Alert archive / Arkansas / Mesoscale Discussions in 2007

Mesoscale Discussion 451

April 11, 200720 counties in Arkansas; Morehouse Parish, Union Parish, West Carroll Parish, Louisiana; 10 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2007, 2:19 AM CDT for 20 counties in Arkansas; Morehouse Parish, Union Parish, West Carroll Parish, Louisiana; 10 counties in Mississippi. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Apr 11, 2007, 2:19 AM CDT (07:19 UTC)
Expired: Apr 11, 2007, 4:15 AM CDT
In force: 116 min
Issued by: the Storm Prediction Center

All 33 counties

Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Jefferson County, AR, Lee County, AR, Lincoln County, AR, Monroe County, AR, Nevada County, AR, Ouachita County, AR, Phillips County, AR, Prairie County, AR, Union County, AR, Morehouse Parish, LA, Union Parish, LA, West Carroll Parish, LA, Bolivar County, MS, Coahoma County, MS, Humphreys County, MS, Issaquena County, MS, Leflore County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Washington County, MS

The radar

The Little Rock radar (KLZK), 143 km from the middle of the area, began a volume at 07:20 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.

Severe Thunderstorm Watch 123Apr 11, 2:55 AM CDT

The nearest sounding before it

Shreveport, LA (KSHV), launched 00:00Z, 7.3 hours before the alert went out and 218 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 200 J/kg
Mixed-layer CIN: -180 J/kg
Mixed-layer LCL: 623 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 417 m²/s²
0-3 km storm-relative helicity: 552 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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.

Issued	Product	Office	Counties	Lasted
Apr 10, 9:19 PM CDT	Mesoscale Discussion	SPC	Howard, Little River, Polk, Scott, Sebastian, Sevier	56 min
Apr 10, 11:24 PM CDT	Mesoscale Discussion	SPC	Arkansas, Ashley, Bradley, Calhoun, Clark, Cleburne and 42 more	96 min
Apr 10, 11:45 PM CDT	Severe Thunderstorm Watch	SPC	Arkansas, Bradley, Calhoun, Clark, Cleveland, Dallas and 23 more	4 hr
Apr 11, 2:56 AM CDT	Severe Thunderstorm Watch	SPC	Ashley, Chicot, Lee, Phillips	5 hr
Apr 11, 4:36 AM CDT	Mesoscale Discussion	SPC	East Carroll, Madison, Morehouse, Richland, West Carroll	114 min
Apr 11, 7:30 AM CDT	Mesoscale Discussion	SPC	Attala, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 9 more	60 min
Apr 11, 12:16 PM CDT	Mesoscale Discussion	SPC	Alcorn, Attala, Chickasaw, Choctaw, Clarke, Clay and 19 more	59 min
Apr 11, 1:42 PM CDT	Tornado Watch	SPC	Clarke, Jasper, Kemper, Lauderdale, Lowndes, Neshoba and 3 more	5 hr

Nearby

Mesoscale Discussions in Arkansas, 2007 Mesoscale Discussions in Mississippi, 2007 Mesoscale Discussions in Louisiana, 2007 Every mesoscale discussion in 2007

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.