Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 2389

December 22, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Dec 22, 2011, 9:32 AM CST for 4 states. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Dec 22, 2011, 9:32 AM CST (15:32 UTC)
Expired: Dec 22, 2011, 10:30 AM CST
In force: 58 min
Issued by: the Storm Prediction Center

All 45 counties

Autauga County, AL, Baldwin County, AL, Bibb County, AL, Blount County, AL, Butler County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Cullman County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Etowah County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL, Washington County, AL, Wilcox County, AL, Winston County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Harrison County, MS, Jackson County, MS

The radar

The Mobile radar (KMOB), 84 km from the middle of the area, began a volume at 15:31 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.

Tornado Watch 899Dec 22, 10:00 AM CST

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 3.5 hours before the alert went out and 215 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: 578 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 476 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 244 m²/s²
0-3 km storm-relative helicity: 297 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
Dec 22, 10:00 AM CST	Tornado Watch	SPC	Autauga, Baldwin, Barbour, Bibb, Blount, Bullock and 50 more	7 hr
Dec 22, 11:22 AM CST	Mesoscale Discussion	SPC	Choctaw, Clarke, Dallas, Marengo, Mobile, Monroe and 2 more	53 min
Dec 22, 2:51 PM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Bibb, Blount, Butler, Calhoun and 36 more	54 min
Dec 22, 4:11 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Calcasieu and 32 more	34 min
Dec 22, 4:36 AM CST	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Calcasieu and 32 more	7 hr
Dec 22, 7:50 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 19 more	55 min

Nearby

Mesoscale Discussions in Alabama, 2011 Mesoscale Discussions in Mississippi, 2011 Mesoscale Discussions in Florida, 2011 Every mesoscale discussion in 2011

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.