Alert archive / Georgia / Mesoscale Discussions in 2013

Mesoscale Discussion 1721

August 15, 2013Hamilton County, Madison County, Nassau County, Florida; 11 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Aug 15, 2013, 3:09 PM EDT for Hamilton County, Madison County, Nassau County, Florida; 11 counties in Georgia. It was in force for 81 min.

The area

The outline as issued.

The facts

Issued: Aug 15, 2013, 3:09 PM EDT (19:09 UTC)
Expired: Aug 15, 2013, 4:30 PM EDT
In force: 81 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Hamilton County, FL, Madison County, FL, Nassau County, FL, Atkinson County, GA, Berrien County, GA, Brantley County, GA, Charlton County, GA, Clinch County, GA, Cook County, GA, Echols County, GA, Lanier County, GA, Lowndes County, GA, Pierce County, GA, Ware County, GA

The radar

The Moody AFB radar (KVAX), 50 km from the middle of the area, began a volume at 19:09 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, 7.2 hours before the alert went out and 83 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: 1389 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 830 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 8 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.

513 
ACUS11 KWNS 151909
SWOMCD
SPC MCD 151909 COR
GAZ000-FLZ000-152030-

MESOSCALE DISCUSSION 1721
NWS STORM PREDICTION CENTER NORMAN OK
0209 PM CDT THU AUG 15 2013

AREAS AFFECTED...SRN GA AND NRN FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 151909Z - 152030Z

CORRECTED TO CHANGE EARLY THIS EVENING TO THIS AFTERNOON IN SECOND
PARAGRAPH

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A FEW STORMS MAY BECOME CAPABLE OF PRODUCING ISOLATED
STRONG TO DAMAGING WIND GUSTS THIS AFTERNOON. OVERALL THREAT APPEARS
TOO MARGINAL TO WARRANT A WW.

DISCUSSION...A CONVECTIVELY REINFORCED QUASI-STATIONARY FRONT
EXTENDS FROM SRN GA SWWD INTO SERN AL INTO THE WRN FL PANHANDLE.
INSOLATION IN THE WARM SECTOR HAS DESTABILIZED THE VERY MOIST
BOUNDARY LAYER...BUT MLCAPE HAS BEEN LIMITED TO AOB 1500 J/KG DUE TO
WARM TEMPERATURES ALOFT AND POOR MID LEVEL LAPSE RATES. THE MOIST
THERMODYNAMIC ENVIRONMENT WITH HIGH PW AND WEAK CAP HAS PROMOTED THE
DEVELOPMENT OF NUMEROUS STORMS ALONG THE STATIONARY FRONT...IN THE
WARM SECTOR AND ALONG SW-NE CONVERGENCE BOUNDARIES EXTENDING INLAND
FROM THE GULF. VWP DATA INDICATE WEAK VERTICAL SHEAR WITH 15-20 KT
DEEP LAYER WSWLY WINDS IN WARM SECTOR. WHILE OVERALL ENVIRONMENT FOR
SEVERE STORMS IS MARGINAL...A FEW STORMS MIGHT BECOME CAPABLE OF
PRODUCING LOCALLY STRONG TO DAMAGING WING GUSTS SUPPORTED BY WATER
LOADING PROCESSES AND ESPECIALLY WHERE UPDRAFT INTENSITIES ARE
AUGMENTED BRIEFLY BY BOUNDARY/STORM MERGERS.

..DIAL/CARBIN.. 08/15/2013

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

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

LAT...LON   30628162 30378198 30168370 31058351 31548324 31368171
            30628162

Nearby

Mesoscale Discussions in Georgia, 2013 Mesoscale Discussions in Florida, 2013 Every mesoscale discussion in 2013

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.