Alert archive / Texas / Mesoscale Discussions in 2013

Mesoscale Discussion 760

May 21, 20138 counties in Arkansas; 10 parishes in Louisiana; 17 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 21, 2013, 5:54 PM CDT for 8 counties in Arkansas; 10 parishes in Louisiana; 17 counties in Texas. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: May 21, 2013, 5:54 PM CDT (22:54 UTC)
Expired: May 21, 2013, 7:00 PM CDT
In force: 66 min
Issued by: the Storm Prediction Center

All 35 counties

Calhoun County, AR, Columbia County, AR, Hempstead County, AR, Lafayette County, AR, Miller County, AR, Nevada County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Red River Parish, LA, Union Parish, LA, Webster Parish, LA, Anderson County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Henderson County, TX, Marion County, TX, Morris County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 41 km from the middle of the area, began a volume at 22:54 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 12:00Z, 10.9 hours before the alert went out and 46 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: 2465 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 475 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 162 m²/s²
0-3 km storm-relative helicity: 167 m²/s²
Significant tornado parameter: 1.5
Supercell composite: 8.3

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
May 20, 7:39 PM CDT	Tornado Watch	SPC	Baxter, Benton, Boone, Carroll, Cleburne, Conway and 26 more	6 hr
May 21, 12:03 AM CDT	Severe Thunderstorm Watch	SPC	Crawford, Franklin, Sebastian	7 hr
May 21, 12:50 AM CDT	Severe Thunderstorm Watch	SPC	Clay, Craighead, Crittenden, Cross, Greene, Lawrence and 5 more	3 hr
May 21, 4:20 AM CDT	Mesoscale Discussion	SPC	Crawford, Franklin, Sebastian	55 min
May 21, 7:47 AM CDT	Mesoscale Discussion	SPC	Crittenden, Cross, Lee, Mississippi, Phillips, Poinsett and 1 more	58 min
May 21, 1:35 PM CDT	Mesoscale Discussion	SPC	Lafayette, Miller	115 min
May 21, 1:50 PM CDT	Tornado Watch	SPC	Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 13 more	8 hr
May 21, 2:42 PM CDT	Mesoscale Discussion	SPC	Clay, Craighead, Crittenden, Cross, Greene, Jackson and 8 more	63 min
May 21, 3:00 PM CDT	Tornado Watch	SPC	Arkansas, Ashley, Chicot, Clay, Craighead, Crittenden and 11 more	7 hr
May 21, 3:18 PM CDT	Mesoscale Discussion	SPC	Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 11 more	87 min
May 21, 6:23 PM CDT	Mesoscale Discussion	SPC	Chicot, Desha	67 min
May 20, 8:45 PM CDT	Mesoscale Discussion	SPC	Bosque, Brown, Burnet, Callahan, Clay, Coleman and 37 more	60 min
May 21, 8:12 AM CDT	Mesoscale Discussion	SPC	Archer, Clay, Collin, Cooke, Delta, Denton and 9 more	93 min
May 21, 10:09 AM CDT	Mesoscale Discussion	SPC	Anderson, Bosque, Bowie, Brown, Callahan, Camp and 57 more	96 min
May 21, 10:26 AM CDT	Tornado Watch	SPC	Anderson, Archer, Baylor, Bell, Bosque, Brown and 58 more	10 hr
May 21, 10:45 AM CDT	Severe Thunderstorm Watch	SPC	Foard, Hardeman, Knox, Wichita, Wilbarger	6 hr
May 21, 1:19 PM CDT	Mesoscale Discussion	SPC	Anderson, Bosque, Brown, Collin, Comanche, Concho and 38 more	116 min
May 21, 4:55 PM CDT	Mesoscale Discussion	SPC	Brazos, Burleson, Houston, Madison, Trinity, Walker	95 min
May 21, 6:55 PM CDT	Severe Thunderstorm Watch	SPC	Brazos, Burleson, Grimes, Hardin, Houston, Jasper and 9 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2013 Mesoscale Discussions in Louisiana, 2013 Mesoscale Discussions in Arkansas, 2013 Every mesoscale discussion in 2013

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.