Alert archive / Louisiana / Tornado Watches in 2007

Tornado Watch 729

October 22, 20074 states

The Storm Prediction Center issued this tornado watch at Oct 22, 2007, 5:11 PM CDT for 4 states. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Oct 22, 2007, 5:11 PM CDT (22:11 UTC)
Expired
Oct 23, 2007, 1:00 AM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 27 counties

Baldwin County, AL, Clarke County, AL, Conecuh County, AL, Escambia County, AL, Mobile County, AL, Monroe County, AL, Washington County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Jefferson Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Terrebonne Parish, LA, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Perry County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 110 km from the middle of the area, began a volume at 22:11 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

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

IssuedProductOfficeCountiesLasted
Oct 22, 5:43 PM CDTFlash Flood WarningLIXSaint Tammany, Washington3 hr
Oct 22, 6:05 PM CDTFlash Flood WarningLIXSaint Tammany3 hr
Oct 22, 6:47 PM CDTTornado WarningMOBClarke, Mobile, Washington43 min
Oct 22, 6:52 PM CDTFlash Flood WarningLIXSaint Charles3 hr
Oct 22, 7:31 PM CDTTornado WarningMOBWashington29 min
Oct 22, 7:46 PM CDTTornado WarningLIXHarrison29 min
Oct 22, 7:57 PM CDTFlash Flood WarningLIXPearl River3 hr
Oct 22, 8:30 PM CDTFlash Flood WarningLIXSaint Tammany3 hr
Oct 22, 8:32 PM CDTTornado WarningMOBClarke, Washington43 min
Oct 22, 9:12 PM CDTTornado WarningMOBClarke, Wilcox33 min
Oct 22, 9:52 PM CDTFlash Flood WarningMOBChoctaw, Clarke, Washington6 hr
Oct 22, 9:52 PM CDTFlash Flood WarningMOBChoctaw, Clarke, Washington6 hr
Oct 22, 10:26 PM CDTTornado WarningMOBClarke, Wilcox18 min
Oct 23, 12:04 AM CDTFlash Flood WarningMOBBaldwin, Mobile, Monroe, Wilcox6 hr

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, 10.2 hours before the alert went out and 39 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-pSkew-T log-p diagram, Slidell Radar S, LA at 12:00Z on 2007-10-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 595 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 12:00Z on 2007-10-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 66 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
595 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
597 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
66 m²/s²
0-3 km storm-relative helicity
109 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.0

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 222205
SEL9  
SPC WW 222205
ALZ000-FLZ000-LAZ000-MSZ000-CWZ000-230400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 729
NWS STORM PREDICTION CENTER NORMAN OK
505 PM CDT MON OCT 22 2007

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

       SOUTHWEST ALABAMA
       WESTERN FLORIDA PENINSULA
       SOUTHEAST LOUISIANA
       SOUTHERN MISSISSIPPI
       COASTAL WATERS

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 505 PM UNTIL
1100 PM CDT.

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 50 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST OF HOUMA
LOUISIANA TO 30 MILES SOUTH SOUTHEAST OF EVERGREEN ALABAMA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU9).

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...SMALL AND ISOLATED SUPERCELLS ARE DRIFTING ONSHORE THIS
AFTERNOON FROM SOUTHEASTERN LA TO MOBILE BAY.  PRESENCE OF AMPLE
MOISTURE...STRONG VERTICAL SHEAR...AND APPROACHING UPPER TROUGH
SUPPORT A RISK OF ISOLATED TORNADOES THROUGH THE EVENING HOURS.

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.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 21, 11:48 PM CDTMesoscale DiscussionSPCMobile2 hr
Oct 22, 3:37 AM CDTMesoscale DiscussionSPCBaldwin, Mobile83 min
Oct 22, 4:38 PM CDTMesoscale DiscussionSPCBaldwin, Mobile2 hr
Oct 22, 1:58 PM CDTMesoscale DiscussionSPCAcadia, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 17 more92 min
Oct 22, 6:51 PM CDTMesoscale DiscussionSPCJefferson, Lafourche, Orleans, Saint Bernard, Saint Tammany114 min

Nearby

Tornado Watches in Louisiana, 2007Tornado Watches in Mississippi, 2007Tornado Watches in Alabama, 2007Every 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; radar from the NEXRAD Level II archive.