Alert archive / Texas / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 74, NWS Austin/San Antonio, TX

May 20, 2001Llano County, Texas

NWS Austin/San Antonio, TX issued this severe thunderstorm warning at May 20, 2001, 7:09 PM CDT for Llano County, Texas. It was in force for 66 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: May 20, 2001, 7:09 PM CDT (00:09 UTC)
Expired: May 20, 2001, 8:15 PM CDT
In force: 66 min
Issued by: NWS Austin/San Antonio, TX
Area: Whole counties

County Llano County, TX

What was reported inside it

Time	Report	Where	Remark
May 20, 8:10 PM CDT	Thunderstorm Wind	Bluffton, TX	Severe thunderstorm winds caused widespread damage to trees, roofs from Llano eastward.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Del Rio, TX (KDRT), launched 00:00Z, 0.2 hours before the alert went out and 255 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: 757 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 2899 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.3

Open this sounding in Storm Lab

The text

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

000 
WUUS54 KEWX 210013
SVRSAT
TXC299-210115-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
709 PM CDT SUN MAY 20 2001

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR THE FOLLOWING COUNTIES IN TEXAS...
  LLANO

* UNTIL 815 PM CDT

* AT 709 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 28 MILES WEST OF LLANO...OR ABOUT 10 MILES     
  SOUTHEAST OF MASON.  THE STORM WAS MOVING TOWARD THE EAST AT 20    
  MPH.  LARGE HAIL...GUSTY DAMAGING WINDS AND FREQUENT DEADLY        
  LIGHTNING ARE INDICATED IN THIS STORM.

* THE SEVERE THUNDERSTORM WILL BE...
  IN THE CASTELL AREA AT 720 PM
  IN THE LLANO-VALLEY SPRING AREA AT 740 PM
  IN THE LAKE BUCHANAN AREA BEFORE 8 PM

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Austin/San Antonio, TX wrote its last area forecast discussion before this severe thunderstorm warning went out at May 20, 2:15 PM CDT, 4 hours 54 minutes earlier.

Area forecast discussion, May 20, 2:15 PM CDT, 4 hours 54 minutes before

SOUTH CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
215 PM CDT SUN MAY 20 2001

AFTER A BRIEF STINT WITH SHOWERS AND THUNDERSTORMS TOMORROW...A COLD
FRONT WILL USHER IN COOLER AND MUCH DRIER AIR...WITH THE GULF OF
MEXICO FLOW BEING SHUT OFF FOR MOST OF THE WEEK.  THE EXTENDED HAS A
GOOD RETURN FLOW OF MOISTURE BY NEXT SUNDAY.

WE ARE POTENTIALLY VERY UNSTABLE ALOFT WITH THE LATEST GOES CAPE
INDEX SHOWING CAPES OF 3000-5000.  HOWEVER...WE ARE JUST NOW
CLEARING ACROSS THE EASTERN PORTIONS OF SOUTH CENTRAL TEXAS AND
VISUAL CLUES OF GOOD SUBSIDENCE OCCURRING (VISIBILITIES LOWERING IN
HAZE). WITH LITTLE IN WAY OF FOCUS OR POSITIVE DYNAMICS ALOFT...
WILL ONLY PLACE ISOLATED SHOWERS OR THUNDERSTORMS WEST TONIGHT...
WHERE DRY LINE SET UP WILL BE.

MODELS HAVE BEEN VERY CONSISTENT IN BRINGING IN A GOOD COLD FRONT
AROUND MIDDAY MONDAY...AND THIS CONTINUES THE CASE.  A BRIEF SHOT AT
SOME SHOWERS AND THUNDERSTORMS ALONG THE FRONT WITH GOOD LOW LEVEL
FORCING. THE TIME OF DAY PRECLUDES US FROM GOING ANY HIGHER THAN 30
PERCENT AT PRESENT.  SOME CYCLOGENESIS ALONG THE COASTLINE MONDAY
NIGHT WILL FORCE US TO CONTINUE WITH LOW POPS (MOSTLY LIGHT RAIN OR
SHOWERS) OVER THE SOUTH CENTRAL AND SOUTHEAST ZONES TOMORROW NIGHT.

MASSIVE VORTEX DEVELOPING ACROSS UPPER MIDWEST INTO THE NORTHEAST
U.S. BY MIDWEEK KEEPS AREA DRY AND A LITTLE COOLER THAN NORMAL.
SECONDARY WAVE PUSHES IN LATE THURSDAY WITH A FEW MORE CLOUDS AND A
REINFORCEMENT OF COOL AIR.   SOUTHERLY FLOW FINALLY RETURNS WITH A
VENGEANCE SUNDAY AS THE HIGH MOVES OFF INTO THE ATLANTIC WHILE A
LONGWAVE TROUGH PATTERN SETS UP OVER THE WESTERN U.S.

PRELIMINARY NUMBERS...
AUS 072/080/051/081 0310
DRT 068/089/057/085 1200
SAT 074/083/053/081 0320

.EWX...NONE.

02/19

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 7:10 PM CDT	Severe Thunderstorm Warning	EWX	Caldwell	65 min
May 20, 7:28 PM CDT	Severe Thunderstorm Warning	EWX	Karnes, Wilson	62 min
May 20, 7:51 PM CDT	Severe Thunderstorm Warning	EWX	Burnet	69 min
May 20, 8:29 PM CDT	Tornado Warning	EWX	Burnet	31 min
May 20, 8:45 PM CDT	Tornado Warning	EWX	Travis, Williamson	60 min
May 20, 9:47 PM CDT	Severe Thunderstorm Warning	EWX	Bastrop, Lee, Travis, Williamson	43 min
May 21, 6:39 AM CDT	Flash Flood Warning	EWX	Guadalupe	2 hr

Nearby

Severe Thunderstorm Warnings in Texas, 2001 Every severe thunderstorm warning in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.