Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 765

May 9, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 9, 2012, 11:59 AM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 9, 2012, 11:59 AM CDT (16:59 UTC)
Expired: May 9, 2012, 2:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 70 counties

Houston County, AL, Bay County, FL, Calhoun County, FL, Gadsden County, FL, Gulf County, FL, Hamilton County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Wakulla County, FL, Washington County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Baker County, GA, Ben Hill County, GA, Berrien County, GA, Brantley County, GA, Brooks County, GA, Bryan County, GA, Bulloch County, GA, Calhoun County, GA, Camden County, GA, Candler County, GA, Charlton County, GA, Chatham County, GA, Clinch County, GA, Coffee County, GA, Colquitt County, GA, Cook County, GA, Crisp County, GA, Decatur County, GA, Dodge County, GA, Dougherty County, GA, Early County, GA, Echols County, GA, Effingham County, GA, Evans County, GA, Glynn County, GA, Grady County, GA, Irwin County, GA, Jeff Davis County, GA, Lanier County, GA, Lee County, GA, Liberty County, GA, Long County, GA, Lowndes County, GA, McIntosh County, GA, Miller County, GA, Mitchell County, GA, Montgomery County, GA, Pierce County, GA, Screven County, GA, Seminole County, GA, Tattnall County, GA, Telfair County, GA, Thomas County, GA, Tift County, GA, Toombs County, GA, Treutlen County, GA, Turner County, GA, Ware County, GA, Wayne County, GA, Wheeler County, GA, Wilcox County, GA, Worth County, GA, Hampton County, SC, Jasper County, SC

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 269May 9, 1:00 PM CDT

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 5.0 hours before the alert went out and 154 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: 420 J/kg
Mixed-layer CIN: -52 J/kg
Mixed-layer LCL: 904 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 35 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.

841 
ACUS11 KWNS 091659
SWOMCD
SPC MCD 091659 
SCZ000-GAZ000-FLZ000-ALZ000-091900-

MESOSCALE DISCUSSION 0765
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT WED MAY 09 2012

AREAS AFFECTED...FAR SRN SC/SRN GA/PARTS OF NRN FL AND THE FL
PANHANDLE/FAR SERN AL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 091659Z - 091900Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...DESTABILIZING AIRMASS AHEAD OF THE SLOWLY ADVANCING COLD
FRONT SHOULD PERMIT INCREASING CONVECTIVE DEVELOPMENT THIS
AFTERNOON.  DEGREE OF SEVERE POTENTIAL MAY EVENTUALLY REQUIRE WW
ISSUANCE.

DISCUSSION...LATEST VISIBLE SATELLITE IMAGERY SHOWS PARTLY CLOUDY
CONDITIONS -- AND THUS ONGOING HEATING/DESTABILIZATION -- FROM SERN
SC WSWWD INTO THE FL PANHANDLE AHEAD OF THE ADVANCING COLD FRONT. 
OBJECTIVE ANALYSES SHOW MIXED-LAYER CAPE VALUES NOW INTO THE 1000 TO
1500 J/KG RANGE ACROSS THIS AREA...SUPPORTING A CONVECTIVE INCREASE
OBSERVED IN BOTH RADAR AND VISIBLE SATELLITE IMAGERY.

WHILE THE KINEMATIC ENVIRONMENT ACROSS THIS AREA REMAINS MODEST --
FLOW REMAINS GENERALLY UNIDIRECTIONAL FROM THE WSW AND LESS THAN 30
KT THROUGH THE LOWER HALF OF THE TROPOSPHERE...MODEST INCREASES IN
MID-LEVEL FLOW ARE POSSIBLE AS THE UPPER TROUGH SHIFTS SEWD WITH
TIME THUS INCREASING THE HEIGHT GRADIENT.

GIVEN THE COMBINATION OF FURTHER/MODEST DESTABILIZATION AND SOME
POSSIBLE INCREASE IN THE MID-LEVEL FLOW FIELD...A FEW STRONGER
STORMS SHOULD BECOME CAPABLE OF PRODUCING AT LEAST MARGINAL HAIL AND
LOCALLY GUSTY/DAMAGING WINDS.  THIS EVOLUTION COULD REQUIRE SEVERE
THUNDERSTORM WATCH ISSUANCE -- POSSIBLY IN THE NEXT 1-2 HOURS.

..GOSS/MEAD.. 05/09/2012

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

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

LAT...LON   32728061 31018138 30728181 29658506 30378621 31508515
            32468248 33058116 32728061

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 5:01 PM CDT	Mesoscale Discussion	SPC	Alachua, Baker, Bradford, Clay, Columbia, Dixie and 17 more	89 min
May 9, 10:32 AM CDT	Mesoscale Discussion	SPC	Burke, Richmond	88 min
May 9, 1:00 PM CDT	Severe Thunderstorm Watch	SPC	Bryan, Bulloch, Candler, Chatham, Effingham, Evans and 4 more	5 hr
May 9, 3:54 PM CDT	Mesoscale Discussion	SPC	Bryan, Chatham, Liberty, Long, McIntosh, Wayne	96 min
May 9, 6:04 PM CDT	Mesoscale Discussion	SPC	Bryan, Chatham, Effingham, Liberty, Long, McIntosh	26 min

Nearby

Mesoscale Discussions in Georgia, 2012 Mesoscale Discussions in Florida, 2012 Mesoscale Discussions in South Carolina, 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.