Alert archive / Texas / Tornado Watches in 2002

Tornado Watch 790

December 19, 20024 parishes in Louisiana; 23 counties in Texas

The Storm Prediction Center issued this tornado watch at Dec 19, 2002, 12:30 AM CST for 4 parishes in Louisiana; 23 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Dec 19, 2002, 12:30 AM CST (06:30 UTC)
Expired: Dec 19, 2002, 7:00 AM CST
In force: 7 hr
Issued by: the Storm Prediction Center

All 27 counties

Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Evangeline Parish, LA, Austin County, TX, Brazoria County, TX, Chambers County, TX, Colorado County, TX, DeWitt County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jasper County, TX, Jefferson County, TX, Lavaca County, TX, Liberty County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, San Jacinto County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 48 km from the middle of the area, began a volume at 06:33 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

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

Issued	Product	Office	Counties	Lasted
Dec 19, 4:54 AM CST	Tornado Warning	LCH	Newton	36 min

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 6.5 hours before the alert went out and 225 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: 903 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 534 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 183 m²/s²
0-3 km storm-relative helicity: 228 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 4.6

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 190630
SEL0  
SPC WW 190630
LAZ000-TXZ000-CWZ000-191300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 790
STORM PREDICTION CENTER NORMAN OK
1230 AM CST THU DEC 19 2002

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

   SOUTHWEST LOUISIANA                          
   SOUTHEAST TEXAS                              
   COASTAL WATERS                     

EFFECTIVE THIS THURSDAY MORNING FROM 1230 AM UNTIL 700 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 100 STATUTE MILES EAST AND WEST
OF A LINE FROM 45 MILES EAST OF VICTORIA TEXAS TO 65 MILES NORTH
NORTHWEST OF LAKE CHARLES LOUISIANA.

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 788...WW 789...

DISCUSSION...LARGE SCALE ASCENT WILL CONTINUE TO OVERSPREAD
MODERATE INSTABILITY ACROSS SERN TX OVERNIGHT...AHEAD OF
PROGRESSIVE SHORTWAVE TROUGH AND ASSOCIATED EXIT REGION OF
MID/UPPER LEVEL JET NOW SPREADING ACROSS CENTRAL TX.  DEEP LAYER
SHEAR AND INSTABILITY WILL SUPPORT SUPERCELLS AND SMALL LINES.  IF
LOW LEVEL WINDS RESPOND TO APPROACHING SYSTEM AND INCREASE/BACK
SLIGHTLY...TORNADO THREAT WILL LIKEWISE INCREASE THROUGH THE EARLY
MORNING.

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 24040.


...EVANS

305,0915 285,0943 285,0974 305,0951

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 18, 8:55 PM CST	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 13 more	6 hr
Dec 19, 2:25 AM CST	Tornado Watch	SPC	Avoyelles, Bienville, Caldwell, Catahoula, Claiborne, Concordia and 20 more	8 hr
Dec 19, 6:30 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 26 more	6 hr
Dec 19, 9:35 AM CST	Tornado Watch	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 2 more	5 hr
Dec 19, 11:40 AM CST	Tornado Watch	SPC	Ascension, Assumption, Livingston, Orleans, Saint Bernard, Saint Charles and 7 more	6 hr

Nearby

Tornado Watches in Texas, 2002 Tornado Watches in Louisiana, 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.