Alert archive / Alabama / Mesoscale Discussions in 2012

Mesoscale Discussion 2219

December 25, 201215 counties in Alabama

The Storm Prediction Center issued this mesoscale discussion at Dec 25, 2012, 4:34 PM CST for 15 counties in Alabama. It was in force for 26 min.

The area

The outline as issued.

The facts

Issued
Dec 25, 2012, 4:34 PM CST (22:34 UTC)
Expired
Dec 25, 2012, 5:00 PM CST
In force
26 min
Issued by
the Storm Prediction Center
Chance of a watch
95%

Counties Bibb County, AL, Calhoun County, AL, Chambers County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Fayette County, AL, Jefferson County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tuscaloosa County, AL, Walker County, AL

The radar

The Birmingham radar (KBMX), 39 km from the middle of the area, began a volume at 22:36 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.

The nearest sounding before it

Birmingham, AL (KBMX), launched 12:00Z, 10.6 hours before the alert went out and 38 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-pSkew-T log-p diagram, Birmingham, AL at 12:00Z on 2012-12-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Birmingham, AL at 12:00Z on 2012-12-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 65 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1008 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
65 m²/s²
0-3 km storm-relative helicity
114 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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.

IssuedProductOfficeCountiesLasted
Dec 25, 12:58 PM CSTTornado Watch PDSSPCAutauga, Baldwin, Barbour, Bullock, Chambers, Choctaw and 19 more9 hr
Dec 25, 2:32 PM CSTMesoscale DiscussionSPCButler, Coffee, Conecuh, Covington, Crenshaw, Dale and 5 more28 min
Dec 25, 2:41 PM CSTTornado WatchSPCButler, Coffee, Conecuh, Covington, Crenshaw, Dale and 4 more7 hr
Dec 25, 3:44 PM CSTMesoscale DiscussionSPCAutauga, Baldwin, Butler, Choctaw, Clarke, Crenshaw and 13 more91 min
Dec 25, 4:38 PM CSTSevere Thunderstorm WatchSPCBibb, Blount, Calhoun, Chilton, Clay, Cleburne and 11 more5 hr
Dec 25, 5:17 PM CSTMesoscale DiscussionSPCBaldwin, Barbour, Bullock, Butler, Clarke, Coffee and 17 more88 min

Nearby

Mesoscale Discussions in Alabama, 2012Every 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.