Alert archive / Georgia / Mesoscale Discussions in 2015

Mesoscale Discussion 21

January 4, 201510 counties in Florida; 30 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jan 4, 2015, 7:48 AM CST for 10 counties in Florida; 30 counties in Georgia. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Jan 4, 2015, 7:48 AM CST (13:48 UTC)
Expired: Jan 4, 2015, 9:15 AM CST
In force: 87 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 40 counties

Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Wakulla County, FL, Baker County, GA, Ben Hill County, GA, Berrien County, GA, Brooks County, GA, Calhoun County, GA, Colquitt County, GA, Cook County, GA, Crisp County, GA, Decatur County, GA, Dooly County, GA, Dougherty County, GA, Early County, GA, Grady County, GA, Irwin County, GA, Lee County, GA, Macon County, GA, Miller County, GA, Mitchell County, GA, Randolph County, GA, Schley County, GA, Seminole County, GA, Sumter County, GA, Telfair County, GA, Terrell County, GA, Thomas County, GA, Tift County, GA, Turner County, GA, Webster County, GA, Wilcox County, GA, Worth County, GA

The radar

The Tallahassee radar (KTLH), 27 km from the middle of the area, began a volume at 13:49 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 3Jan 4, 10:40 AM CST

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 1.8 hours before the alert went out and 29 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: 300 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 484 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 210 m²/s²
0-3 km storm-relative helicity: 208 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

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

142 
ACUS11 KWNS 041349
SWOMCD
SPC MCD 041348 
GAZ000-FLZ000-ALZ000-041515-

MESOSCALE DISCUSSION 0021
NWS STORM PREDICTION CENTER NORMAN OK
0748 AM CST SUN JAN 04 2015

AREAS AFFECTED...FAR SE AL...SW GA...FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 041348Z - 041515Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A MARGINAL WIND DAMAGE THREAT AND A BRIEF TORNADO WILL BE
POSSIBLE ACROSS SW GA...FAR SE AL AND THE FL PANHANDLE OVER THE NEXT
FEW HOURS. THE MAGNITUDE OF ANY SEVERE THREAT IS NOT EXPECTED TO BE
ENOUGH TO WARRANT WW ISSUANCE.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A COLD FRONT ACROSS SE AL
WITH A CORRIDOR OF LOW-LEVEL MOISTURE EXTENDING FROM THE ERN FL
PANHANDLE NNEWD ACROSS MUCH OF THE SRN HALF OF GA. SFC DEWPOINTS
ALONG THIS CORRIDOR ARE IN THE 65 TO 70 F RANGE WITH A NEARLY
CONTINUOUS LINE OF STORMS ONGOING ALONG THE WRN EDGE OF THE MOIST
CORRIDOR. THIS SQUALL-LINE SHOULD CONTINUE TO MOVE ACROSS SW GA AND
INTO THE ERN FL PANHANDLE OVER THE NEXT FEW HOURS WHERE SFC WINDS
ARE SOUTH TO SOUTH-SOUTHWESTERLY. THIS ALONG WITH SLIGHTLY VEERING
WINDS WITH HEIGHT MAY RESULT IN ENOUGH LOW-LEVEL SHEAR FOR A BRIEF
TORNADO WITH ROTATING CELL ELEMENTS EMBEDDED IN THE LINE. IN
ADDITION...THE WSR-88D VWP AT TALLAHASSEE SHOWS 0-6 KM SHEAR NEAR 50
KT WITH 30 TO 35 KT OF FLOW JUST OFF THE SFC. THIS MAY BE ENOUGH FOR
A MARGINAL WIND DAMAGE THREAT WITH LINE SEGMENTS THAT CAN ACCELERATE
A BIT FASTER THAN THE LINE ITSELF AND DEVELOP BOWING STRUCTURE.

..BROYLES/EDWARDS.. 01/04/2015

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

ATTN...WFO...JAX...FFC...TAE...

LAT...LON   29808395 29468460 29488515 29748563 30128569 30808543
            32558421 31918285 29808395

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 4, 1:19 AM CST	Mesoscale Discussion	SPC	Escambia, Okaloosa, Santa Rosa, Walton	86 min
Jan 4, 9:28 AM CST	Mesoscale Discussion	SPC	Baker, Columbia, Duval, Hamilton, Jefferson, Lafayette and 7 more	92 min
Jan 4, 10:37 AM CST	Tornado Watch	SPC	Baker, Columbia, Dixie, Gilchrist, Hamilton, Jefferson and 7 more	5 hr
Jan 4, 12:39 PM CST	Mesoscale Discussion	SPC	Columbia, Hamilton, Lafayette, Madison, Suwannee, Taylor	96 min
Jan 4, 2:57 PM CST	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Clay, Duval, Nassau and 3 more	63 min
Jan 3, 7:54 PM CST	Mesoscale Discussion	SPC	Chattooga, Dade, Floyd, Haralson, Polk, Walker	66 min

Nearby

Mesoscale Discussions in Georgia, 2015 Mesoscale Discussions in Florida, 2015 Every mesoscale discussion in 2015

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.