caldwell, Hays, Travis	26 min
May 20, 8:58 PM CDT	Severe Thunderstorm Warning	EWX	Hays, Travis	32 min
May 20, 8:59 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Lee, Travis, Williamson	61 min
May 20, 9:22 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Caldwell, Lee, Travis	38 min
May 20, 10:02 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Caldwell	43 min
May 20, 10:32 PM CDT	Severe Thunderstorm Warning	EWX	Caldwell, Guadalupe, Hays	43 min
May 21, 4:58 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Llano, Williamson	47 min
May 21, 5:44 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Williamson	46 min
May 21, 6:00 PM CDT	Areal Flood Advisory	EWX	Burnet, Llano	2 hr
May 21, 6:00 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Llano	45 min
May 21, 6:29 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Williamson	46 min
May 21, 6:52 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Williamson	38 min
May 21, 6:59 PM CDT	Tornado Warning	EWX	Burnet	31 min

Nearby

Severe Thunderstorm Warnings in Texas, 2011 Every severe thunderstorm warning in 2011

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.