Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 344

April 4, 201118 parishes in Louisiana; 17 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 4, 2011, 11:20 AM CDT for 18 parishes in Louisiana; 17 counties in Texas. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Apr 4, 2011, 11:20 AM CDT (16:20 UTC)
Expired
Apr 4, 2011, 1:15 PM CDT
In force
115 min
Issued by
the Storm Prediction Center
All 35 counties

Beauregard Parish, LA, Bienville Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Chambers County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Tyler County, TX, Waller County, TX

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 4.3 hours before the alert went out and 136 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 2011-04-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1653 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 2011-04-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 196 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
1653 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
738 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
196 m²/s²
0-3 km storm-relative helicity
292 m²/s²
Significant tornado parameter
1.6
Supercell composite
8.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 4, 7:44 AM CDTSevere Thunderstorm WatchSPCBienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more8 hr
Apr 4, 10:25 AM CDTMesoscale DiscussionSPCEast Carroll, Morehouse, West Carroll2 hr
Apr 4, 10:53 AM CDTTornado WatchSPCAcadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 32 more7 hr
Apr 4, 2:52 PM CDTMesoscale DiscussionSPCAvoyelles, Caldwell, Catahoula, Concordia, Franklin, LaSalle and 4 more113 min
Apr 4, 4:28 PM CDTMesoscale DiscussionSPCJefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 2 more62 min
Apr 4, 5:28 PM CDTTornado WatchSPCAscension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 18 more7 hr
Apr 4, 6:50 PM CDTMesoscale DiscussionSPCAscension, Assumption, Iberia, Jefferson, Lafourche, Livingston and 10 more85 min
Apr 4, 3:00 AM CDTMesoscale DiscussionSPCBosque, Bowie, Brown, Callahan, Camp, Cass and 42 more3 hr
Apr 4, 3:44 AM CDTSevere Thunderstorm WatchSPCBowie, Camp, Cass, Cherokee, Franklin, Gregg and 12 more7 hr
Apr 4, 5:48 AM CDTMesoscale DiscussionSPCAnderson, Bosque, Bowie, Camp, Cass, Collin and 33 more117 min

Nearby

Mesoscale Discussions in Louisiana, 2011Mesoscale Discussions in Texas, 2011Every mesoscale discussion in 2011

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.