Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 619

April 27, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 9:48 AM CDT for 4 states. It was in force for 27 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 9:48 AM CDT (14:48 UTC)
Expired
Apr 27, 2011, 10:15 AM CDT
In force
27 min
Issued by
the Storm Prediction Center
All 42 counties

Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clark County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Lafayette County, AR, Lincoln County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Claiborne County, MS, Issaquena County, MS, Washington County, MS, Harrison County, TX, Marion County, TX, Panola County, TX

The radar

The Shreveport radar (KSHV), 129 km from the middle of the area, began a volume at 14:50 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, 2.8 hours before the alert went out and 120 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 2011-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2193 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 2011-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 473 square meters per square second.1939587897117Sfc1 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
2193 J/kg
Mixed-layer CIN
-26 J/kg
Mixed-layer LCL
541 m above ground
0-6 km bulk shear
85 kt
0-1 km storm-relative helicity
473 m²/s²
0-3 km storm-relative helicity
532 m²/s²
Significant tornado parameter
0.0
Supercell composite
23.4

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 26, 7:59 PM CDTMesoscale DiscussionSPCChicot2 hr
Apr 26, 8:53 PM CDTMesoscale DiscussionSPCCalhoun, Clark, Columbia, Dallas, Grant, Hempstead and 10 more97 min
Apr 26, 9:13 PM CDTMesoscale DiscussionSPCArkansas, Clay, Craighead, Crittenden, Cross, Desha and 21 more62 min
Apr 26, 9:33 PM CDTTornado Watch PDSSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 11 more7 hr
Apr 26, 9:58 PM CDTTornado WatchSPCCraighead, Crittenden, Cross, Greene, Jackson, Lee and 8 more7 hr
Apr 26, 11:33 PM CDTMesoscale DiscussionSPCChicot, Desha, Phillips117 min
Apr 27, 3:29 AM CDTMesoscale DiscussionSPCHempstead, Lafayette, Little River, Miller2 hr
Apr 27, 4:53 AM CDTSevere Thunderstorm WatchSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 19 more5 hr
Apr 27, 6:25 AM CDTMesoscale DiscussionSPCArkansas, Cleburne, Crittenden, Cross, Desha, Faulkner and 15 more65 min
Apr 27, 8:40 AM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Clay, Cleburne and 28 more65 min
Apr 27, 11:02 AM CDTTornado Watch PDSSPCAshley, Chicot8 hr
Apr 27, 12:42 PM CDTSevere Thunderstorm WatchSPCBaxter, Clay, Cleburne, Conway, Craighead, Crittenden and 19 more5 hr
Apr 27, 3:06 PM CDTMesoscale DiscussionSPCClay, Craighead, Greene, Mississippi, Poinsett54 min
Apr 27, 3:29 PM CDTTornado WatchSPCMississippi5 hr
Apr 26, 9:42 PM CDTTornado WatchSPCAvoyelles, Beauregard, Rapides, Vernon7 hr
Apr 27, 2:26 AM CDTTornado WatchSPCCatahoula, Concordia, Franklin, Madison, Tensas6 hr
Apr 27, 10:45 AM CDTMesoscale DiscussionSPCConcordia, East Carroll, Franklin, Madison, Richland, Tensas and 1 more90 min
Apr 27, 1:56 AM CDTMesoscale DiscussionSPCClarke, Copiah, Covington, Jasper, Jefferson Davis, Kemper and 11 more64 min
Apr 27, 8:08 AM CDTTornado WatchSPCAlcorn, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 16 more6 hr
Apr 27, 1:42 PM CDTTornado Watch PDSSPCGreene, Perry, Wayne8 hr
Apr 27, 2:56 PM CDTMesoscale DiscussionSPCAlcorn, Attala, Calhoun, Chickasaw, Choctaw, Clarke and 35 more2 hr
Apr 27, 5:01 PM CDTMesoscale DiscussionSPCAttala, Chickasaw, Choctaw, Clarke, Clay, Covington and 26 more89 min
Apr 27, 6:27 PM CDTMesoscale DiscussionSPCClarke, Clay, Copiah, Covington, Forrest, Jasper and 22 more33 min
Apr 27, 6:42 PM CDTTornado WatchSPCClarke, Covington, Forrest, Jasper, Jefferson Davis, Jones and 13 more3 hr
Apr 26, 7:08 PM CDTMesoscale DiscussionSPCArcher, Baylor, Childress, Clay, Collingsworth, Foard and 13 more97 min

Nearby

Mesoscale Discussions in Louisiana, 2011Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Mississippi, 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; radar from the NEXRAD Level II archive.