Alert archive / Texas / Mesoscale Discussions in 2009

Mesoscale Discussion 678

May 2, 200913 counties in Arkansas; 11 parishes in Louisiana; 21 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 2, 2009, 7:38 PM CDT for 13 counties in Arkansas; 11 parishes in Louisiana; 21 counties in Texas. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
May 2, 2009, 7:38 PM CDT (00:38 UTC)
Expired
May 2, 2009, 9:15 PM CDT
In force
97 min
Issued by
the Storm Prediction Center
All 45 counties

Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Columbia County, AR, Dallas County, AR, Drew County, AR, Hempstead County, AR, Lafayette County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Bowie County, TX, Camp County, TX, Cass County, TX, Dallas County, TX, Ellis County, TX, Franklin County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Hopkins County, TX, Hunt County, TX, Kaufman County, TX, Marion County, TX, Morris County, TX, Rains County, TX, Rockwall County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 90 km from the middle of the area, began a volume at 00:41 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 00:00Z, 0.6 hours before the alert went out and 94 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 2009-05-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1069 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 2009-05-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 177 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
1069 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
1182 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
177 m²/s²
0-3 km storm-relative helicity
230 m²/s²
Significant tornado parameter
0.9
Supercell composite
10.6

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
May 2, 9:59 PM CDTMesoscale DiscussionSPCBradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 9 more3 hr
May 2, 10:40 PM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Chicot, Columbia, Drew and 7 more2 hr
May 2, 11:43 PM CDTSevere Thunderstorm WatchSPCColumbia, Hempstead, Howard, Lafayette, Little River, Miller and 3 more5 hr
May 3, 2:39 AM CDTMesoscale DiscussionSPCAshley, Bradley, Calhoun, Chicot, Drew, Union2 hr
May 3, 5:12 AM CDTSevere Thunderstorm WatchSPCBeauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 14 more7 hr
May 3, 6:54 AM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Bienville, Caddo and 25 more2 hr
May 3, 7:44 AM CDTSevere Thunderstorm WatchSPCAcadia, Allen, Ascension, Avoyelles, Calcasieu, Catahoula and 20 more8 hr
May 3, 9:24 AM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 30 more66 min
May 3, 11:35 AM CDTSevere Thunderstorm WatchSPCSaint Tammany5 hr
May 2, 8:04 PM CDTMesoscale DiscussionSPCBorden, Callahan, Coleman, Comanche, Dawson, Eastland and 21 more86 min
May 3, 3:02 AM CDTMesoscale DiscussionSPCAnderson, Bell, Bosque, Brown, Burnet, Collin and 28 more118 min

Nearby

Mesoscale Discussions in Texas, 2009Mesoscale Discussions in Arkansas, 2009Mesoscale Discussions in Louisiana, 2009Every mesoscale discussion 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; radar from the NEXRAD Level II archive.