Alert archive / Texas / Mesoscale Discussions in 2011

Mesoscale Discussion 2351

November 21, 201112 counties in Arkansas; 24 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Nov 21, 2011, 10:45 PM CST for 12 counties in Arkansas; 24 counties in Texas. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Nov 21, 2011, 10:45 PM CST (04:45 UTC)
Expired: Nov 22, 2011, 12:15 AM CST
In force: 90 min
Issued by: the Storm Prediction Center

All 36 counties

Clark County, AR, Garland County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Little River County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Pike County, AR, Polk County, AR, Sevier County, AR, Anderson County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Falls County, TX, Franklin County, TX, Freestone County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Leon County, TX, Limestone County, TX, Marion County, TX, McLennan County, TX, Morris County, TX, Navarro County, TX, Robertson County, TX, Rusk County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 116 km from the middle of the area, began a volume at 04:44 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 nearest sounding before it

Shreveport, LA (KSHV), launched 00:00Z, 4.8 hours before the alert went out and 121 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: 485 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 1180 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 131 m²/s²
0-3 km storm-relative helicity: 246 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.0

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.

Issued	Product	Office	Counties	Lasted
Nov 21, 8:16 PM CST	Mesoscale Discussion	SPC	Clark, Dallas, Garland, Hempstead, Hot Spring, Howard and 7 more	89 min
Nov 21, 8:36 PM CST	Tornado Watch	SPC	Arkansas, Clark, Cleveland, Dallas, Garland, Grant and 17 more	5 hr
Nov 22, 1:46 AM CST	Mesoscale Discussion	SPC	Arkansas, Clark, Cleveland, Dallas, Garland, Grant and 17 more	59 min

Nearby

Mesoscale Discussions in Texas, 2011 Mesoscale Discussions in Arkansas, 2011 Every 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.