Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 440

April 3, 20127 counties in Arkansas; 6 parishes in Louisiana; 30 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 3, 2012, 6:53 PM CDT for 7 counties in Arkansas; 6 parishes in Louisiana; 30 counties in Texas. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Apr 3, 2012, 6:53 PM CDT (23:53 UTC)
Expired
Apr 3, 2012, 8:00 PM CDT
In force
67 min
Issued by
the Storm Prediction Center
All 43 counties

Columbia County, AR, Hempstead County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Red River Parish, LA, Webster Parish, LA, Anderson County, TX, Angelina County, TX, Bastrop County, TX, Bowie County, TX, Brazos County, TX, Burleson County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Freestone County, TX, Gregg County, TX, Grimes County, TX, Harrison County, TX, Houston County, TX, Lee County, TX, Leon County, TX, Madison County, TX, Marion County, TX, Milam County, TX, Morris County, TX, Nacogdoches County, TX, Panola County, TX, Robertson County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Trinity County, TX, Upshur County, TX, Walker County, TX, Washington County, TX

The radar

The Shreveport radar (KSHV), 104 km from the middle of the area, began a volume at 23:54 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, 11.9 hours before the alert went out and 113 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 2012-04-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1328 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 2012-04-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 148 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
1328 J/kg
Mixed-layer CIN
-64 J/kg
Mixed-layer LCL
475 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
148 m²/s²
0-3 km storm-relative helicity
286 m²/s²
Significant tornado parameter
0.0
Supercell composite
8.5

Open this sounding in Storm Lab

The text

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

315 
ACUS11 KWNS 032353
SWOMCD
SPC MCD 032353 
ARZ000-LAZ000-TXZ000-OKZ000-040100-

MESOSCALE DISCUSSION 0440
NWS STORM PREDICTION CENTER NORMAN OK
0653 PM CDT TUE APR 03 2012

AREAS AFFECTED...ARKLATEX TO E-CNTRL TX

CONCERNING...TORNADO WATCH 133...135...

VALID 032353Z - 040100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 133...135...CONTINUES.

WITH WW 133 SCHEDULED TO EXPIRE AT 01Z AND THE TORNADO THREAT LIKELY
DIMINISHING...PORTIONS OF WW 133/135 MAY BE REDEFINED WITH A
REPLACEMENT WW PRIOR TO 01Z.

NRN PORTION OF QLCS HAD RECENTLY ACCELERATED AND CONSOLIDATED WITH
SEMI-DISCRETE SUPERCELLS THAT HAD BEEN PREVALENT ALONG A
W/E-ORIENTED OUTFLOW OVER FAR NERN TX. A BRIEF TORNADO WILL REMAIN
POSSIBLE WITHIN THIS AREA...GIVEN RELATIVELY STRONGER LOW-LEVEL
SHEAR. BUT THE PROGRESSIVE/UNDERCUTTING NATURE OF THE QLCS SUGGESTS
TORNADIC POTENTIAL SHOULD WEAKEN FURTHER COMPARED TO A FEW HOURS
AGO...TRANSITIONING TO MORE OF A DAMAGING WIND THREAT.

FARTHER SW INTO E-CNTRL TX...BASED ON RADAR/SURFACE OBSERVATIONS IT
APPEARS THE OUTFLOW HAS SURGED 10-25 MILES OUT AHEAD OF THE SLOWER
MOVING PORTION OF THE QLCS. STILL...A RISK FOR EMBEDDED MARGINALLY
SEVERE HAIL AND LOCALIZED DOWNBURSTS SHOULD PERSIST FOR THE NEXT
SEVERAL HOURS GIVEN A MODERATELY STRONG COMBINATION OF BUOYANCY AND
DEEP-LAYER SHEAR.

..GRAMS.. 04/03/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LZK...SHV...HGX...FWD...EWX...

LAT...LON   31529647 32549544 33039498 33879433 33959400 33979349
            33859303 33619282 33349281 32969274 32149324 31039467
            30579551 30189625 29989687 30059730 30219745 31529647

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 3, 1:42 PM CDTMesoscale DiscussionSPCChicot93 min
Apr 3, 2:22 PM CDTSevere Thunderstorm WatchSPCColumbia, Hempstead, Lafayette, Nevada, Union8 hr
Apr 3, 2:36 PM CDTTornado WatchSPCHoward, Little River, Miller, Sevier7 hr
Apr 3, 3:05 PM CDTMesoscale DiscussionSPCHempstead, Howard, Little River, Montgomery, Nevada, Pike and 2 more85 min
Apr 3, 3:43 PM CDTSevere Thunderstorm WatchSPCBoone, Bradley, Calhoun, Clark, Crawford, Dallas and 16 more6 hr
Apr 3, 5:00 PM CDTMesoscale DiscussionSPCLittle River, Miller60 min
Apr 3, 5:24 PM CDTMesoscale DiscussionSPCAshley, Chicot, Union66 min
Apr 2, 10:10 PM CDTMesoscale DiscussionSPCIberia, St. Mary3 hr
Apr 3, 1:46 PM CDTMesoscale DiscussionSPCCaddo, De Soto89 min
Apr 2, 7:17 PM CDTMesoscale DiscussionSPCHansford, Hemphill, Hutchinson, Lipscomb, Ochiltree, Roberts58 min
Apr 2, 9:12 PM CDTMesoscale DiscussionSPCArcher, Baylor, Clay, Hardeman, Haskell, Hemphill and 12 more63 min
Apr 2, 10:51 PM CDTSevere Thunderstorm WatchSPCArcher, Baylor, Clay, Jack, Montague, Wichita and 2 more5 hr
Apr 2, 11:45 PM CDTMesoscale DiscussionSPCBrown, Callahan, Coleman, Comanche, Concho, Eastland and 17 more2 hr
Apr 3, 1:14 AM CDTMesoscale DiscussionSPCArcher, Baylor, Callahan, Clay, Jack, Montague and 7 more2 hr
Apr 3, 3:32 AM CDTMesoscale DiscussionSPCArcher, Baylor, Borden, Brown, Callahan, Clay and 24 more88 min
Apr 3, 8:36 AM CDTMesoscale DiscussionSPCArcher, Bell, Blanco, Bosque, Brown, Burnet and 40 more84 min
Apr 3, 9:18 AM CDTSevere Thunderstorm WatchSPCBosque, Clay, Collin, Comanche, Cooke, Coryell and 33 more8 hr
Apr 3, 11:47 AM CDTMesoscale DiscussionSPCBosque, Collin, Cooke, Coryell, Dallas, Delta and 32 more118 min
Apr 3, 12:08 PM CDTTornado WatchSPCAnderson, Bell, Bosque, Collin, Coryell, Dallas and 30 more9 hr
Apr 3, 1:12 PM CDTMesoscale DiscussionSPCBosque, Collin, Dallas, Denton, Ellis, Erath and 16 more93 min
Apr 3, 2:21 PM CDTMesoscale DiscussionSPCLamar, Montague84 min
Apr 3, 4:38 PM CDTMesoscale DiscussionSPCAustin, Bastrop, Brazos, Burleson, Caldwell, Fayette and 10 more67 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.