Alert archive / Florida / Mesoscale Discussions in 2012
Mesoscale Discussion 2189
The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2012, 8:49 AM CST for 4 counties in Alabama; 15 counties in Florida; 14 counties in Georgia. It was in force for 56 min.
The area
The outline as issued.
The facts
- Issued
- Dec 20, 2012, 8:49 AM CST (14:49 UTC)
- Expired
- Dec 20, 2012, 9:45 AM CST
- In force
- 56 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 33 counties
Dale County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Taylor County, FL, Wakulla County, FL, Walton County, FL, Washington County, FL, Baker County, GA, Brooks County, GA, Calhoun County, GA, Clay County, GA, Colquitt County, GA, Cook County, GA, Decatur County, GA, Early County, GA, Grady County, GA, Lowndes County, GA, Miller County, GA, Mitchell County, GA, Seminole County, GA, Thomas County, GA
The radar
The Tallahassee radar (KTLH), 64 km from the middle of the area, began a volume at 14:52 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
Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 2.8 hours before the alert went out and 66 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2063 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 200 m²/s²
- 0-3 km storm-relative helicity
- 202 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
361 ACUS11 KWNS 201449 SWOMCD SPC MCD 201449 FLZ000-GAZ000-ALZ000-201545- MESOSCALE DISCUSSION 2189 NWS STORM PREDICTION CENTER NORMAN OK 0849 AM CST THU DEC 20 2012 AREAS AFFECTED...SERN AL...FL PANHANDLE...SWRN GA CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY VALID 201449Z - 201545Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...TORNADO THREAT IS INCREASING ACROSS THE FL PANHANDLE AS MARITIME TROPICAL AIRMASS BEGINS TO SPREAD INLAND. NWD EXTENT OF THIS RETURNING LOW LEVEL MOISTURE WILL BE THE GREATEST LIMITING FACTOR IN SEVERE POTENTIAL. DISCUSSION...BOUNDARY LAYER AIRMASS IS SLOWLY RECOVERING ACROSS THE FL PANHANDLE...ESPECIALLY ALONG THE COAST WHERE SFC DEW POINTS ARE NOW RISING THROUGH THE MID 60S. AS THIS AIRMASS SPREADS INLAND INCREASING BUOYANCY SHOULD ENHANCE THE PROSPECT FOR ROBUST UPDRAFTS WITHIN A STRONGLY SHEARED ENVIRONMENT...QUITE FAVORABLE FOR ROTATING UPDRAFTS AND ISOLATED SUPERCELLS. UPSTREAM...ZONE OF MULTI-BANDED PRE-FRONTAL CONVECTION WITH EMBEDDED SUPERCELLS IS PROGRESSING ACROSS AL/WRN FL PANHANDLE INTO THIS RECOVERING AIRMASS. FOR THIS REASON A NEW TORNADO WATCH WILL BE ISSUED TO ACCOUNT FOR ISOLATED TORNADO THREAT. ..DARROW/CORFIDI.. 12/20/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...JAX...TAE...BMX...MOB... LAT...LON 31888519 31068314 29608346 29648538 30788647 31888519
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 20, 4:08 AM CST | Mesoscale Discussion | SPC | Choctaw, Colbert, Fayette, Franklin, Greene, Lamar and 5 more | 67 min |
| Dec 20, 4:23 AM CST | Tornado Watch | SPC | Autauga, Baldwin, Barbour, Bibb, Bullock, Butler and 34 more | 9 hr |
| Dec 20, 7:09 AM CST | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chilton, Choctaw and 22 more | 96 min |
| Dec 20, 9:19 AM CST | Tornado Watch | SPC | Coffee, Dale, Geneva, Henry, Houston | 9 hr |
| Dec 20, 9:56 AM CST | Mesoscale Discussion | SPC | Autauga, Baldwin, Bibb, Butler, Chambers, Chilton and 22 more | 64 min |
| Dec 20, 1:31 PM CST | Mesoscale Discussion | SPC | Barbour, Coffee, Dale, Geneva, Henry, Houston and 1 more | 59 min |
| Dec 20, 5:22 PM CST | Mesoscale Discussion | SPC | Alachua, Baker, Bradford, Clay, Columbia, Dixie and 7 more | 53 min |
| Dec 20, 11:24 AM CST | Mesoscale Discussion | SPC | Baldwin, Bibb, Bleckley, Butts, Chattahoochee, Coweta and 36 more | 66 min |
Nearby
Mesoscale Discussions in Florida, 2012Mesoscale Discussions in Georgia, 2012Mesoscale 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.