Alert archive / Louisiana / Tornado Watches in 2009

Tornado Watch 771

October 22, 200918 parishes in Louisiana; 15 counties in Texas

The Storm Prediction Center issued this tornado watch at Oct 22, 2009, 5:55 AM CDT for 18 parishes in Louisiana; 15 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Oct 22, 2009, 5:55 AM CDT (10:55 UTC)
Expired
Oct 22, 2009, 12:19 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
50 kt
All 33 counties

Acadia Parish, LA, Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, LaSalle Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Chambers County, TX, Galveston County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Tyler County, TX

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
5%
Ten or more severe hail reports
10%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
40%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Oct 22, 6:46 AM CDTFlash Flood WarningHGXBrazoria, Chambers, Fort Bend, Galveston, Harris, Liberty119 min
Oct 22, 7:01 AM CDTTornado WarningHGXChambers, Liberty44 min
Oct 22, 8:56 AM CDTFlash Flood WarningLCHJefferson, Orange3 hr
Oct 22, 9:03 AM CDTFlash Flood WarningLCHHardin, Jasper, Newton, Orange, Tyler3 hr
Oct 22, 9:51 AM CDTFlash Flood WarningLCHBeauregard, Calcasieu, Cameron, Vernon3 hr
Oct 22, 10:04 AM CDTTornado WarningLCHCameron26 min
Oct 22, 10:11 AM CDTTornado WarningLCHCameron34 min
Oct 22, 10:27 AM CDTTornado WarningLCHBeauregard, Calcasieu48 min
Oct 22, 10:48 AM CDTTornado WarningLCHCameron27 min
Oct 22, 10:53 AM CDTTornado WarningLCHCalcasieu, Jefferson Davis37 min
Oct 22, 11:00 AM CDTTornado WarningLCHCameron45 min
Oct 22, 11:09 AM CDTTornado WarningLCHCalcasieu, Cameron, Jefferson Davis35 min
Oct 22, 11:13 AM CDTTornado WarningSHVDe Soto, Red River47 min
Oct 22, 11:34 AM CDTTornado WarningSHVNatchitoches, Sabine41 min
Oct 22, 11:45 AM CDTTornado WarningLCHAcadia, Cameron, Jefferson Davis, Vermilion45 min
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

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 00:00Z, 10.9 hours before the alert went out and 176 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 00:00Z on 2009-10-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 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 00:00Z on 2009-10-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 230 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
20 J/kg
Mixed-layer CIN
-128 J/kg
Mixed-layer LCL
641 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
230 m²/s²
0-3 km storm-relative helicity
192 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
Oct 22, 5:35 AM CDTMesoscale DiscussionSPCBeauregard, Calcasieu, De Soto, Sabine, Vernon85 min
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, 11:58 AM CDTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 40 more7 hr
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 21, 7:11 PM CDTMesoscale DiscussionSPCBell, Blanco, Bosque, Burnet, Comal, Coryell and 12 more94 min

Nearby

Tornado Watches in Louisiana, 2009Tornado Watches in Texas, 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.