Alert archive / Louisiana / Tornado Watches in 2006

Tornado Watch 892

December 30, 200612 parishes in Louisiana; 12 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Dec 30, 2006, 1:30 PM CST for 12 parishes in Louisiana; 12 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Dec 30, 2006, 1:30 PM CST (19:30 UTC)
Expired: Dec 30, 2006, 8:00 PM CST
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 24 counties

Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Lamar County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS, Walthall County, MS

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%

Discussions around it

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

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 7.5 hours before the alert went out and 16 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 674 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 413 m²/s²
0-3 km storm-relative helicity: 525 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.

000 
WWUS20 KWNS 301932
SEL2  
SPC WW 301932
LAZ000-MSZ000-CWZ000-310200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 892
NWS STORM PREDICTION CENTER NORMAN OK
130 PM CST SAT DEC 30 2006

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

       SOUTHEAST LOUISIANA
       SOUTHEAST MISSISSIPPI
       COASTAL WATERS

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 130 PM UNTIL
800 PM 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 55 STATUTE
MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH NORTHWEST OF
GULFPORT MISSISSIPPI TO 45 MILES SOUTHWEST OF BOOTHVILLE
LOUISIANA.  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 891. WATCH NUMBER 891 WILL NOT BE IN EFFECT AFTER
130 PM CST. 

DISCUSSION...WARM FRONTAL BOUNDARY HAS MOVED NWD INTO SERN LA NOW
AND AIR MASS HAS DESTABILIZED TO A POINT WHERE MLCAPE IS AROUND OR
JUST ABOVE 500 J/KG.  18Z RAOB FROM KSIL SHOW STRONG VERTICAL SHEAR
PROFILES WITH BOTH 0-1KM AND 0-3 KM HELICITY AROUND 445 M2/S2. 
THUS...ENVIRONMENT REMAINS FAVORABLE FOR TORNADOES AND DAMAGING
WINDS ACROSS THE REGION.

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
400. MEAN STORM MOTION VECTOR 21035.


...MCCARTHY

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 29, 7:52 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 18 more	53 min
Dec 29, 8:19 PM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 23 more	10 hr
Dec 29, 11:41 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 24 more	94 min
Dec 30, 3:14 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Assumption, Avoyelles, Beauregard, Bienville and 30 more	91 min
Dec 30, 5:43 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Cameron and 19 more	6 hr
Dec 30, 7:49 AM CST	Mesoscale Discussion	SPC	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint John the Baptist and 3 more	86 min
Dec 30, 8:43 AM CST	Tornado Watch	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 5 more	5 hr
Dec 30, 10:22 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Jefferson, Lafourche, Livingston, Orleans and 9 more	83 min
Dec 30, 1:13 PM CST	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Saint Bernard, Saint Charles, Saint Tammany	62 min
Dec 30, 5:45 PM CST	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 4 more	60 min

Nearby

Tornado Watches in Louisiana, 2006 Tornado Watches in Mississippi, 2006 Every tornado watch in 2006

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.