Alert archive / Arkansas / Mesoscale Discussions in 2007

Mesoscale Discussion 2149

November 21, 20077 states

The Storm Prediction Center issued this mesoscale discussion at Nov 21, 2007, 11:17 AM CST for 7 states. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued
Nov 21, 2007, 11:17 AM CST (17:17 UTC)
Expired
Nov 21, 2007, 1:15 PM CST
In force
118 min
Issued by
the Storm Prediction Center
All 96 counties

Arkansas County, AR, Ashley County, AR, Baxter County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clark County, AR, Clay County, AR, Cleburne County, AR, Cleveland County, AR, Columbia County, AR, Conway County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Faulkner County, AR, Fulton County, AR, Garland County, AR, Grant County, AR, Greene County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Jefferson County, AR, Lafayette County, AR, Lawrence County, AR, Lee County, AR, Lincoln County, AR, Little River County, AR, Logan County, AR, Lonoke County, AR, Miller County, AR, Mississippi County, AR, Monroe County, AR, Montgomery County, AR, Nevada County, AR, Ouachita County, AR, Perry County, AR, Phillips County, AR, Pike County, AR, Poinsett County, AR, Polk County, AR, Pope County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sevier County, AR, Sharp County, AR, St. Francis County, AR, Stone County, AR, Union County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR, Yell County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Union Parish, LA, Webster Parish, LA, Butler County, MO, Dunklin County, MO, Oregon County, MO, Pemiscot County, MO, Ripley County, MO, Bolivar County, MS, Coahoma County, MS, DeSoto County, MS, Panola County, MS, Quitman County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tunica County, MS, McCurtain County, OK, Lauderdale County, TN, Shelby County, TN, Tipton County, TN, Bowie County, TX, Cass County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Red River County, TX, Titus County, TX

The radar

The Little Rock radar (KLZK), 64 km from the middle of the area, began a volume at 17:17 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

Little Rock, AR (KLZK), launched 12:00Z, 5.3 hours before the alert went out and 201 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, Little Rock, AR at 12:00Z on 2007-11-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 91 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, Little Rock, AR at 12:00Z on 2007-11-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 108 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
91 J/kg
Mixed-layer CIN
-84 J/kg
Mixed-layer LCL
805 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
108 m²/s²
0-3 km storm-relative helicity
93 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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
Nov 21, 12:47 PM CSTTornado WatchSPCArkansas, Bradley, Calhoun, Clark, Clay, Cleburne and 43 more6 hr
Nov 21, 2:29 PM CSTSevere Thunderstorm WatchSPCAshley, Chicot, Columbia, Lafayette, Miller, Union8 hr
Nov 21, 3:18 PM CSTMesoscale DiscussionSPCArkansas, Clark, Clay, Cleburne, Cleveland, Conway and 34 more87 min
Nov 21, 5:10 PM CSTMesoscale DiscussionSPCAshley, Chicot, Columbia, Union65 min
Nov 21, 12:24 PM CSTMesoscale DiscussionSPCAscension, East Baton Rouge, East Feliciana, Iberville, Lafayette, Livingston and 13 more2 hr
Nov 21, 1:32 PM CSTMesoscale DiscussionSPCBeauregard, Bienville, Bossier, Caddo, Claiborne, De Soto and 9 more118 min
Nov 21, 5:29 PM CSTSevere Thunderstorm WatchSPCAcadia, Allen, Ascension, Avoyelles, Calcasieu, Catahoula and 19 more6 hr
Nov 21, 12:28 PM CSTMesoscale DiscussionSPCAtchison, Gentry, Harrison, Holt, Mercer, Nodaway and 3 more5 hr

Nearby

Mesoscale Discussions in Arkansas, 2007Mesoscale Discussions in Mississippi, 2007Mesoscale Discussions in Louisiana, 2007Every 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.