Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 266

March 16, 201230 counties in Alabama; 36 counties in Georgia; 10 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Mar 16, 2012, 12:40 PM CDT for 30 counties in Alabama; 36 counties in Georgia; 10 counties in Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Mar 16, 2012, 12:40 PM CDT (17:40 UTC)
Expired: Mar 16, 2012, 2:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 76 counties

Bibb County, AL, Blount County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Cullman County, AL, DeKalb County, AL, Etowah County, AL, Fayette County, AL, Franklin County, AL, Jackson County, AL, Jefferson County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marion County, AL, Marshall County, AL, Morgan County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Winston County, AL, Bartow County, GA, Carroll County, GA, Catoosa County, GA, Chattooga County, GA, Cherokee County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, Dade County, GA, Dawson County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Floyd County, GA, Forsyth County, GA, Fulton County, GA, Gilmer County, GA, Gordon County, GA, Gwinnett County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Lamar County, GA, Meriwether County, GA, Murray County, GA, Paulding County, GA, Pickens County, GA, Pike County, GA, Polk County, GA, Rockdale County, GA, Spalding County, GA, Troup County, GA, Upson County, GA, Walker County, GA, Whitfield County, GA, Bradley County, TN, Coffee County, TN, Franklin County, TN, Grundy County, TN, Hamilton County, TN, Lincoln County, TN, Marion County, TN, Moore County, TN, Polk County, TN, Sequatchie County, TN

The radar

The Birmingham radar (KBMX), 103 km from the middle of the area, began a volume at 17:44 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

Birmingham, AL (KBMX), launched 12:00Z, 5.7 hours before the alert went out and 103 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: 769 J/kg
Mixed-layer CIN: -78 J/kg
Mixed-layer LCL: 1195 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 68 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.

357 
ACUS11 KWNS 161741
SWOMCD
SPC MCD 161740
GAZ000-TNZ000-ALZ000-161945-

MESOSCALE DISCUSSION 0266
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT FRI MAR 16 2012

AREAS AFFECTED...NRN AL...NW GA...SE TN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 161740Z - 161945Z

THUNDERSTORMS WILL INCREASE IN COVERAGE THE NEXT FEW HOURS.
MARGINALLY SEVERE HAIL AND GUSTY WINDS WILL BE THE MAIN THREAT WITH
PULSE-LIKE CONVECTION THROUGH THE AFTERNOON HOURS.
ADDITIONALLY...SLOW STORM MOTION WILL ALLOW FOR LOCALLY HEAVY
DOWNPOURS.

THUNDERSTORMS WERE DEVELOPING AHEAD OF AN OUTFLOW BOUNDARY FROM
EARLY MORNING CONVECTION ACROSS MIDDLE TN. AS TEMPERATURES HAVE
WARMED INTO THE MID 70S TO LOW 80S EARLY THIS AFTERNOON...THE AIR
MASS HAS BECOME UNCAPPED WITH SBCAPE VALUES NEAR 2000 J/KG. PER
REGIONAL 12Z RAOBS AND LATEST MESOANALYSIS...STEEP MIDLEVEL LAPSE
RATES NEAR 7-7.5 DEG C/KM COMBINED WITH AFOREMENTIONED MODERATE
INSTABILITY WILL LEAD TO ROBUST UPDRAFTS. HOWEVER...IN THE ABSENCE
OF DEEP LAYER FORCING FOR ASCENT AND VERY WEAK EFFECTIVE SHEAR
/10-15 KT/...STRONG UPDRAFTS ARE EXPECTED TO BE BRIEF. THEREFORE
ORGANIZED SEVERE WEATHER IS NOT ANTICIPATED AND ONLY SPORADIC
INSTANCES OF LARGE HAIL ARE EXPECTED AND A WW IS NOT NEED.

..LEITMAN.. 03/16/2012

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...

LAT...LON   32708472 32618589 32698668 32908726 33358784 33908808
            34338810 34568794 34838763 35668582 35438500 35178450
            34478411 33438392 32968409 32708472

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 16, 2:25 PM CDT	Mesoscale Discussion	SPC	Appling, Atkinson, Bacon, Baldwin, Ben Hill, Berrien and 68 more	2 hr

Nearby

Mesoscale Discussions in Georgia, 2012 Mesoscale Discussions in Alabama, 2012 Mesoscale Discussions in Tennessee, 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.