Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 2218

December 25, 201219 counties in Alabama; 25 parishes in Louisiana; 33 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Dec 25, 2012, 3:44 PM CST for 19 counties in Alabama; 25 parishes in Louisiana; 33 counties in Mississippi. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Dec 25, 2012, 3:44 PM CST (21:44 UTC)
Expired: Dec 25, 2012, 5:15 PM CST
In force: 91 min
Issued by: the Storm Prediction Center

All 77 counties

Autauga County, AL, Baldwin County, AL, Butler County, AL, Choctaw County, AL, Clarke County, AL, Crenshaw County, AL, Dallas County, AL, Greene County, AL, Hale County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pike County, AL, Sumter County, AL, Washington County, AL, Wilcox County, AL, Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafayette 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 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, Amite County, MS, Clarke County, MS, Copiah 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, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 65 km from the middle of the area, began a volume at 21:45 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watches that followed

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

Severe Thunderstorm Watch 697Dec 25, 4:40 PM CST

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 9.7 hours before the alert went out and 102 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: 790 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 576 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 181 m²/s²
0-3 km storm-relative helicity: 237 m²/s²
Significant tornado parameter: 1.1
Supercell composite: 10.0

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 25, 12:58 PM CST	Tornado Watch PDS	SPC	Autauga, Baldwin, Barbour, Bullock, Chambers, Choctaw and 19 more	9 hr
Dec 25, 2:32 PM CST	Mesoscale Discussion	SPC	Butler, Coffee, Conecuh, Covington, Crenshaw, Dale and 5 more	28 min
Dec 25, 2:41 PM CST	Tornado Watch	SPC	Butler, Coffee, Conecuh, Covington, Crenshaw, Dale and 4 more	7 hr
Dec 25, 4:34 PM CST	Mesoscale Discussion	SPC	Bibb, Calhoun, Chambers, Clay, Cleburne, Coosa and 9 more	26 min
Dec 25, 4:38 PM CST	Severe Thunderstorm Watch	SPC	Bibb, Blount, Calhoun, Chilton, Clay, Cleburne and 11 more	5 hr
Dec 25, 5:17 PM CST	Mesoscale Discussion	SPC	Baldwin, Barbour, Bullock, Butler, Clarke, Coffee and 17 more	88 min
Dec 25, 1:01 AM CST	Mesoscale Discussion	SPC	Allen, Beauregard, Sabine, Vernon	59 min
Dec 25, 1:37 AM CST	Severe Thunderstorm Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, De Soto and 9 more	7 hr
Dec 25, 5:56 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, De Soto and 10 more	94 min
Dec 25, 7:00 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 24 more	60 min
Dec 25, 7:28 AM CST	Tornado Watch	SPC	Acadia, Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia and 19 more	6 hr
Dec 25, 8:46 AM CST	Mesoscale Discussion	SPC	Allen, Avoyelles, Beauregard, Bienville, Calcasieu, Caldwell and 21 more	59 min
Dec 25, 9:02 AM CST	Severe Thunderstorm Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Catahoula, Claiborne and 20 more	7 hr
Dec 25, 9:17 AM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more	8 hr
Dec 25, 12:19 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 35 more	71 min
Dec 25, 12:23 PM CST	Mesoscale Discussion	SPC	Bienville, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 13 more	67 min
Dec 25, 3:22 PM CST	Mesoscale Discussion	SPC	Caldwell, East Carroll, Morehouse, Richland, West Carroll	53 min

Nearby

Mesoscale Discussions in Mississippi, 2012 Mesoscale Discussions in Louisiana, 2012 Mesoscale Discussions in Alabama, 2012 Every mesoscale discussion in 2012

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; radar from the NEXRAD Level II archive.