MESO: Mesoscale Discussion 1730

ACUS11 KWNS 161803
SWOMCD
SPC MCD 161803
FLZ000-GAZ000-162030-

MESOSCALE DISCUSSION 1730
NWS STORM PREDICTION CENTER NORMAN OK
0103 PM CDT FRI AUG 16 2013

AREAS AFFECTED...PORTIONS OF SRN GA AND NRN FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 161803Z - 162030Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...AN ISOLATED DAMAGING WIND GUST WILL BE POSSIBLE THIS
AFTERNOON.

DISCUSSION...A PLUME OF RICH DEEP MOISTURE WITHIN A WARM CONVEYOR
BELT E OF A MID-LEVEL TROUGH OVER PARTS OF THE SERN STATES IS
CHARACTERIZED BY GPS PW VALUES OF 2.0-2.2 INCHES ACROSS THE
AREA...WITH SFC OBS INDICATING DEWPOINTS IN THE LOWER AND MIDDLE
70S. THE 12Z RAOBS AT CHS...JAX...AND TLH INDICATE DEEP LAYERS OF
NEARLY MOIST-NEUTRAL PROFILES IN SECTIONS OF THE LOWER/MIDDLE
TROPOSPHERE WITH GENERALLY POOR MID-LEVEL LAPSE RATES.
HOWEVER...LOW-LEVEL LAPSE RATES ARE DIURNALLY STEEPENING IN RESPONSE
TO MODEST INSOLATION IN AREAS OF AT LEAST PARTIAL SUNSHINE --
GENERALLY ON THE WARM SIDE OF A WAVY...QUASI-STATIONARY...
CONVECTIVE-OUTFLOW-AUGMENTED SYNOPTIC BOUNDARY. EARLY THIS
AFTERNOON...THIS BOUNDARY WAS ANALYZED FROM SSE OF SAVANNAH GA TO
WEAK LOW PRESSURE NW VIDALIA GA TO ANOTHER WEAK LOW NNE OF MARIANA
FL THAT EXTENDS FARTHER SW INTO THE NRN GULF OF MEXICO.

CONVECTION IS FORECAST TO INCREASE IN COVERAGE AND INTENSITY DURING
THE NEXT FEW HOURS AMIDST A MODERATELY TO STRONGLY UNSTABLE AIR MASS
AND VERY WEAK INHIBITION PER MODIFIED 12Z RAOBS. FOCI FOR ENHANCED
THUNDERSTORM COVERAGE INCLUDE THE FOLLOWING:
/1/ CONVERGENCE ALONG THE SYNOPTIC BOUNDARY...
/2/ ASCENT ACCOMPANYING DIFFERENTIAL HEATING ZONES OVER THE
PERIPHERIES OF MULTI-LAYERED CLOUD DECKS SCATTERED ACROSS THE
AREA...
/3/ LIFT INVOF REMNANT OUTFLOW BOUNDARIES ACROSS THE REGION...AND
/4/ ASCENT INVOF A SFC CONFLUENCE AXIS THAT ENTERS SWRN PARTS OF THE
MCD AREA FROM THE MIDDLE AND EASTERN GULF.

UPDRAFT INTENSITY WILL LARGELY BE MITIGATED BY WEAK MID-LEVEL LAPSE
RATES. HOWEVER...WITH A BAND OF 20-25 KT OF MID-LEVEL FLOW E OF THE
TROUGH -- STRONGEST NEAR THE AUGMENTED SYNOPTIC BOUNDARY -- A FEW
MARGINALLY ORGANIZED STORM CLUSTERS MAY OCCUR. AND...WITH THE HIGH
PW IN PLACE SUPPORTING ABUNDANT WATER LOADING...AN ISOLATED DMGG
WIND GUST CANNOT BE RULED OUT.

..COHEN/KERR.. 08/16/2013

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

ATTN...WFO...CHS...MLB...TBW...JAX...FFC...TAE...

LAT...LON 30348560 31628343 32298231 32348144 31968106 30788146
29308103 28788165 28848264 29878385 29658527 30348560

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