Alert archive / Louisiana / Mesoscale Discussions in 2012

Mesoscale Discussion 2130

December 4, 201226 parishes in Louisiana; 14 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 4, 2012, 11:09 AM CST for 26 parishes in Louisiana; 14 counties in Texas. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
Dec 4, 2012, 11:09 AM CST (17:09 UTC)
Expired
Dec 4, 2012, 12:45 PM CST
In force
96 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 40 counties

Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, De Soto Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Chambers County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty 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

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 5.2 hours before the alert went out and 166 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 2012-12-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 879 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 2012-12-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 202 square meters per square second.193958Sfc1 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
879 J/kg
Mixed-layer CIN
-21 J/kg
Mixed-layer LCL
565 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
202 m²/s²
0-3 km storm-relative helicity
231 m²/s²
Significant tornado parameter
0.6
Supercell composite
5.2

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
Dec 4, 1:08 PM CSTMesoscale DiscussionSPCAransas, Austin, Bee, Brazoria, Brooks, Calhoun and 20 more2 hr

Nearby

Mesoscale Discussions in Louisiana, 2012Mesoscale Discussions in Texas, 2012Every mesoscale discussion in 2012

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.