Alert archive / Louisiana / Mesoscale Discussions in 2013

Mesoscale Discussion 2099

December 21, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Dec 21, 2013, 12:30 PM CST for 4 states. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Dec 21, 2013, 12:30 PM CST (18:30 UTC)
Expired: Dec 21, 2013, 1:30 PM CST
In force: 60 min
Issued by: the Storm Prediction Center

All 59 counties

Ashley County, AR, Chicot County, AR, Columbia County, AR, Lafayette County, AR, Union County, AR, Allen Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Washington County, MS, Angelina County, TX, Austin County, TX, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Orange County, TX, Panola County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Wharton County, TX

The radar

The Lake Charles radar (KLCH), 137 km from the middle of the area, began a volume at 18:33 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

Lake Charles Mun, LA (KLCH), launched 12:00Z, 6.5 hours before the alert went out and 139 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: 509 J/kg
Mixed-layer CIN: -112 J/kg
Mixed-layer LCL: 558 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 54 m²/s²
0-3 km storm-relative helicity: 165 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 0.7

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
Dec 20, 6:44 PM CST	Mesoscale Discussion	SPC	Clark, Dallas, Garland, Grant, Hempstead, Hot Spring and 11 more	91 min
Dec 20, 8:18 PM CST	Mesoscale Discussion	SPC	Benton	6 hr
Dec 20, 10:42 PM CST	Mesoscale Discussion	SPC	Miller	2 hr
Dec 21, 2:31 AM CST	Mesoscale Discussion	SPC	Clark, Clay, Cleburne, Columbia, Conway, Craighead and 30 more	2 hr
Dec 21, 7:57 AM CST	Mesoscale Discussion	SPC	Ashley, Bradley, Calhoun, Cleveland, Columbia, Drew and 3 more	63 min
Dec 21, 9:46 AM CST	Tornado Watch	SPC	Ashley, Chicot, Columbia, Lafayette, Union	8 hr
Dec 21, 10:45 AM CST	Mesoscale Discussion	SPC	Arkansas, Bradley, Calhoun, Cleveland, Crittenden, Desha and 8 more	60 min
Dec 21, 12:01 PM CST	Tornado Watch	SPC	Arkansas, Bradley, Calhoun, Cleveland, Crittenden, Dallas and 10 more	8 hr
Dec 21, 2:50 PM CST	Mesoscale Discussion	SPC	Arkansas, Bradley, Crittenden, Cross, Desha, Drew and 6 more	55 min
Dec 21, 5:06 PM CST	Mesoscale Discussion	SPC	Ascension, Concordia, East Baton Rouge, East Carroll, East Feliciana, Iberville and 9 more	84 min
Dec 21, 5:22 PM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Avoyelles, Catahoula, Concordia and 21 more	7 hr
Dec 21, 5:46 PM CST	Tornado Watch	SPC	Alcorn, Benton, Calhoun, Chickasaw, Coahoma, DeSoto and 16 more	6 hr
Dec 21, 6:20 AM CST	Mesoscale Discussion	SPC	Bell, Blanco, Bosque, Brown, Burnet, Coleman and 31 more	115 min
Dec 21, 9:53 AM CST	Mesoscale Discussion	SPC	Atascosa, Bastrop, Bee, Bexar, Caldwell, DeWitt and 11 more	67 min
Dec 21, 10:29 AM CST	Severe Thunderstorm Watch	SPC	Aransas, Atascosa, Bastrop, Bee, Caldwell, Calhoun and 14 more	3 hr

Nearby

Mesoscale Discussions in Louisiana, 2013 Mesoscale Discussions in Texas, 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.