Alert archive / Alabama / Mesoscale Discussions in 2013

Mesoscale Discussion 2109

December 22, 201329 counties in Alabama; 12 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Dec 22, 2013, 1:34 AM CST for 29 counties in Alabama; 12 counties in Georgia. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Dec 22, 2013, 1:34 AM CST (07:34 UTC)
Expired: Dec 22, 2013, 2:30 AM CST
In force: 56 min
Issued by: the Storm Prediction Center

All 41 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Elmore County, AL, Etowah County, AL, Hale County, AL, Jackson County, AL, Jefferson County, AL, Lowndes County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Perry County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Dade County, GA, Floyd County, GA, Gordon County, GA, Haralson County, GA, Paulding County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA

The radar

The Birmingham radar (KBMX), 42 km from the middle of the area, began a volume at 07:35 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 nearest sounding before it

Birmingham, AL (KBMX), launched 00:00Z, 7.6 hours before the alert went out and 42 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: 714 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 711 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 331 m²/s²
0-3 km storm-relative helicity: 388 m²/s²
Significant tornado parameter: 1.8
Supercell composite: 6.3

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 21, 7:40 PM CST	Mesoscale Discussion	SPC	Colbert, Fayette, Franklin, Lamar, Lauderdale, Lawrence and 3 more	95 min
Dec 21, 8:16 PM CST	Tornado Watch	SPC	Blount, Colbert, Cullman, DeKalb, Fayette, Franklin and 16 more	6 hr
Dec 21, 10:33 PM CST	Mesoscale Discussion	SPC	Colbert, Fayette, Franklin, Lamar, Lauderdale, Lawrence and 3 more	87 min
Dec 21, 10:38 PM CST	Severe Thunderstorm Watch	SPC	Catoosa, Chattooga, Dade, Murray, Walker, Whitfield	6 hr
Dec 22, 4:12 AM CST	Mesoscale Discussion	SPC	Catoosa, Chattooga, Gordon, Murray, Walker, Whitfield	63 min

Nearby

Mesoscale Discussions in Alabama, 2013 Mesoscale Discussions in Georgia, 2013 Every mesoscale discussion in 2013

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.