Alert archive / Louisiana / Tornado Watches in 2008

Tornado Watch 72

February 21, 200833 parishes in Louisiana; 9 counties in Mississippi; 4 counties in Texas

The Storm Prediction Center issued this tornado watch at Feb 21, 2008, 8:54 PM CST for 33 parishes in Louisiana; 9 counties in Mississippi; 4 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Feb 21, 2008, 8:54 PM CST (02:54 UTC)
Expired: Feb 22, 2008, 4:00 AM CST
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 46 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Natchitoches Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Forrest County, MS, Greene County, MS, Lamar County, MS, Marion County, MS, Perry County, MS, Pike County, MS, Walthall County, MS, Wilkinson County, MS, Jasper County, TX, Newton County, TX, Orange County, TX, Sabine County, TX

The radar

The Lake Charles radar (KLCH), 55 km from the middle of the area, began a volume at 02:57 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Feb 21, 10:36 PM CST	Flash Flood Warning	SHV	Grant, LaSalle	4 hr
Feb 22, 2:44 AM CST	Severe Thunderstorm Warning	LIX	Amite, Wilkinson	31 min
Feb 22, 3:48 AM CST	Tornado Warning	LIX	Pike	27 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, 2.9 hours before the alert went out and 53 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: 1139 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 643 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 119 m²/s²
0-3 km storm-relative helicity: 137 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 3.1

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 220254
SEL2  
SPC WW 220254
LAZ000-MSZ000-TXZ000-CWZ000-221000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 72
NWS STORM PREDICTION CENTER NORMAN OK
855 PM CST THU FEB 21 2008

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

       MUCH OF SOUTHERN LOUISIANA
       PARTS OF SOUTHEAST MISSISSIPPI
       SMALL PART OF SOUTHEAST TEXAS
       COASTAL WATERS

EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 855 PM
UNTIL 400 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 APPROXIMATELY ALONG AND 115 STATUTE
MILES EAST AND WEST OF A LINE FROM 70 MILES SOUTHWEST OF
INTRACOASTAL CITY LOUISIANA TO 10 MILES NORTH NORTHEAST OF
NATCHEZ MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).

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 70. WATCH NUMBER 70 WILL NOT BE IN EFFECT AFTER 855
PM CST. CONTINUE...WW 71...

DISCUSSION...SEVERE THUNDERSTORMS EXPECTED TO CONTINUE DEVELOPING
AHEAD OF COLD FRONT ACROSS WATCH AREA MUCH OF NIGHT.  WITH APPROACH
OF UPPER TROUGH SHEAR PROFILES WILL SUPPORT SUPERCELLS AS LOW LEVEL
JET INCREASES TO 30-40KT.  IN ADDITION TO LARGE HAIL/TORNADOES WILL
BE POSSIBLE WITH ANY SUPERCELL BOTH ALONG AND TO S OF E/W FRONTAL
ZONE WHICH EXTENDS EWD INTO SERN MS.

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
450. MEAN STORM MOTION VECTOR 24035.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 21, 6:53 PM CST	Severe Thunderstorm Watch	SPC	Bienville, Caldwell, Catahoula, Claiborne, Concordia, East Carroll and 13 more	7 hr
Feb 21, 7:22 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more	83 min
Feb 21, 10:31 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more	119 min
Feb 21, 10:59 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more	2 hr
Feb 22, 1:05 AM CST	Mesoscale Discussion	SPC	Attala, Carroll, Choctaw, Holmes, Humphreys, Issaquena and 15 more	55 min
Feb 22, 1:44 AM CST	Severe Thunderstorm Watch	SPC	Clarke, Copiah, Covington, Franklin, Jasper, Jefferson Davis and 12 more	5 hr
Feb 22, 4:41 AM CST	Mesoscale Discussion	SPC	Clarke, Covington, Forrest, Jones, Lamar, Marion and 2 more	64 min
Feb 22, 5:13 AM CST	Mesoscale Discussion	SPC	Austin, Bastrop, Caldwell, Colorado, DeWitt, Fayette and 7 more	92 min

Nearby

Tornado Watches in Louisiana, 2008 Tornado Watches in Mississippi, 2008 Tornado Watches in Texas, 2008 Every tornado watch in 2008

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.