Alert archive / Louisiana / Tornado Watches in 2002

Tornado Watch 699

September 25, 20024 states

The Storm Prediction Center issued this tornado watch at Sep 25, 2002, 3:15 AM CDT for 4 states. It was in force for 10 hr.

The area

The outline as issued.

The facts

Issued: Sep 25, 2002, 3:15 AM CDT (08:15 UTC)
Expired: Sep 25, 2002, 1:00 PM CDT
In force: 10 hr
Issued by: the Storm Prediction Center

All 22 counties

Baldwin County, AL, Mobile County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, 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, George County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 97 km from the middle of the area, began a volume at 08:17 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

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

Issued	Product	Office	Counties	Lasted
Sep 25, 3:53 AM CDT	Flash Flood Warning	MOB	Mobile	9 hr
Sep 25, 4:36 AM CDT	Tornado Warning	LIX	Plaquemines	20 hr
Sep 25, 5:39 AM CDT	Flash Flood Warning	MOB	Baldwin	7 hr
Sep 25, 5:40 AM CDT	Flash Flood Warning	MOB	Baldwin	7 hr

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 8.3 hours before the alert went out and 59 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: 371 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 488 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 78 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 250819
SEL9  
SPC WW 250815
ALZ000-FLZ000-LAZ000-MSZ000-CWZ000-251800-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 699
STORM PREDICTION CENTER NORMAN OK
315 AM CDT WED SEP 25 2002

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

   EXTREME SOUTHERN ALABAMA                            
   WESTERN FLORIDA PANHANDLE                            
   SOUTHEAST LOUISIANA                          
   EXTREME SOUTHERN MISSISSIPPI                        
   AND ADJACENT COASTAL WATERS                     

EFFECTIVE THIS WEDNESDAY MORNING AND AFTERNOON FROM 315 AM UNTIL
100 PM CDT.

TORNADOES...HAIL TO 0.5 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 NORTH AND
SOUTH OF A LINE FROM 25 MILES NORTH NORTHWEST OF HOUMA LOUISIANA TO
45 MILES EAST SOUTHEAST OF PENSACOLA FLORIDA.

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 ALONG AND OFF THE GULF COAST
ARE EXPECTED TO SLOWLY SPREAD INLAND THROUGH THE MORNING HOURS. 
VERY STRONG LOW LEVEL VERTICAL SHEAR PROFILES ARE PRESENT...WITH
LOCAL VADS AND 06Z SIL SOUNDING SHOWING 1KM SHEAR OVER 30 KNOTS AND
3KM HELICITY APPROACHING 500 M2/S2.  POTENTIAL EXISTS FOR ISOLATED
TORNADOES IN STRONGER CELLS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH...EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. 
MEAN STORM MOTION VECTOR 12020.

...HART

304,0904 310,0862 292,0862 290,0904

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 25, 12:30 PM CDT	Tornado Watch	SPC	Baldwin, Geneva, Houston, Mobile	12 hr

Nearby

Tornado Watches in Louisiana, 2002 Tornado Watches in Mississippi, 2002 Tornado Watches in Florida, 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.