Alert archive / Louisiana / Mesoscale Discussions in 2007

Mesoscale Discussion 2154

November 21, 20074 states

The Storm Prediction Center issued this mesoscale discussion at Nov 21, 2007, 5:10 PM CST for 4 states. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Nov 21, 2007, 5:10 PM CST (23:10 UTC)
Expired: Nov 21, 2007, 6:15 PM CST
In force: 65 min
Issued by: the Storm Prediction Center

All 99 counties

Ashley County, AR, Chicot County, AR, Columbia County, AR, Union County, AR, Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Cameron Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, De Soto Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Livingston Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Union Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Washington Parish, LA, Webster Parish, LA, West Baton Rouge Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Hinds County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pike County, MS, Rankin County, MS, Sharkey County, MS, Simpson County, MS, Walthall County, MS, Warren County, MS, Washington County, MS, Wilkinson County, MS, Yazoo County, MS, Angelina County, TX, Hardin 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

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 736Nov 21, 5:30 PM CST

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 11.2 hours before the alert went out and 120 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: 1033 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 575 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 112 m²/s²
0-3 km storm-relative helicity: 138 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

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, 11:17 AM CST	Mesoscale Discussion	SPC	Arkansas, Ashley, Baxter, Bradley, Calhoun, Chicot and 58 more	118 min
Nov 21, 12:47 PM CST	Tornado Watch	SPC	Arkansas, Bradley, Calhoun, Clark, Clay, Cleburne and 43 more	6 hr
Nov 21, 2:29 PM CST	Severe Thunderstorm Watch	SPC	Ashley, Chicot, Columbia, Lafayette, Miller, Union	8 hr
Nov 21, 3:18 PM CST	Mesoscale Discussion	SPC	Arkansas, Clark, Clay, Cleburne, Cleveland, Conway and 34 more	87 min
Nov 21, 12:24 PM CST	Mesoscale Discussion	SPC	Ascension, East Baton Rouge, East Feliciana, Iberville, Lafayette, Livingston and 13 more	2 hr
Nov 21, 1:32 PM CST	Mesoscale Discussion	SPC	Beauregard, Bienville, Bossier, Caddo, Claiborne, De Soto and 9 more	118 min
Nov 21, 5:29 PM CST	Severe Thunderstorm Watch	SPC	Acadia, Allen, Ascension, Avoyelles, Calcasieu, Catahoula and 19 more	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2007 Mesoscale Discussions in Mississippi, 2007 Mesoscale Discussions in Texas, 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.