Alert archive / Mississippi / Tornado Watches in 2008

Tornado Watch 207

April 18, 200816 parishes in Louisiana; 33 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Apr 18, 2008, 3:43 PM CDT for 16 parishes in Louisiana; 33 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Apr 18, 2008, 3:43 PM CDT (20:43 UTC)
Expired
Apr 18, 2008, 10:55 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 49 counties

Ascension Parish, LA, Assumption Parish, LA, Jefferson 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 Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Hinds County, MS, Jackson County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 98 km from the middle of the area, began a volume at 20:43 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
30%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 18, 4:06 PM CDTSevere Thunderstorm WarningLIXLivingston, Saint Helena, Saint Tammany, Tangipahoa, Washington39 min
Apr 18, 4:08 PM CDTSevere Thunderstorm WarningJANHinds, Rankin52 min
Apr 18, 4:25 PM CDTSevere Thunderstorm WarningLIXPike, Walthall65 min
Apr 18, 4:33 PM CDTFlash Flood WarningJANHinds, Madison, Rankin93 min
Apr 18, 4:40 PM CDTTornado WarningLIXPike, Walthall35 min
Apr 18, 4:54 PM CDTSevere Thunderstorm WarningJANLeake, Scott51 min
Apr 18, 5:09 PM CDTSevere Thunderstorm WarningJANMarion52 min
Apr 18, 5:27 PM CDTSevere Thunderstorm WarningJANAttala, Choctaw, Leake, Neshoba, Winston35 min
Apr 18, 5:44 PM CDTSevere Thunderstorm WarningJANScott, Smith46 min
Apr 18, 5:48 PM CDTTornado WarningJANLamar, Marion41 min
Apr 18, 6:06 PM CDTTornado WarningLIXSaint Tammany24 min
Apr 18, 6:07 PM CDTTornado WarningJANForrest, Lamar53 min
Apr 18, 6:38 PM CDTSevere Thunderstorm WarningMOBPerry52 min
Apr 18, 6:40 PM CDTSevere Thunderstorm WarningJANKemper, Lauderdale, Neshoba, Newton65 min
Apr 18, 7:36 PM CDTTornado WarningMOBGreene39 min
Apr 18, 8:46 PM CDTFlash Flood WarningMOBGreene3 hr
Apr 18, 9:16 PM CDTSevere Thunderstorm WarningMOBGreene44 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

Jackson, MS (KJAN), launched 12:00Z, 8.7 hours before the alert went out and 104 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, Jackson, MS at 12:00Z on 2008-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Jackson, MS at 12:00Z on 2008-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 243 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
810 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
243 m²/s²
0-3 km storm-relative helicity
326 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 182044
SEL7  
SPC WW 182044
LAZ000-MSZ000-CWZ000-190300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 207
NWS STORM PREDICTION CENTER NORMAN OK
345 PM CDT FRI APR 18 2008

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

       SOUTHEASTERN LOUISIANA
       PARTS OF CENTRAL AND SOUTHERN MISSISSIPPI
       COASTAL WATERS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 345 PM UNTIL
1000 PM CDT.

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 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH NORTHWEST OF
MERIDIAN MISSISSIPPI TO 30 MILES SOUTHEAST OF HOUMA LOUISIANA. 
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).

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...THUNDERSTORMS DEVELOPING IN AREA OF UNSTABLE AIR MASS
AHEAD OF APPROACHING S/WV TROUGH.  SHEAR PROFILES ARE FAVORABLE FOR
SUPERCELLS AND WITH MLCAPES TO 1000 J/KG WIND DAMAGE AND TORNADOES
WILL BE POSSIBLE WITH SUPERCELLS.  ACTIVITY WILL DEVELOP EWD ACROSS
WATCH THRU THE EVENING.

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
500. MEAN STORM MOTION VECTOR 24030.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 18, 5:08 PM CDTMesoscale DiscussionSPCBibb, Colbert, Cullman, Fayette, Franklin, Lamar and 9 more37 min
Apr 18, 6:07 PM CDTMesoscale DiscussionSPCBaldwin, Choctaw, Clarke, Conecuh, Dallas, Escambia and 7 more53 min
Apr 18, 6:43 PM CDTTornado WatchSPCBaldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 6 more7 hr
Apr 18, 3:24 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberville, Livingston and 8 more2 hr
Apr 18, 3:07 PM CDTMesoscale DiscussionSPCBenton, DeSoto, Marshall, Tate, Tunica113 min

Nearby

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