Alert archive / Mississippi / Mesoscale Discussions in 2009

Mesoscale Discussion 2282

December 24, 200922 parishes in Louisiana; 23 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Dec 24, 2009, 9:34 AM CST for 22 parishes in Louisiana; 23 counties in Mississippi. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Dec 24, 2009, 9:34 AM CST (15:34 UTC)
Expired: Dec 24, 2009, 10:30 AM CST
In force: 56 min
Issued by: the Storm Prediction Center

All 45 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines 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 Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Simpson County, MS, Stone County, MS, Walthall County, MS, Wilkinson County, MS

The watches that followed

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

Tornado Watch 808Dec 24, 10:40 AM CST

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.6 hours before the alert went out and 56 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: 255 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 477 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 395 m²/s²
0-3 km storm-relative helicity: 501 m²/s²
Significant tornado parameter: 0.1
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 23, 7:50 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Red River and 2 more	85 min
Dec 23, 8:48 PM CST	Tornado Watch	SPC	Beauregard, Bienville, Bossier, Caddo, Calcasieu, Cameron and 7 more	9 hr
Dec 23, 11:06 PM CST	Mesoscale Discussion	SPC	Beauregard, Bienville, Bossier, Caddo, Claiborne, De Soto and 5 more	114 min
Dec 24, 3:30 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 42 more	2 hr
Dec 24, 4:50 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 47 more	7 hr
Dec 24, 7:30 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Caldwell and 39 more	90 min
Dec 24, 10:13 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Caldwell, Catahoula, Concordia, East Baton Rouge and 29 more	62 min
Dec 24, 10:37 AM CST	Tornado Watch	SPC	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Charles, Saint Tammany and 2 more	7 hr
Dec 24, 1:14 PM CST	Mesoscale Discussion	SPC	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Tammany, Washington	61 min
Dec 24, 3:33 PM CST	Mesoscale Discussion	SPC	Clarke, Forrest, George, Greene, Harrison, Jackson and 11 more	57 min

Nearby

Mesoscale Discussions in Mississippi, 2009 Mesoscale Discussions in Louisiana, 2009 Every mesoscale discussion in 2009

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.