Alert archive / Louisiana / Mesoscale Discussions in 2013

Mesoscale Discussion 191

February 21, 201320 parishes in Louisiana; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 21, 2013, 1:22 PM CST for 20 parishes in Louisiana; 5 counties in Mississippi. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: Feb 21, 2013, 1:22 PM CST (19:22 UTC)
Expired: Feb 21, 2013, 3:15 PM CST
In force: 113 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 25 counties

Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Franklin County, MS, Pike County, MS, Wilkinson County, MS

The watches that followed

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

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 7.4 hours before the alert went out and 204 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: 13 J/kg
Mixed-layer CIN: -343 J/kg
Mixed-layer LCL: 461 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: 509 m²/s²
0-3 km storm-relative helicity: 644 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 7.8

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
Feb 21, 1:37 PM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 10 more	5 hr
Feb 21, 3:15 PM CST	Mesoscale Discussion	SPC	Allen, Avoyelles, Beauregard, Catahoula, Evangeline, Grant and 4 more	90 min
Feb 21, 3:48 PM CST	Mesoscale Discussion	SPC	Concordia, Franklin, Saint Helena, Tensas, Washington	57 min
Feb 21, 5:20 PM CST	Tornado Watch	SPC	Adams, Amite, Claiborne, Clarke, Copiah, Covington and 15 more	7 hr

Nearby

Mesoscale Discussions in Louisiana, 2013 Mesoscale Discussions in Mississippi, 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.