MESO: Mesoscale Discussion 0799

ACUS11 KWNS 131221
SWOMCD
SPC MCD 131220
FLZ000-131315-

MESOSCALE DISCUSSION 0799
NWS STORM PREDICTION CENTER NORMAN OK
0720 AM CDT SUN MAY 13 2012

AREAS AFFECTED...FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 131220Z - 131315Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE POTENTIAL FOR ISOLATED/BRIEF TORNADOES MAY INCREASE
ACROSS WRN COASTAL SECTIONS OF THE FL PANHANDLE THIS MORNING.
TORNADO POTENTIAL IS LIKELY TO REMAIN TOO LIMITED IN TIME/SPACE FOR
A WATCH.

DISCUSSION...RADAR/SATL AND LTG TRENDS ALL INDICATE AN INCREASE IN
TSTMS ALONG A WEAK CONFLUENCE AXIS AND SFC LOW PRESSURE AREA MOVING
INTO THE EXTREME WRN PORTION OF THE FL PNHDL. A WARM FRONT IS ALSO
SITUATED ONSHORE FROM EAST OF MOBILE BAY EWD ALONG THE IMMEDIATE
GULF COAST TO APALACHICOLA. A WARM AND VERY MOIST AIRMASS IS FUELING
THIS RECENT DEVELOPMENT THAT IS ALSO BEING SUPPORTED BY THE APPROACH
OF A MID LEVEL SHORT WAVE TROUGH/40KT JET STREAK PER LATEST
OBJECTIVE DATA.

TLH VWP AND MODEL SOUNDINGS SHOW A VEERING VERTICAL WIND PROFILE
INDICATIVE OF WARM ADVECTION OCCURRING ACROSS THE WARM FRONT AND
RESULTING IN A CORRIDOR OF ENHANCED SRH AROUND 200 M2/S2 ACROSS THE
IMMEDIATE GULF COAST. DISCRETE STORM UPDRAFTS AMIDST THIS SHEARED
FLOW REGIME HAVE EXHIBITED WEAK BUT PERSISTENT ROTATION OVER THE
LAST HOUR OR SO WITH ONE CELL MOVING ACROSS FORT WALTON BEACH AND A
NUMBER OF OTHER CELLS BETWEEN 20 AND 60 MILES OFFSHORE.

STORM SCALE GUIDANCE INCLUDING THE HRRR APPEARS TO BE RELATIVELY
ACCURATE IN DEPICTING THE CURRENT INCREASE IN TSTM COVERAGE MOST
LIKELY DUE TO THE INCREASE IN LARGE SCALE ASCENT ACCOMPANYING THE
APPROACHING SHORT WAVE TROUGH. THIS GUIDANCE ALONG WITH OTHER STORM
SCALE ENSEMBLE GUIDANCE SUPPORT AN INCREASING POTENTIAL FOR ROTATING
STORMS TO CROSS THE WRN FL PANHANDLE AREA THROUGH THE MORNING.
STRENGTH OF STORM UPDRAFTS ARE CURRENTLY LIMITED BY GENERALLY WEAK
LAPSE RATES CONTRIBUTING TO ONLY LIMITED SFC-BASED INSTABILITY.
AND...DESPITE MODEST DIRECTIONAL SHEAR IN THE UPDRAFT
LAYER...OVERALL STRENGTH OF THE FLOW IS LIKELY TO LIMIT MESOCYCLONE
STRENGTH. NONETHELESS...A WEAK/BRIEF TORNADO OR TWO CANNOT BE
COMPLETELY RULED OUT...ESPECIALLY AS CONVECTION INCREASES THROUGH
THE MORNING AND SOME POTENTIAL EXISTS FOR FURTHER GRADUAL DIURNAL
BOUNDARY LAYER DESTABILIZATION. THE OVERALL POTENTIAL APPEARS
LIMITED IN SPACE AND TIME AND A WATCH IS UNLIKELY.

..CARBIN/THOMPSON.. 05/13/2012

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

ATTN...WFO...TAE...MOB...

LAT...LON 30338723 30678718 30808665 30738617 30508571 30068553
30058646 30338723

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