Alert archive / Louisiana / Tornado Watches in 2009

Tornado Watch 145

April 12, 200932 parishes in Louisiana; 31 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Apr 12, 2009, 1:53 PM CDT for 32 parishes in Louisiana; 31 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Apr 12, 2009, 1:53 PM CDT (18:53 UTC)
Expired
Apr 12, 2009, 8:35 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 63 counties

Ascension Parish, LA, Assumption Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Franklin Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Richland 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, Tangipahoa Parish, LA, Tensas Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Claiborne County, MS, Copiah County, MS, Covington County, MS, Franklin County, MS, Hancock County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lamar County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Pearl River County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS

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
40%
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

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

IssuedProductOfficeCountiesLasted
Apr 12, 2:24 PM CDTSevere Thunderstorm WarningLIXIberville, Pointe Coupee, West Baton Rouge, West Feliciana66 min
Apr 12, 3:05 PM CDTSevere Thunderstorm WarningJANCatahoula, Concordia40 min
Apr 12, 3:53 PM CDTSevere Thunderstorm WarningJANConcordia52 min
Apr 12, 4:38 PM CDTSevere Thunderstorm WarningJANCatahoula, Concordia52 min
Apr 12, 4:45 PM CDTSevere Thunderstorm WarningJANMorehouse45 min
Apr 12, 5:06 PM CDTSevere Thunderstorm WarningJANAdams, Jefferson39 min
Apr 12, 5:38 PM CDTSevere Thunderstorm WarningLIXPointe Coupee18 min
Apr 12, 5:40 PM CDTSevere Thunderstorm WarningJANAdams, Franklin, Jefferson50 min
Apr 12, 5:54 PM CDTSevere Thunderstorm WarningLIXPointe Coupee, West Feliciana18 min
Apr 12, 6:25 PM CDTSevere Thunderstorm WarningJANFranklin, Lincoln65 min
Apr 12, 6:44 PM CDTSevere Thunderstorm WarningJANCopiah61 min
Apr 12, 7:19 PM CDTSevere Thunderstorm WarningJANJefferson Davis, Lawrence, Simpson56 min
Apr 12, 7:26 PM CDTSevere Thunderstorm WarningLIXEast Baton Rouge, West Baton Rouge21 min
Apr 12, 7:28 PM CDTTornado WarningJANCopiah, Jefferson Davis, Lawrence, Simpson62 min
Apr 12, 7:36 PM CDTSevere Thunderstorm WarningLIXAmite, Pike, Walthall54 min
Apr 12, 7:42 PM CDTFlash Flood WarningJANFranklin, Lincoln3 hr
Apr 12, 7:46 PM CDTFlash Flood WarningLIXAmite, Pike2 hr
Apr 12, 7:55 PM CDTTornado WarningJANCovington, Jefferson Davis, Simpson, Smith65 min
Apr 12, 8:12 PM CDTSevere Thunderstorm WarningJANCovington, Jefferson Davis63 min
Apr 12, 8:17 PM CDTFlash Flood WarningJANJefferson Davis, Lawrence3 hr
Apr 12, 8:32 PM CDTSevere Thunderstorm WarningLIXEast Feliciana15 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, 6.9 hours before the alert went out and 184 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 2009-04-12Temperature 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 2009-04-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 152 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
971 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
152 m²/s²
0-3 km storm-relative helicity
186 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 12, 7:13 AM CDTMesoscale DiscussionSPCEast Carroll, Morehouse, Union, West Carroll92 min
Apr 12, 7:39 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 11 more66 min
Apr 12, 7:58 AM CDTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more8 hr
Apr 12, 9:19 AM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Caldwell, De Soto, Jackson and 10 more56 min
Apr 12, 9:30 AM CDTSevere Thunderstorm WatchSPCBienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more7 hr
Apr 12, 10:53 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 2 more2 hr
Apr 12, 12:00 PM CDTMesoscale DiscussionSPCBienville, Caldwell, Claiborne, Jackson, Lincoln, Morehouse and 8 more90 min
Apr 12, 1:02 PM CDTMesoscale DiscussionSPCAscension, Assumption, Concordia, East Baton Rouge, East Feliciana, Franklin and 14 more88 min
Apr 12, 5:49 PM CDTMesoscale DiscussionSPCCatahoula, Concordia, East Carroll, Franklin, Madison, Richland and 2 more86 min

Nearby

Tornado Watches in Louisiana, 2009Tornado Watches in Mississippi, 2009Every tornado watch in 2009

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.