Alert archive / Louisiana / Tornado Watches in 2003

Tornado Watch 955

November 17, 20038 parishes in Louisiana; 4 counties in Texas

The Storm Prediction Center issued this tornado watch at Nov 17, 2003, 11:50 PM CST for 8 parishes in Louisiana; 4 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Nov 17, 2003, 11:50 PM CST (05:50 UTC)
Expired: Nov 18, 2003, 5:00 AM CST
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Acadia Parish, LA, Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Vernon Parish, LA, Jasper County, TX, Jefferson County, TX, Newton County, TX, Orange County, TX

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Nov 18, 12:11 AM CST	Tornado Warning	LCH	Hardin, Jasper, Tyler	34 min
Nov 18, 12:21 AM CST	Tornado Warning	LCH	Jefferson	24 min
Nov 18, 12:26 AM CST	Tornado Warning	LCH	Vernon	34 min
Nov 18, 12:47 AM CST	Tornado Warning	LCH	Jefferson	28 min
Nov 18, 1:10 AM CST	Tornado Warning	LCH	Vernon	35 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 5.8 hours before the alert went out and 46 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: 877 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 631 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 200 m²/s²
0-3 km storm-relative helicity: 222 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 7.0

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 180550
SEL5  
SPC WW 180550
LAZ000-TXZ000-CWZ000-181100-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 955 
NWS STORM PREDICTION CENTER NORMAN OK 
1150 PM CST MON NOV 17 2003

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

       SOUTHWEST LOUISIANA
       EXTREME SOUTHEAST TEXAS
       COASTAL WATERS

EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 1150 PM UNTIL
500 AM CST.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 60 STATUTE MILES EAST AND WEST
OF A LINE FROM 10 MILES NORTH NORTHEAST OF FORT POLK LOUISIANA TO
50 MILES SOUTH SOUTHEAST OF PORT ARTHUR 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...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 952. WATCH NUMBER 952 WILL NOT BE IN EFFECT AFTER
1150 PM CST. CONTINUE...WW 953...WW 954...


DISCUSSION...PRE-FRONTAL THUNDERSTORM BAND IS MOVING EWD ACROSS SE
TX AND WILL BE MERGING WITH A CONFLUENCE BOUNDARY A COUNTY OR TWO W
OF THE SABINE RIVER.  LOWER 70 DEWPOINTS AND STRONG LOW-LEVEL SHEAR
PERSIST ALONG AND E OF THE CONFLUENCE BOUNDARY...WHERE A THREAT FOR
SUPERCELLS AND A FEW TORNADOES WILL CONTINUE INTO THE EARLY MORNING
HOURS ACROSS EXTREME SE TX INTO SW LA.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 22030.


...THOMPSON

311,0920 291,0924 291,0944 311,0940

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 17, 7:48 PM CST	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Webster	87 min
Nov 17, 8:10 PM CST	Mesoscale Discussion	SPC	Beauregard, Calcasieu, Natchitoches, Sabine, Vernon	95 min
Nov 17, 9:25 PM CST	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 12 more	7 hr
Nov 17, 10:53 PM CST	Mesoscale Discussion	SPC	Beauregard, Calcasieu	97 min
Nov 17, 11:44 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caldwell, Claiborne, De Soto, Grant and 11 more	91 min
Nov 18, 2:08 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Avoyelles, Catahoula, Concordia, East Baton Rouge and 25 more	97 min
Nov 18, 2:25 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more	6 hr
Nov 18, 4:48 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberville and 17 more	117 min
Nov 18, 6:08 AM CST	Mesoscale Discussion	SPC	Ascension, Jefferson, Lafourche, Livingston, Orleans, Plaquemines and 8 more	2 hr
Nov 18, 6:55 AM CST	Tornado Watch	SPC	Ascension, Assumption, East Baton Rouge, Jefferson, Lafourche, Livingston and 11 more	5 hr
Nov 18, 10:30 AM CST	Mesoscale Discussion	SPC	Saint Bernard	90 min
Nov 17, 6:55 PM CST	Severe Thunderstorm Watch	SPC	Austin, Brazoria, Colorado, Fort Bend, Grimes, Harris and 12 more	5 hr

Nearby

Tornado Watches in Louisiana, 2003 Tornado Watches in Texas, 2003 Every tornado watch in 2003

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.