Alert archive / Texas / Tornado Watches in 2002

Tornado Watch 797

December 23, 200243 counties in Texas

The Storm Prediction Center issued this tornado watch at Dec 23, 2002, 5:00 AM CST for 43 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Dec 23, 2002, 5:00 AM CST (11:00 UTC)
Expired: Dec 23, 2002, 10:00 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

All 43 counties

Atascosa County, TX, Austin County, TX, Bastrop County, TX, Bee County, TX, Bexar County, TX, Brazos County, TX, Burleson County, TX, Caldwell County, TX, Calhoun County, TX, Colorado County, TX, Comal County, TX, DeWitt County, TX, Duval County, TX, Fayette County, TX, Fort Bend County, TX, Goliad County, TX, Gonzales County, TX, Grimes County, TX, Guadalupe County, TX, Hays County, TX, Jackson County, TX, Jim Wells County, TX, Karnes County, TX, Kendall County, TX, Lavaca County, TX, Lee County, TX, Leon County, TX, Live Oak County, TX, Madison County, TX, Matagorda County, TX, McMullen County, TX, Milam County, TX, Montgomery County, TX, Refugio County, TX, Robertson County, TX, San Patricio County, TX, Travis County, TX, Victoria County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wharton County, TX, Wilson County, TX

The radar

The Austin/San Antonio radar (KEWX), 52 km from the middle of the area, began a volume at 11:00 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.

Warnings issued inside it

9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Dec 23, 6:07 AM CST	Tornado Warning	EWX	Hays, Travis	53 min
Dec 23, 7:00 AM CST	Tornado Warning	EWX	Travis, Williamson	30 min
Dec 23, 7:43 AM CST	Tornado Warning	EWX	DeWitt	47 min
Dec 23, 8:08 AM CST	Severe Thunderstorm Warning	EWX	Fayette, Lavaca	52 min
Dec 23, 8:58 AM CST	Severe Thunderstorm Warning	EWX	Fayette	47 min
Dec 23, 9:03 AM CST	Severe Thunderstorm Warning	EWX	Lee	27 min
Dec 23, 9:16 AM CST	Tornado Warning	EWX	Fayette	29 min
Dec 23, 9:41 AM CST	Tornado Warning	HGX	Brazos	49 min
Dec 23, 9:57 AM CST	Tornado Warning	HGX	Austin	33 min

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 00:00Z, 11.0 hours before the alert went out and 205 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: 917 J/kg
Mixed-layer CIN: -28 J/kg
Mixed-layer LCL: 589 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 209 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 3.7

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 231100
SEL7  
SPC WW 231100
TXZ000-CWZ000-231600-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 797
STORM PREDICTION CENTER NORMAN OK
500 AM CST MON DEC 23 2002

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   CENTRAL AND SOUTHEAST TEXAS                              
   AND ADJACENT COASTAL WATERS                     

EFFECTIVE THIS MONDAY MORNING FROM 500 AM UNTIL 1000 AM CST.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 95 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 65 MILES SOUTH SOUTHWEST OF SAN ANTONIO TEXAS
TO 60 MILES EAST SOUTHEAST OF COLLEGE STATION TEXAS.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

DISCUSSION...CURRENT SATELLITE IMAGERY AND SURFACE DATA SUGGEST
UPPER TROUGH AND ASSOCIATED SURFACE LOW OVER THE BIG BEND REGION
WILL TRACK EASTWARD ACROSS CENTRAL TX THIS MORNING.  SCATTERED
SHOWERS/THUNDERSTORMS HAVE BEEN DEVELOPING AHEAD OF SYSTEM...AND
SHOULD CONTINUE TO DO SO THROUGH MID MORNING.  RICH LOW LEVEL
MOISTURE AND STRONG VERTICAL SHEAR PROFILES SUGGEST THE POTENTIAL
FOR ISOLATED SEVERE STORMS AND POSSIBLE TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. 
MEAN STORM MOTION VECTOR 23035.

...HART

300,0985 313,0952 285,0952 271,0985

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 23, 9:45 AM CST	Tornado Watch	SPC	Angelina, Austin, Bastrop, Brazoria, Brazos, Burleson and 29 more	5 hr
Dec 23, 2:10 PM CST	Tornado Watch	SPC	Angelina, Austin, Bastrop, Brazos, Burleson, Chambers and 31 more	6 hr
Dec 23, 3:35 PM CST	Severe Thunderstorm Watch	SPC	Atascosa, Bandera, Bastrop, Bee, Bexar, Caldwell and 22 more	4 hr

Nearby

Tornado Watches in Texas, 2002 Every tornado watch in 2002

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.