MESO: Mesoscale Discussion 0196

ACUS11 KWNS 171252
SWOMCD
SPC MCD 171252
FLZ000-171515-

MESOSCALE DISCUSSION 0196
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT MON MAR 17 2014

AREAS AFFECTED...THE CENTRAL FLORIDA PENINSULA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 171252Z - 171515Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE RISK FOR SEVERE THUNDERSTORMS...INCLUDING
TORNADOES...IS EXPECTED TO GRADUALLY INCREASE THIS MORNING. THIS MAY
NECESSITATE THE ISSUANCE OF A TORNADO WATCH DURING THE NEXT COUPLE
OF HOURS OR SO.

DISCUSSION...A CORRIDOR OF DEEP CONVECTION HAS PERSISTED THROUGH
MUCH OF THE NIGHT OVER THE EAST GULF/LOOP CURRENT INVOF A
NE/SW-ORIENTED LOW-LEVEL CONFLUENCE AXIS WITHIN A WARM CONVEYOR
IMPLIED BY OVERNIGHT MOISTURE-CHANNEL IMAGERY. SFC ANALYSIS REVEALS
A QUASI-STATIONARY FRONT ROUGHLY ALIGNING WITH THIS ACTIVITY THAT
EXTENDS FROM BROAD LOW PRESSURE IN THE MIDDLE GULF TO NRN FL.
THETA-E DEFICITS OWING TO PERSISTENT CONVECTIVE OVERTURNING ROUGHLY
N OF A LINE FROM CITRUS TO FLAGLER/VOLUSIA COUNTIES ARE REINFORCING
THIS BOUNDARY. S OF THE BOUNDARY...POSITIVE MOISTURE ADVECTION IS
SUPPORTING AN INFLUX OF MIDDLE-UPPER 60S DEWPOINTS AMIDST SFC-BASED
EFFECTIVE INFLOW LAYERS PER 12Z TBW...MFL...AND KEY RAOBS. SLIGHTLY
HIGHER DEWPOINTS LIE ALONG THE W FL COAST NEAR AND S OF TAMPA WHERE
SOME ONSHORE FLOW COMPONENT OFF THE E GULF IS BREEDING AN INLAND
MANIFESTATION OF LATENT HEAT FLUXES ATOP THE WARMER GULF WATERS.

TBW VWP DATA INDICATE 50-65 KT OF SWLY/WSWLY FLOW IN THE 4-7-KM-AGL
LAYER -- I.E. POSSESSING SOME /ALBEIT LIMITED/ COMPONENT ORTHOGONAL
TO THE AMALGAMATION OF E-GULF MESO-BETA-SCALE CONVECTIVE ELEMENTS.
THIS WILL CONTINUE TO FOSTER A GRADUAL NET EWD MOTION OF THE
STRONGER CONVECTION TOWARD THE W FL COAST THROUGH THE MORNING.
MEANWHILE...MODEST DIURNAL SFC-LAYER HEATING BENEATH THE
MID/HIGH-LEVEL CLOUD CANOPY...SHED DOWNSTREAM OF ONGOING
CONVECTION...WILL CONTRIBUTE TO CONTINUED DESTABILIZATION TO THE S
OF THE AFOREMENTIONED SFC BOUNDARY. ALREADY...THE 12Z TBW RAOB
INDICATES AROUND 1000 J/KG OF MLCAPE WITH NEGLIGIBLE MLCINH.

THE JUXTAPOSITION OF THE PREVIOUSLY MENTIONED STRONG MID-LEVEL FLOW
WITH A 35 KT LLJ SAMPLED BY THE TBW AND MLB VWP/S AND THE 12Z TBW
RAOB WILL MAINTAIN THE POTENTIAL FOR ORGANIZED CONVECTION.
CONVECTIVE MODE WILL LIKELY CONSIST OF QUASI-LINEAR SEGMENTS WITH
EMBEDDED LEWP/BOWING STRUCTURES COMING OFF THE GULF WATERS AND
SPREADING ACROSS THE CNTRL FL PENINSULA THROUGH THE DAY --
ESPECIALLY AFTER 1430Z. AS THE LLJ STRENGTHENS WITH THE APPROACH OF
A SHORTWAVE IMPULSE ENTERING THE NW GULF...HIGH-MOMENTUM AIR JUST
ABOVE THE SFC WILL FAVOR THE POTENTIAL FOR DAMAGING WIND GUSTS.
FURTHERMORE...THE 12Z TBW RAOB ALREADY INDICATES AROUND 30 KT OF
0-1-KM SHEAR...AND THE MAGNITUDE OF SHEAR IN THIS LAYER SHOULD
INCREASE AS THE LLJ STRENGTHENS. THIS WILL POTENTIALLY FOSTER
LINE-EMBEDDED MESOVORTICES/POSSIBLE SUPERCELLS WITH TORNADOES.

AT THIS TIME...THERE IS SOME UNCERTAINTY REGARDING THE TIMING OF
INITIATION OF MORE ROBUST UPDRAFTS SUPPORTED BY INLAND DIURNAL
DESTABILIZATION. VISIBLE SATELLITE IMAGERY SUGGESTS THAT CLOUDS
COULD IMPEDE THIS PROCESS TO SOME EXTENT IN THE SHORT-TERM...THOUGH
AT LEAST SOME GRADUAL INCREASE IN THE SVR POTENTIAL WILL OCCUR
THROUGH THE MORNING.

..COHEN/EDWARDS.. 03/17/2014

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

ATTN...WFO...MFL...MLB...TBW...

LAT...LON 27888280 28428259 29048106 28218058 27708048 27018092
26568193 27328260 27888280

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