Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 865

May 22, 2012Hamilton County, Florida; 44 counties in Georgia; Abbeville County, Edgefield County, McCormick County, South Carolina

The Storm Prediction Center issued this mesoscale discussion at May 22, 2012, 1:46 PM EDT for Hamilton County, Florida; 44 counties in Georgia; Abbeville County, Edgefield County, McCormick County, South Carolina. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 22, 2012, 1:46 PM EDT (17:46 UTC)
Expired: May 22, 2012, 2:45 PM EDT
In force: 59 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 48 counties

Hamilton County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Brantley County, GA, Bulloch County, GA, Burke County, GA, Candler County, GA, Charlton County, GA, Clarke County, GA, Clinch County, GA, Coffee County, GA, Columbia County, GA, Echols County, GA, Elbert County, GA, Emanuel County, GA, Evans County, GA, Glascock County, GA, Greene County, GA, Hancock County, GA, Jeff Davis County, GA, Jefferson County, GA, Jenkins County, GA, Johnson County, GA, Lanier County, GA, Lincoln County, GA, Long County, GA, Madison County, GA, McDuffie County, GA, Montgomery County, GA, Oglethorpe County, GA, Pierce County, GA, Richmond County, GA, Screven County, GA, Taliaferro County, GA, Tattnall County, GA, Telfair County, GA, Toombs County, GA, Treutlen County, GA, Ware County, GA, Warren County, GA, Washington County, GA, Wayne County, GA, Wheeler County, GA, Wilkes County, GA, Abbeville County, SC, Edgefield County, SC, McCormick County, SC

The radar

The Robins AFB radar (KJGX), 90 km from the middle of the area, began a volume at 17:46 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

Jacksonville, FL (KJAX), launched 12:00Z, 5.8 hours before the alert went out and 209 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: 398 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 1333 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 6 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.

989 
ACUS11 KWNS 221747
SWOMCD
SPC MCD 221746
GAZ000-SCZ000-FLZ000-221845-

MESOSCALE DISCUSSION 0865
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CDT TUE MAY 22 2012

AREAS AFFECTED...PARTS OF ERN GA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 221746Z - 221845Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...TSTMS ARE EXPECTED TO CONTINUE DEVELOPING OVER THE ERN
HALF OF GA THIS AFTERNOON AS THE AIR MASS UNDERGOES FURTHER
DESTABILIZATION.  WW ISSUANCE IS UNCERTAIN AT THIS TIME...GIVEN THE
LACK OF STRONGER DEEP LAYER SHEAR FOR STORM ORGANIZATION...BUT
CONVECTIVE TRENDS WILL BE MONITORED THAT COULD RESULT IN WW ISSUANCE
BEING GREATER THAN 40 PERCENT.

DISCUSSION...TRENDS IN VISIBLE SATELLITE IMAGERY EARLY THIS
AFTERNOON INDICATED CU/TCU INCREASING IN AREAL COVERAGE FROM EAST
CENTRAL THROUGH NERN GA INTO UPSTATE SC.  OBJECTIVE ANALYSES SHOWED
MUCAPE CURRENTLY RANGING FROM 1000 TO 2000 J/KG...WITH ADDITIONAL
DIABATIC HEATING AIDING IN FURTHER DESTABILIZATION AND STEEPENING
LOW LEVEL LAPSE RATES.  DESPITE WEAK MIDLEVEL LAPSE RATES ATTM...THE
AFOREMENTIONED THERMODYNAMICS COMBINED WITH FORCING FOR ASCENT/
MIDLEVEL COLD ADVECTION ATTENDANT TO THE EWD MOVING MID-UPPER
LOW...NOW ADVANCING INTO WRN/CENTRAL GA PER WATER VAPOR IMAGERY...
SUGGEST UPDRAFTS SHOULD BECOME DEEPER/CONDUCIVE FOR TSTM
DEVELOPMENT.

GIVEN THE TRACK OF THE MID-UPPER LOW...THE STRONGER FLOW ALOFT
SHOULD BE FOCUSED ACROSS SRN GA/NRN FL INTO ERN SC WITH THESE AREAS
HAVING THE GREATEST POTENTIAL FOR STORM ORGANIZATION AND THE NEED
FOR A WW.  UNIDIRECTIONAL WSWLY WIND FIELDS WITH BULK SHEAR OF 20-30
KT SUGGEST MULTICELLS AND LINE SEGMENTS SHOULD BE THE PRIMARY STORM
MODES.

..PETERS/WEISS.. 05/22/2012

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

ATTN...WFO...CHS...CAE...GSP...JAX...FFC...TAE...

LAT...LON   30878322 32518286 33698329 34118351 34488253 33948187
            32758154 31718157 30918178 30588215 30408295 30878322

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 1:10 PM EDT	Mesoscale Discussion	SPC	Broward, Collier, Glades, Hendry, Martin, Miami-Dade and 4 more	2 hr
May 22, 4:43 PM EDT	Severe Thunderstorm Watch	SPC	Bay, Calhoun, Franklin, Gadsden, Gulf, Jackson and 7 more	4 hr
May 22, 3:32 PM EDT	Severe Thunderstorm Watch	SPC	Bryan, Bulloch, Candler, Chatham, Effingham, Evans and 6 more	5 hr
May 22, 6:58 PM EDT	Mesoscale Discussion	SPC	Chatham	62 min
May 22, 2:29 PM EDT	Mesoscale Discussion	SPC	Dillon, Georgetown, Horry, Marion, Marlboro, Williamsburg	91 min

Nearby

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