Alert archive / Texas / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 86, NWS Austin/San Antonio, TX

May 21, 2011Williamson County, Texas

NWS Austin/San Antonio, TX issued this severe thunderstorm warning at May 21, 2011, 8:27 PM CDT for Williamson County, Texas. It was in force for 48 min. 4 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 21, 2011, 8:27 PM CDT (01:27 UTC)
Expired: May 21, 2011, 9:15 PM CDT
In force: 48 min
Issued by: NWS Austin/San Antonio, TX
Area: Storm-based polygon

County Williamson County, TX

The radar

The Ft Hood radar (KGRK), 33 km from the middle of the area, began a volume at 01:29 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 21, 8:53 PM CDT	FUNNEL CLOUD	4 Ssw Florence, TX	FLORENCE FIRE DEPARTMENT OBSERVED FUNNEL CLOUD.
May 21, 8:57 PM CDT	TSTM WND DMG	Andice, TX	MINOR MOBILE HOME DAMAGE IN AND AROUND ANDICE AS WELL AS SOME FENCES BLOWN DOWN.
May 21, 9:00 PM CDT	TORNADO	1 Sse Andice, TX	NWS DAMAGE SURVEY CONFIRMS A TORNADO TOUCHED DOWN ABOUT 1 MILE SOUTHEAST OF ANDICE. THE TORNADO TRACKED APPROXIMATELY 1.5 MILES TO THE NORTHEAST. DAMAGE CONSISTED OF MAINLY TREE DAMAGE...DAMAGE TO CARPORTS...MOBILE HOME ROOFS...DECKS...AND OUTDOOR EQUIPMENT. I
May 21, 9:04 PM CDT	FUNNEL CLOUD	Andice, TX	ROTATING WALL CLOUD OVER THE CITY OF ANDICE.

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 21, 1:45 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Fort Worth, TX (KFWD), launched 00:00Z, 1.5 hours before the alert went out and 231 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: 3908 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 978 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 116 m²/s²
0-3 km storm-relative helicity: 188 m²/s²
Significant tornado parameter: 3.2
Supercell composite: 16.6

Open this sounding in Storm Lab

The text

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

239 
WUUS54 KEWX 220127
SVREWX
TXC491-220215-
/O.NEW.KEWX.SV.W.0086.110522T0127Z-110522T0215Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
827 PM CDT SAT MAY 21 2011

THE NATIONAL WEATHER SERVICE IN AUSTIN SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTH CENTRAL WILLIAMSON COUNTY...

* UNTIL 915 PM CDT.

* AT 820 PM CDT...NWS METEOROLOGISTS HAVE DETECTED A SEVERE
  THUNDERSTORM.  THIS STORM WAS LOCATED NEAR ANDICE...OR 9 MILES
  NORTHWEST OF SERENADA...AND MOVING EAST AT 15 MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE GEORGETOWN DAM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM CDT
SATURDAY EVENING FOR SOUTH CENTRAL TEXAS.

&&

LAT...LON 3085 9760 3064 9764 3070 9790 3088 9785
TIME...MOT...LOC 0127Z 281DEG 14KT 3078 9778

$$

1 follow-up statement

840 
WWUS54 KEWX 220208
SVSEWX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
908 PM CDT SAT MAY 21 2011

TXC491-220215-
/O.CON.KEWX.SV.W.0086.000000T0000Z-110522T0215Z/
WILLIAMSON TX-
908 PM CDT SAT MAY 21 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 915 PM CDT
FOR NORTH CENTRAL WILLIAMSON COUNTY...

AT 901 PM CDT...NWS METEOROLOGISTS CONTINUED TO DETECT A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING BASEBALL SIZE HAIL...AND DAMAGING
WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR FLORENCE...OR
8 MILES NORTHWEST OF SERENADA...MOVING EAST AT 15 MPH.

THE SEVERE THUNDERSTORM WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS
OF THE INDICATED COUNTY.

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 3071 9765 3070 9785 3088 9785 3085 9762
TIME...MOT...LOC 0208Z 267DEG 12KT 3079 9775

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
May 21, 7:10 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Travis, Williamson	50 min
May 21, 7:27 PM CDT	Tornado Warning	EWX	Burnet, Williamson	33 min
May 21, 7:44 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Williamson	46 min
May 21, 7:50 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Llano	40 min
May 21, 7:59 PM CDT	Tornado Warning	EWX	Burnet, Williamson	31 min
May 21, 8:08 PM CDT	Areal Flood Advisory	EWX	Burnet, Williamson	112 min
May 21, 8:11 PM CDT	Tornado Warning	EWX	Burnet, Llano	34 min
May 21, 8:27 PM CDT	Tornado Warning	EWX	Williamson	33 min
May 21, 8:32 PM CDT	Severe Thunderstorm Warning	EWX	Burnet	43 min
May 21, 8:44 PM CDT	Tornado Warning	EWX	Burnet	31 min
May 21, 8:59 PM CDT	Tornado Warning	EWX	Williamson	31 min
May 21, 9:14 PM CDT	Severe Thunderstorm Warning	EWX	Burnet, Williamson	46 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.