Alert archive / Louisiana / Mesoscale Discussions in 2008

Mesoscale Discussion 277

February 21, 200821 parishes in Louisiana; Jefferson County, Orange County, Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 21, 2008, 6:47 AM CST for 21 parishes in Louisiana; Jefferson County, Orange County, Texas. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Feb 21, 2008, 6:47 AM CST (12:47 UTC)
Expired: Feb 21, 2008, 7:45 AM CST
In force: 58 min
Issued by: the Storm Prediction Center

All 23 counties

Acadia Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, St. Mary Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Jefferson County, TX, Orange County, TX

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 0.8 hours before the alert went out and 216 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: 651 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 468 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 182 m²/s²
0-3 km storm-relative helicity: 220 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.4

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, 1:48 AM CST	Mesoscale Discussion	SPC	Assumption, Cameron, Iberia, Jefferson, Lafourche, Plaquemines and 3 more	57 min
Feb 21, 2:51 AM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 14 more	24 min
Feb 21, 3:23 AM CST	Tornado Watch	SPC	Acadia, Ascension, Assumption, Calcasieu, Cameron, Iberia and 15 more	6 hr
Feb 21, 12:56 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 8 more	64 min
Feb 21, 1:41 PM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu and 20 more	7 hr
Feb 21, 4:55 PM CST	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Calcasieu, Cameron, Iberia and 15 more	95 min

Nearby

Mesoscale Discussions in Louisiana, 2008 Mesoscale Discussions in Texas, 2008 Every mesoscale discussion in 2008

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.