Alert archive / Arkansas / Mesoscale Discussions in 2009

Mesoscale Discussion 451

April 12, 200934 counties in Arkansas; 4 parishes in Louisiana; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 12, 2009, 7:13 AM CDT for 34 counties in Arkansas; 4 parishes in Louisiana; 5 counties in Mississippi. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued
Apr 12, 2009, 7:13 AM CDT (12:13 UTC)
Expired
Apr 12, 2009, 8:45 AM CDT
In force
92 min
Issued by
the Storm Prediction Center
All 43 counties

Arkansas County, AR, 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, Faulkner County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Jefferson County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Perry County, AR, Phillips County, AR, Pike County, AR, Polk County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, Sevier County, AR, Union County, AR, Yell County, AR, East Carroll Parish, LA, Morehouse Parish, LA, Union Parish, LA, West Carroll Parish, LA, Bolivar County, MS, Coahoma County, MS, Issaquena County, MS, Sunflower County, MS, Washington County, MS

The radar

The Little Rock radar (KLZK), 100 km from the middle of the area, began a volume at 12:16 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, 0.2 hours before the alert went out and 197 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 2009-04-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2009-04-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 229 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
764 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
229 m²/s²
0-3 km storm-relative helicity
311 m²/s²
Significant tornado parameter
0.0
Supercell composite
7.8

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 12, 7:44 AM CDTSevere Thunderstorm WatchSPCArkansas, Bradley, Calhoun, Clark, Cleveland, Conway and 20 more6 hr
Apr 12, 9:30 AM CDTSevere Thunderstorm WatchSPCColumbia, Hempstead, Lafayette, Miller, Nevada, Union7 hr
Apr 12, 12:00 PM CDTMesoscale DiscussionSPCArkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 10 more90 min
Apr 12, 5:49 PM CDTMesoscale DiscussionSPCChicot86 min
Apr 12, 7:39 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 11 more66 min
Apr 12, 7:58 AM CDTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more8 hr
Apr 12, 9:19 AM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Caldwell, De Soto, Jackson and 10 more56 min
Apr 12, 10:53 AM CDTMesoscale DiscussionSPCAcadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 2 more2 hr
Apr 12, 1:02 PM CDTMesoscale DiscussionSPCAscension, Assumption, Concordia, East Baton Rouge, East Feliciana, Franklin and 14 more88 min
Apr 12, 1:53 PM CDTTornado WatchSPCAscension, Assumption, Catahoula, Concordia, East Baton Rouge, East Carroll and 26 more7 hr

Nearby

Mesoscale Discussions in Arkansas, 2009Mesoscale Discussions in Mississippi, 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.