Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 134

February 19, 2012Nassau County, Florida; 20 counties in Georgia; Beaufort County, Jasper County, South Carolina

The Storm Prediction Center issued this mesoscale discussion at Feb 19, 2012, 12:20 PM EST for Nassau County, Florida; 20 counties in Georgia; Beaufort County, Jasper County, South Carolina. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: Feb 19, 2012, 12:20 PM EST (17:20 UTC)
Expired: Feb 19, 2012, 1:45 PM EST
In force: 85 min
Issued by: the Storm Prediction Center

All 23 counties

Nassau County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Brantley County, GA, Bryan County, GA, Bulloch County, GA, Camden County, GA, Charlton County, GA, Chatham County, GA, Clinch County, GA, Effingham County, GA, Evans County, GA, Glynn County, GA, Liberty County, GA, Long County, GA, McIntosh County, GA, Pierce County, GA, Tattnall County, GA, Ware County, GA, Wayne County, GA, Beaufort County, SC, Jasper County, SC

The radar

The Charleston,SC radar (KCLX), 128 km from the middle of the area, began a volume at 17:22 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

Jacksonville, FL (KJAX), launched 12:00Z, 5.3 hours before the alert went out and 128 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: 178 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 471 m above ground
0-6 km bulk shear: 78 kt
0-1 km storm-relative helicity: 396 m²/s²
0-3 km storm-relative helicity: 506 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

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

488 
ACUS11 KWNS 191720
SWOMCD
SPC MCD 191720 
SCZ000-GAZ000-FLZ000-191845-

MESOSCALE DISCUSSION 0134
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CST SUN FEB 19 2012

AREAS AFFECTED...SERN GA...FAR SRN SC

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 191720Z - 191845Z

A FEW TSTMS MAY FORM SHORTLY WITHIN SW-NE ORIENTED CLOUD STREETS
ACROSS PARTS OF SERN GA. DESPITE THE PRESENCE OF SUBSTANTIAL DRY AIR
IN THE MID-LEVELS...A WARMING BOUNDARY LAYER AND STRONG DEEP-LAYER
SHEAR SHOULD SUPPORT A RISK FOR LOCALLY DAMAGING WINDS WITH ANY
SUSTAINED CONVECTION. THE PROBABILITY OF A WW ISSUANCE IS 20
PERCENT.

17Z SURFACE ANALYSIS PLACED A 1005 CYCLONE IN E-CNTRL GA WITH A COLD
FRONT EXTENDING SWWD ACROSS S-CNTRL GA INTO THE ERN FL PANHANDLE. A
FEW SHOWERS HAVE GRADUALLY DEEPENED AHEAD OF THE FRONT WITHIN SW-NE
ORIENTED CLOUD STREETS ACROSS SERN GA. WATER VAPOR IMAGERY AND
UPSTREAM 12Z RAOBS INDICATE THE PREVALENCE OF MID-LEVEL DRYNESS
LIKELY ENTRAINING WITH SURFACE-BASED PARCELS...WHILE MODEST
MID-LEVEL LAPSE RATES ARE LIMITING INSTABILITY.
NEVERTHELESS...SURFACE TEMPERATURES HAVE NOW REACHED THE MIDDLE 70S
TO LOWER 80S AND GIVEN THE GLANCING INFLUENCE OF ASCENT ASSOCIATED
WITH THE SRN APPALACHIANS SHORT WAVE IMPULSE...TSTM DEVELOPMENT MAY
COMMENCE SHORTLY. STRONG LINE-PARALLEL DEEP-LAYER FLOW /EFFECTIVE
SHEAR AROUND 70 KT/ WILL BE FAVORABLE FOR A POTENTIALLY ORGANIZED
CLUSTER PRIMARILY CAPABLE OF LOCALLY DAMAGING WINDS.

..GRAMS.. 02/19/2012

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

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

LAT...LON   31728266 32278215 32568149 32678099 32728078 32658024
            32438023 31708094 30558145 30528161 30438206 30588266
            30978298 31308289 31728266

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 18, 8:05 PM EST	Mesoscale Discussion	SPC	Bay, Calhoun, Columbia, Dixie, Franklin, Gadsden and 16 more	55 min
Feb 18, 8:24 PM EST	Tornado Watch	SPC	Baker, Bay, Calhoun, Columbia, Franklin, Gadsden and 14 more	6 hr
Feb 18, 11:36 PM EST	Mesoscale Discussion	SPC	Baker, Bay, Calhoun, Columbia, Franklin, Gadsden and 11 more	84 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.