Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 2141

December 9, 20128 counties in Arkansas; 4 parishes in Louisiana; 37 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2012, 5:04 PM CST for 8 counties in Arkansas; 4 parishes in Louisiana; 37 counties in Texas. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued
Dec 9, 2012, 5:04 PM CST (23:04 UTC)
Expired
Dec 9, 2012, 7:00 PM CST
In force
116 min
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 49 counties

Clark County, AR, Columbia County, AR, Dallas County, AR, Hempstead County, AR, Lafayette County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Bossier Parish, LA, Caddo Parish, LA, De Soto Parish, LA, Webster Parish, LA, Angelina County, TX, Austin County, TX, Bastrop County, TX, Brazos County, TX, Burleson County, TX, Caldwell County, TX, Cass County, TX, Cherokee County, TX, Colorado County, TX, DeWitt County, TX, Fayette County, TX, Gonzales County, TX, Gregg County, TX, Grimes County, TX, Guadalupe County, TX, Harrison County, TX, Houston County, TX, Lavaca County, TX, Lee County, TX, Leon County, TX, Madison County, TX, Marion County, TX, Montgomery County, TX, Nacogdoches County, TX, Panola County, TX, Polk County, TX, Rusk County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Travis County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wilson County, TX

The radar

The Shreveport radar (KSHV), 155 km from the middle of the area, began a volume at 23:07 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 11.1 hours before the alert went out and 163 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 2012-12-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 402 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 2012-12-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 250 square meters per square second.1939587897Sfc1 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
402 J/kg
Mixed-layer CIN
-42 J/kg
Mixed-layer LCL
568 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
250 m²/s²
0-3 km storm-relative helicity
241 m²/s²
Significant tornado parameter
0.3
Supercell composite
3.0

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 8, 10:18 PM CSTMesoscale DiscussionSPCConway, Garland, Logan, Montgomery, Perry, Polk and 2 more117 min
Dec 9, 1:46 AM CSTMesoscale DiscussionSPCCrittenden, Cross, Garland, Lee, Lonoke, Monroe and 6 more2 hr
Dec 9, 12:38 PM CSTMesoscale DiscussionSPCArkansas, Clark, Clay, Cleburne, Cleveland, Conway and 41 more2 hr
Dec 9, 2:10 PM CSTTornado WatchSPCArkansas, Clay, Cleburne, Conway, Craighead, Crittenden and 29 more9 hr
Dec 9, 5:47 PM CSTSevere Thunderstorm WatchSPCAshley, Bradley, Calhoun, Chicot, Clark, Cleveland and 9 more6 hr
Dec 9, 5:54 PM CSTMesoscale DiscussionSPCArkansas, Clay, Cleburne, Craighead, Crittenden, Cross and 20 more96 min
Dec 9, 1:32 PM CSTMesoscale DiscussionSPCAnderson, Bell, Camp, Cherokee, Falls, Franklin and 16 more58 min

Nearby

Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Louisiana, 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; radar from the NEXRAD Level II archive.