Alert archive / Louisiana / Tornado Watches in 2008

Tornado Watch 876

August 31, 20084 states

The Storm Prediction Center issued this tornado watch at Aug 31, 2008, 8:49 PM CDT for 4 states. It was in force for 10 hr.

The area

The outline as issued.

The facts

Issued
Aug 31, 2008, 8:49 PM CDT (01:49 UTC)
Expired
Sep 1, 2008, 6:33 AM CDT
In force
10 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
70 kt
All 43 counties

Baldwin County, AL, Mobile County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Franklin County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Liberty County, FL, Okaloosa County, FL, Santa Rosa County, FL, Wakulla County, FL, Walton County, FL, Washington County, FL, Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee 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 Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana 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), 81 km from the middle of the area, began a volume at 01:52 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
5%
One or more gusts of 65 knots or more
5%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 31, 10:29 PM CDTTornado WarningLIXPlaquemines46 min
Sep 1, 3:00 AM CDTTornado WarningMOBBaldwin, Mobile60 min
Sep 1, 3:09 AM CDTTornado WarningLIXOrleans, Plaquemines, Saint Bernard21 min
Sep 1, 3:31 AM CDTTornado WarningMOBBaldwin44 min
Sep 1, 3:49 AM CDTTornado WarningLIXPlaquemines26 min
Sep 1, 4:35 AM CDTTornado WarningMOBBaldwin55 min
Sep 1, 4:40 AM CDTTornado WarningMOBEscambia, Santa Rosa50 min
Sep 1, 5:12 AM CDTTornado WarningLIXHancock, Harrison33 min
Sep 1, 5:25 AM CDTTornado WarningMOBBaldwin50 min
Sep 1, 5:31 AM CDTTornado WarningMOBBaldwin59 min
Sep 1, 5:41 AM CDTTornado WarningLIXJefferson, Plaquemines, Saint Charles34 min
Sep 1, 5:46 AM CDTTornado WarningMOBBaldwin, Mobile59 min
Sep 1, 5:57 AM CDTTornado WarningMOBEscambia, Santa Rosa48 min
Sep 1, 6:21 AM CDTTornado WarningMOBBaldwin, Mobile, Washington39 min
Sep 1, 6:28 AM CDTTornado WarningMOBBaldwin, Mobile62 min
Sep 1, 6:31 AM CDTTornado WarningMOBBaldwin44 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 00:00Z, 1.8 hours before the alert went out and 74 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 00:00Z on 2008-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 838 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 00:00Z on 2008-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 113 square meters per square second.1939Sfc1 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
838 J/kg
Mixed-layer CIN
-7 J/kg
Mixed-layer LCL
1135 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
113 m²/s²
0-3 km storm-relative helicity
157 m²/s²
Significant tornado parameter
0.0
Supercell composite
5.3

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 31, 7:47 PM CDTMesoscale DiscussionSPCBaldwin, Mobile88 min
Aug 31, 11:54 PM CDTMesoscale DiscussionSPCBaldwin, Mobile2 hr
Sep 1, 3:51 AM CDTMesoscale DiscussionSPCBaldwin, Mobile114 min
Sep 1, 6:30 AM CDTTornado WatchSPCBaldwin, Clarke, Conecuh, Escambia, Mobile, Monroe and 1 more9 hr
Sep 1, 9:49 AM CDTMesoscale DiscussionSPCBaldwin, Clarke, Conecuh, Escambia, Mobile, Monroe and 1 more86 min
Sep 1, 3:51 PM CDTTornado WatchSPCBaldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more8 hr
Sep 1, 6:28 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Conecuh, Escambia, Mobile and 2 more2 hr

Nearby

Tornado Watches in Louisiana, 2008Tornado Watches in Florida, 2008Tornado Watches in Mississippi, 2008Every 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.