Alert archive / Louisiana / Mesoscale Discussions in 2007

Mesoscale Discussion 2246

December 20, 20075 counties in Alabama; 36 parishes in Louisiana; 20 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2007, 11:21 AM CST for 5 counties in Alabama; 36 parishes in Louisiana; 20 counties in Mississippi. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Dec 20, 2007, 11:21 AM CST (17:21 UTC)
Expired: Dec 20, 2007, 12:45 PM CST
In force: 84 min
Issued by: the Storm Prediction Center

All 61 counties

Baldwin County, AL, Choctaw County, AL, Clarke County, AL, Mobile County, AL, Washington County, AL, Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Saint Bernard 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, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Vermilion Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Clarke County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jones County, MS, Lamar County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 5.4 hours before the alert went out and 82 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: 178 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 781 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 161 m²/s²
0-3 km storm-relative helicity: 200 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

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
Dec 20, 10:01 AM CST	Tornado Watch	SPC	Baldwin, Choctaw, Clarke, Mobile, Washington	5 hr
Dec 20, 11:50 AM CST	Tornado Watch	SPC	Butler, Conecuh, Covington, Escambia, Monroe	5 hr
Dec 20, 1:03 PM CST	Mesoscale Discussion	SPC	Baldwin, Conecuh, Escambia, Mobile, Monroe	57 min
Dec 19, 10:12 PM CST	Mesoscale Discussion	SPC	Allen, Beauregard, Calcasieu, Sabine, Vernon	93 min
Dec 20, 3:30 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Bienville, Bossier, Caddo and 14 more	90 min
Dec 20, 8:48 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu and 19 more	57 min
Dec 20, 9:15 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 30 more	7 hr
Dec 20, 1:06 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 21 more	84 min

Nearby

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