Alert archive / Texas / Tornado Watches in 2002

Tornado Watch 811

December 30, 200215 counties in Texas

The Storm Prediction Center issued this tornado watch at Dec 30, 2002, 2:50 PM CST for 15 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Dec 30, 2002, 2:50 PM CST (20:50 UTC)
Expired: Dec 30, 2002, 9:00 PM CST
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Aransas County, TX, Bee County, TX, Calhoun County, TX, Duval County, TX, Goliad County, TX, Jim Wells County, TX, Kleberg County, TX, La Salle County, TX, Live Oak County, TX, McMullen County, TX, Nueces County, TX, Refugio County, TX, San Patricio County, TX, Victoria County, TX, Webb County, TX

The radar

The Corpus Christi radar (KCRP), 106 km from the middle of the area, began a volume at 20:52 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.

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 12:00Z, 8.8 hours before the alert went out and 123 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: 302 J/kg
Mixed-layer CIN: -271 J/kg
Mixed-layer LCL: 652 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

735 
WWUS20 KWNS 302055
SEL1  
SPC WW 302050
TXZ000-CWZ000-310300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 811
STORM PREDICTION CENTER NORMAN OK
250 PM CST MON DEC 30 2002

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

   SOUTHERN TEXAS                              
   COASTAL WATERS                     

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 250 PM UNTIL 900
PM CST.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 90 STATUTE MILES EAST AND WEST
OF A LINE FROM 45 MILES SOUTHWEST OF ALICE TEXAS TO 35 MILES NORTH
NORTHWEST OF BEEVILLE 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.

OTHER WATCH INFORMATION...  CONTINUE...WW 808...WW 809...WW 810...

DISCUSSION...COMBINATION OF TEMPERATURES APPROACHING 80F AND RAPID
COOLING ALOFT/UVV WILL SUPPORT CONTINUED WEAKENING OF STRONG CAP
OVER THIS REGION.  ISOLATED SUPERCELLS ARE EXPECTED TO DEVELOP NEAR
THE RIO GRANDE AND TRACK ENEWD THROUGH THE EVENING.   VERY LARGE
HAIL ALONG WITH THE THREAT OF TORNADOES AND DAMAGING WINDS WILL
LIKELY ACCOMPANY THESE STORMS.  OTHER DEVELOPMENT SHOULD OCCUR
NEARER THE COAST THIS EVENING.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. 
MEAN STORM MOTION VECTOR 24040.


...EVANS

284,0962 271,0970 271,1000 284,0992

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 30, 10:55 AM CST	Severe Thunderstorm Watch	SPC	Bosque, Collin, Comanche, Cooke, Coryell, Dallas and 25 more	5 hr
Dec 30, 12:00 PM CST	Tornado Watch	SPC	Atascosa, Bandera, Bastrop, Bexar, Blanco, Burnet and 21 more	6 hr
Dec 30, 1:30 PM CST	Tornado Watch	SPC	Anderson, Bell, Bosque, Camp, Collin, Cooke and 33 more	6 hr
Dec 30, 3:20 PM CST	Tornado Watch	SPC	Anderson, Angelina, Austin, Brazoria, Brazos, Chambers and 29 more	6 hr
Dec 30, 4:35 PM CST	Severe Thunderstorm Watch	SPC	Brooks, Cameron, Hidalgo, Jim Hogg, Kenedy, Starr and 2 more	5 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.