Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 2215

December 25, 201211 counties in Alabama; 12 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Dec 25, 2012, 2:32 PM CST for 11 counties in Alabama; 12 counties in Florida. It was in force for 28 min.

The area

The outline as issued.

The facts

Issued: Dec 25, 2012, 2:32 PM CST (20:32 UTC)
Expired: Dec 25, 2012, 3:00 PM CST
In force: 28 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 23 counties

Butler County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Pike County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Franklin County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Liberty County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL

The radar

The Eglin Afb radar (KEVX), 6 km from the middle of the area, began a volume at 20:32 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 696Dec 25, 2:45 PM CST

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 8.5 hours before the alert went out and 162 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: 212 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 448 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 64 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

845 
ACUS11 KWNS 252032
SWOMCD
SPC MCD 252032 
FLZ000-GAZ000-ALZ000-252100-

MESOSCALE DISCUSSION 2215
NWS STORM PREDICTION CENTER NORMAN OK
0232 PM CST TUE DEC 25 2012

AREAS AFFECTED...SOUTH CENTRAL-SERN AL AND WRN FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 

VALID 252032Z - 252100Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THE WARM SECTOR ENVIRONMENT ACROSS THE FL PANHANDLE INTO
SOUTH CENTRAL-SERN AL WILL REMAIN CONDUCIVE TO SUPPORT ORGANIZED
STORMS INTO THE EVENING WITH AN INCREASING POTENTIAL FOR AT LEAST A
TORNADO OR TWO.  THIS THREAT WILL BE ATTENDANT TO STORMS CURRENTLY
MOVING NWD FROM THE GULF OF MEXICO...AND ALSO AS ACTIVITY DEVELOPS
EWD FROM SERN LA AND SRN MS THIS EVENING.

DISCUSSION...MID AFTERNOON SURFACE ANALYSIS INDICATED A WARM FRONT
HAD MOVED NORTH OF MUCH OF THE FL PANHANDLE INTO SRN AL. THE WARM
SECTOR WAS DESTABILIZING...AND GIVEN INCREASING DEEP LAYER AND LOW
LEVEL SHEAR EXPECTED AS THE STRONG SHORTWAVE TROUGH PROGRESSES EWD
INTO THE EVENING...A TORNADO THREAT IS EXPECTED TO INCREASE.

..PETERS/EDWARDS.. 12/25/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...TAE...BMX...MOB...

LAT...LON   29958713 31018748 32058676 31798554 31518504 30408481
            29698468 29358509 30028614 29958713

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, 2:41 PM CST	Tornado Watch	SPC	Butler, Coffee, Conecuh, Covington, Crenshaw, Dale and 4 more	7 hr
Dec 25, 3:44 PM CST	Mesoscale Discussion	SPC	Autauga, Baldwin, Butler, Choctaw, Clarke, Crenshaw and 13 more	91 min
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, 5:57 PM CST	Mesoscale Discussion	SPC	Gadsden, Jefferson, Leon, Liberty, Madison, Wakulla	2 hr

Nearby

Mesoscale Discussions in Florida, 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.