Alert archive / Louisiana / Tornado Watches in 2007

Tornado Watch 1

January 4, 200725 parishes in Louisiana; 4 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Jan 4, 2007, 1:44 PM CST for 25 parishes in Louisiana; 4 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Jan 4, 2007, 1:44 PM CST (19:44 UTC)
Expired: Jan 4, 2007, 9:00 PM CST
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 29 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, Hancock County, MS, Pearl River County, MS, Pike 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: 30%
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: 10%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jan 4, 3:40 PM CST	Tornado Warning	LCH	Iberia	18 min
Jan 4, 3:55 PM CST	Severe Thunderstorm Warning	LCH	Saint Martin	65 min
Jan 4, 4:20 PM CST	Tornado Warning	LIX	Iberville, Pointe Coupee	25 min
Jan 4, 4:37 PM CST	Severe Thunderstorm Warning	LIX	West Baton Rouge	38 min
Jan 4, 4:43 PM CST	Tornado Warning	LIX	East Feliciana, Pointe Coupee, West Feliciana	47 min
Jan 4, 4:51 PM CST	Flash Flood Warning	LIX	Iberville	4 hr
Jan 4, 6:39 PM CST	Tornado Warning	LIX	Terrebonne	23 min
Jan 4, 6:58 PM CST	Tornado Warning	LIX	Lafourche	32 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

Slidell Radar S, LA (KSIL), launched 12:00Z, 7.7 hours before the alert went out and 108 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: 662 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 140 m²/s²
0-3 km storm-relative helicity: 336 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 041944
SEL1  
SPC WW 041944
LAZ000-MSZ000-CWZ000-050300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 1
NWS STORM PREDICTION CENTER NORMAN OK
145 PM CST THU JAN 4 2007

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

       SOUTHEAST LOUISIANA
       SOUTHERN MISSISSIPPI
       COASTAL WATERS

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 145 PM UNTIL
900 PM 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 APPROXIMATELY ALONG AND 70 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 55 MILES SOUTHWEST OF BATON
ROUGE LOUISIANA TO 40 MILES SOUTHEAST OF SLIDELL LOUISIANA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).

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.

DISCUSSION...SCATTERED THUNDERSTORMS ARE EXPECTED TO INCREASE THIS
AFTERNOON ACROSS SOUTHEAST LA...AHEAD OF UPPER TROUGH AND ASSOCIATED
SURFACE COLD FRONT.  18Z LIX SOUNDING CONFIRMS FAVORABLE LOW LEVEL
AND DEEP LAYER VERTICAL SHEAR PROFILES FOR ORGANIZED/SUPERCELL
STORMS CAPABLE OF DAMAGING WINDS AND TORNADOES.  THREAT SHOULD
INCREASE WITH TIME AS CONTINUED SOUTHERLY LOW LEVEL WINDS TRANSPORT
GULF MOISTURE INLAND.

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 450.
MEAN STORM MOTION VECTOR 24030.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 4, 10:09 AM CST	Mesoscale Discussion	SPC	Assumption, Iberia, Jefferson, Lafourche, Saint Charles, Saint James and 3 more	3 hr
Jan 4, 3:22 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 17 more	83 min

Nearby

Tornado Watches in Louisiana, 2007 Tornado Watches in Mississippi, 2007 Every tornado watch in 2007

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.