Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 2192

December 20, 201242 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2012, 12:24 PM EST for 42 counties in Georgia. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Dec 20, 2012, 12:24 PM EST (17:24 UTC)
Expired: Dec 20, 2012, 1:30 PM EST
In force: 66 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 42 counties

Baldwin County, GA, Bibb County, GA, Bleckley County, GA, Butts County, GA, Chattahoochee County, GA, Coweta County, GA, Crawford County, GA, Crisp County, GA, Dooly County, GA, Fayette County, GA, Hancock County, GA, Harris County, GA, Henry County, GA, Houston County, GA, Jasper County, GA, Jones County, GA, Lamar County, GA, Macon County, GA, Marion County, GA, Meriwether County, GA, Monroe County, GA, Morgan County, GA, Muscogee County, GA, Newton County, GA, Peach County, GA, Pike County, GA, Pulaski County, GA, Putnam County, GA, Rockdale County, GA, Schley County, GA, Spalding County, GA, Stewart County, GA, Sumter County, GA, Talbot County, GA, Taylor County, GA, Troup County, GA, Twiggs County, GA, Upson County, GA, Washington County, GA, Webster County, GA, Wilcox County, GA, Wilkinson County, GA

The radar

The Atlanta radar (KFFC), 69 km from the middle of the area, began a volume at 17:25 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

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 5.4 hours before the alert went out and 65 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2398 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 257 m²/s²
0-3 km storm-relative helicity: 408 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.

483 
ACUS11 KWNS 201725
SWOMCD
SPC MCD 201724
GAZ000-ALZ000-201830-

MESOSCALE DISCUSSION 2192
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CST THU DEC 20 2012

AREAS AFFECTED...CENTRAL GA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 201724Z - 201830Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...TORNADO WATCH WILL LIKELY BE REQUIRED ACROSS PARTS OF
CNTRL GA IN RESPONSE TO APPROACHING CORRIDOR OF EMBEDDED SUPERCELLS
AND PRE-FRONTAL SQUALL LINE.

DISCUSSION...PRE-FRONTAL SQUALL LINE OVER AL CONTINUES ITS
PROGRESSION EWD AT ROUGHLY 35-40KT.  PORTIONS OF THIS LINE HAVE
GRADUALLY INCREASED IN INTENSITY/ORGANIZATION OVER THE LAST
HOUR...ESPECIALLY ACROSS ELMORE/MONTGOMERY/BUTLER COUNTIES IN AL.
THIS ACTIVITY SHOULD SPREAD INTO DOWNSTREAM PORTIONS OF GA BY 19Z
WHERE BOUNDARY LAYER AIRMASS IS SLOWLY MOISTENING/WARMING.  THERE IS
SOME CONCERN THAT 30-40 MI WIDE BAND OF WEAKER CONVECTION MAY IMPEDE
HEATING AS IT PRECEDES PRIMARY SQUALL LINE OF INTEREST.  WHILE
DAMAGING WINDS MAY BE THE PRIMARY SEVERE THREAT WITH CONVECTIVE
LINE...ENVIRONMENTAL SHEAR IS VERY STRONG AND ISOLATED TORNADOES CAN
NOT BE RULED OUT.

..DARROW/CORFIDI.. 12/20/2012

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

ATTN...WFO...FFC...BMX...

LAT...LON   33258520 33738389 33528290 32818263 31858346 32028506
            33258520

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 20, 9:49 AM EST	Mesoscale Discussion	SPC	Baker, Brooks, Calhoun, Clay, Colquitt, Cook and 8 more	56 min
Dec 20, 10:19 AM EST	Tornado Watch	SPC	Baker, Calhoun, Clay, Decatur, Dougherty, Early and 8 more	9 hr
Dec 20, 2:31 PM EST	Mesoscale Discussion	SPC	Baker, Calhoun, Clay, Colquitt, Decatur, Dougherty and 13 more	59 min
Dec 20, 6:22 PM EST	Mesoscale Discussion	SPC	Camden, Charlton, Clinch, Echols, Ware	53 min

Nearby

Mesoscale Discussions in Georgia, 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.