Alert archive / Texas / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 813

December 30, 20028 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Dec 30, 2002, 4:35 PM CST for 8 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Dec 30, 2002, 4:35 PM CST (22:35 UTC)
Expired: Dec 30, 2002, 10:00 PM CST
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Brooks County, TX, Cameron County, TX, Hidalgo County, TX, Jim Hogg County, TX, Kenedy County, TX, Starr County, TX, Willacy County, TX, Zapata County, TX

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Dec 30, 4:56 PM CST	Severe Thunderstorm Warning	BRO	Jim Hogg, Zapata	34 min
Dec 30, 5:01 PM CST	Severe Thunderstorm Warning	BRO	Jim Hogg, Starr, Zapata	44 min
Dec 30, 5:09 PM CST	Tornado Warning	BRO	Jim Hogg, Zapata	51 min
Dec 30, 5:12 PM CST	Tornado Warning	BRO	Brooks, Jim Hogg, Starr, Zapata	48 min
Dec 30, 5:35 PM CST	Tornado Warning	BRO	Brooks	40 min
Dec 30, 5:59 PM CST	Tornado Warning	BRO	Brooks, Hidalgo, Kenedy	46 min

The nearest sounding before it

Brownsville Intl, TX (KBRO), launched 12:00Z, 10.6 hours before the alert went out and 110 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: 126 J/kg
Mixed-layer CIN: -396 J/kg
Mixed-layer LCL: 665 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 149 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

808 
WWUS20 KWNS 302237
SEL3  
SPC WW 302235
TXZ000-CWZ000-310400-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 813
STORM PREDICTION CENTER NORMAN OK
435 PM CST MON DEC 30 2002

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

DEEP SOUTH TEXAS                              
ADJACENT COASTAL WATERS                     

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 435 PM UNTIL 1000
PM CST.

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

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 65 STATUTE MILES
EAST AND WEST OF A LINE FROM 75 MILES NORTH OF MCALLEN TEXAS TO 20
MILES SOUTH OF MCALLEN TEXAS.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...  CONTINUE...WW 809...WW 810...WW
811...WW 812...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THE NEXT
1-2 HOURS IN THE AREA BETWEEN LAREDO AND HARLINGEN.  A STRONG MID
LEVEL TROUGH IS MOVING ESEWD FROM THE BIG BEND AREA...AND IS
CONTRIBUTING TO ENHANCED ASCENT ALONG A SURFACE BOUNDARY
IMMEDIATELY SE OF LRD.  DEEPENING CLOUDS IN THIS BAND SUGGEST THE
CAP WILL SOON BE WEAKENED ENOUGH FOR STORM DEVELOPMENT.  SBCAPE
VALUES NEAR 2500 J/KG AND DEEP LAYER SPEED SHEAR BENEATH THE MID
LEVEL JET WILL SUPPORT SEVERE STORMS...WITH LARGE HAIL AND DAMAGING
WINDS THE MAIN THREATS THROUGH THIS EVENING.


AVIATION...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 450.  MEAN STORM
MOTION VECTOR 27030.


...THOMPSON

271,0971 255,0971 255,0991 271,0991

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, 2:50 PM CST	Tornado Watch	SPC	Aransas, Bee, Calhoun, Duval, Goliad, Jim Wells and 9 more	6 hr
Dec 30, 3:20 PM CST	Tornado Watch	SPC	Anderson, Angelina, Austin, Brazoria, Brazos, Chambers and 29 more	6 hr

Nearby

Severe Thunderstorm Watches in Texas, 2002 Every severe thunderstorm 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.