Alert archive / Louisiana / Tornado Watches in 2009

Tornado Watch 772

October 22, 200946 parishes in Louisiana; 9 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Oct 22, 2009, 11:58 AM CDT for 46 parishes in Louisiana; 9 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Oct 22, 2009, 11:58 AM CDT (16:58 UTC)
Expired
Oct 22, 2009, 7:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
60 kt
All 55 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Livingston Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tensas Parish, LA, Union Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Franklin County, MS, Issaquena County, MS, Jefferson County, MS, Sharkey County, MS, Warren County, MS, Wilkinson County, MS

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
50%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
20%
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
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Oct 22, 12:05 PM CDTTornado WarningSHVNatchitoches16 min
Oct 22, 12:12 PM CDTFlash Flood WarningLCHCameron3 hr
Oct 22, 12:18 PM CDTTornado WarningSHVNatchitoches27 min
Oct 22, 12:29 PM CDTTornado WarningLCHAcadia, Allen, Evangeline, Jefferson Davis61 min
Oct 22, 12:39 PM CDTFlash Flood WarningSHVNatchitoches, Red River111 min
Oct 22, 12:39 PM CDTTornado WarningSHVBienville, Natchitoches, Winn35 min
Oct 22, 12:51 PM CDTSevere Thunderstorm WarningLCHCameron, Vermilion54 min
Oct 22, 1:07 PM CDTFlash Flood WarningLCHAllen, Beauregard, Calcasieu, Jefferson Davis3 hr
Oct 22, 1:09 PM CDTSevere Thunderstorm WarningLCHAcadia, Cameron, Evangeline, Jefferson Davis, Lafayette, Saint Landry66 min
Oct 22, 1:11 PM CDTSevere Thunderstorm WarningSHVBienville, Jackson, Lincoln, Winn49 min
Oct 22, 1:13 PM CDTTornado WarningLCHAllen, Evangeline, Rapides32 min
Oct 22, 1:27 PM CDTSevere Thunderstorm WarningLCHRapides48 min
Oct 22, 1:37 PM CDTTornado WarningLCHRapides23 min
Oct 22, 1:56 PM CDTSevere Thunderstorm WarningLCHAcadia, Iberia, Lafayette, Saint Landry, Saint Martin, St. Mary and 1 more64 min
Oct 22, 2:11 PM CDTSevere Thunderstorm WarningLCHAcadia, Avoyelles, Evangeline, Lafayette, Rapides, Saint Landry and 1 more64 min
Oct 22, 2:38 PM CDTSevere Thunderstorm WarningJANCatahoula, Concordia82 min
Oct 22, 2:50 PM CDTFlash Flood WarningLCHRapides3 hr
Oct 22, 4:04 PM CDTSevere Thunderstorm WarningLCHSaint Martin, St. Mary41 min
Oct 22, 4:47 PM CDTSevere Thunderstorm WarningJANFranklin, Madison, Tensas58 min
Oct 22, 5:28 PM CDTSevere Thunderstorm WarningJANEast Carroll, Franklin, Madison, Richland62 min
Oct 22, 5:59 PM CDTSevere Thunderstorm WarningJANEast Carroll, Madison, West Carroll61 min
Oct 22, 6:00 PM CDTFlash Flood WarningJANEast Carroll3 hr
Oct 22, 6:45 PM CDTSevere Thunderstorm WarningJANEast Carroll60 min
Oct 22, 6:55 PM CDTSevere Thunderstorm WarningJANCopiah, Franklin, Jefferson, Lincoln65 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

Shreveport, LA (KSHV), launched 12:00Z, 5.0 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, Shreveport, LA at 12:00Z on 2009-10-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 294 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, Shreveport, LA at 12:00Z on 2009-10-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 224 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
294 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
469 m above ground
0-6 km bulk shear
57 kt
0-1 km storm-relative helicity
224 m²/s²
0-3 km storm-relative helicity
250 m²/s²
Significant tornado parameter
0.4
Supercell composite
2.7

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 22, 5:35 AM CDTMesoscale DiscussionSPCBeauregard, Calcasieu, De Soto, Sabine, Vernon85 min
Oct 22, 5:55 AM CDTTornado WatchSPCAcadia, Allen, Beauregard, Calcasieu, Caldwell, Cameron and 12 more6 hr
Oct 22, 7:48 AM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 19 more117 min
Oct 22, 10:14 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 10 more91 min
Oct 22, 11:27 AM CDTMesoscale DiscussionSPCAscension, Assumption, Avoyelles, Caldwell, Catahoula, Concordia and 26 more93 min
Oct 22, 3:36 PM CDTMesoscale DiscussionSPCAscension, Assumption, Catahoula, Concordia, East Baton Rouge, East Carroll and 14 more114 min
Oct 22, 4:35 PM CDTTornado WatchSPCJefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 5 more4 hr
Oct 22, 6:26 PM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Carroll, East Feliciana, Livingston and 5 more34 min
Oct 22, 6:55 PM CDTTornado WatchSPCAttala, Bolivar, Carroll, Copiah, Covington, Forrest and 22 more3 hr

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.