Alert archive / Louisiana / Mesoscale Discussions in 2008

Mesoscale Discussion 274

February 21, 20089 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Feb 21, 2008, 1:48 AM CST for 9 parishes in Louisiana. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Feb 21, 2008, 1:48 AM CST (07:48 UTC)
Expired: Feb 21, 2008, 2:45 AM CST
In force: 57 min
Issued by: the Storm Prediction Center

Counties Assumption Parish, LA, Cameron Parish, LA, Iberia Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Plaquemines Parish, LA, St. Mary Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA

The watches that followed

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

Tornado Watch 69Feb 21, 3:25 AM CST

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 7.8 hours before the alert went out and 191 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: 116 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 604 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 193 m²/s²
0-3 km storm-relative helicity: 295 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.7

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
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, 6:47 AM CST	Mesoscale Discussion	SPC	Acadia, Ascension, Assumption, Calcasieu, Cameron, Iberia and 15 more	58 min
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 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.