Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 011538
FFGMPD
FLZ000-GAZ000-012136-

MESOSCALE PRECIPITATION DISCUSSION 0403
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1137 AM EDT SAT AUG 01 2015

AREAS AFFECTED...NORTHERN FLORIDA PENINSULA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 011536Z - 012136Z

SUMMARY...RELATIVE LULL IN FLOODING THREAT WITH INCREASED CELL
MOTION AND WEAK INSTABILITIES IN THE SURFACE TROF.  SOME INCREASED
SHORT TERM FLASH FLOODING/URBAN FLOODING THREATS IN THE
PANHANDLE/CENTRAL FL GULF COAST.

DISCUSSION...REFOCUS OF LOW LEVEL SURFACE LOW TOWARD THE WEST
SOUTH OF THE AAF...HAS LEAD TO A DECREASE OF NEAR COASTAL
CONVERGENCE NEAR THE MCS WEST OF CEDAR KEY...AND WEAKENING OF THE
COMPLEX OVERALL. THIS HAS ALLOWED FOR INCREASED OUTFLOW AND
EASTWARD PROPAGATION OF CONVECTIVE ROLLS SEEN IN RADAR/VISIBLE
LOOP.  THESE CELLS REMAIN HIGHLY EFFICIENT (SEE EARLIER SPENES
ABOUT TPWS IN EXCESS OF 2.25-2.4") IN RAINFALL PRODUCTION BUT DUE
TO INCREASED FORWARD PROGRESS TOTAL DEPTH OF THE CONVECTION HAS BE
SEVERELY DIMINISHED DUE TO 50KTS RELATIVE SHEAR AND SKINNY
PROFILES...FOR MORE ROBUST UPDRAFTS TO WITHSTAND SAID SHEAR.
STILL WITH UPPER LEVEL 20-25KT FLOW AND 25-30KT LOW LEVEL FLOW
NEARLY PARALLEL...CELL MOTIONS ALLOW FOR THE TILTED CORES TO RAIN
UPON THE TRACKS...FOR EFFECTIVE TRAINING AND INCREASED TOTALS TO
SET THE STAGE FOR THE POTENTIAL FOR INCREASED FLOODING LATER
TONIGHT THOUGH THE REST OF THE WEEKEND. THIS SHOULD ALSO ALLOW A
RECHARGE OF INSTABILITIES IN THE NEAR TERM (PRIOR 21Z) BEFORE NEXT
ROUND LATER THIS EVENING.

STILL NEARLY 60-80 DEGREES OF LOW LEVEL FLOW REMAINS GENERALLY
CONVERGENT TO THE NORTHEAST GULF COAST FOR ADVECTION OF
INSTABILITIES WITH CAPES IN THE 1500-2000 J/KG IN THE NEXT FEW
HOURS...PARTICULARLY FROM CEDAR KEY SOUTH TOWARD TAMPA/SARASOTA.
FRICTIONAL CONVERGENCE AT THE COASTLINE WITH THIS STRONG ONSHORE
FLOW SHOULD ALLOW FOR CONTINUED CONVECTIVE DEVELOPMENT AND
POTENTIAL FOR REPEAT DEVELOPMENT INCREASING RAINFALL TOTALS FROM
GENERAL 1-2" TO 2-4" WITHIN THE NEXT 6HRS.

IN THE PANHANDLE...NORTH OF THE SURFACE LOW CLEARER SKIES HAVE
ALLOWED FOR SBCPAES TO INCREASE INTO THE 3000 J/KG RANGE.
SLACKENED UPPER LEVEL FLOW DIRECTLY UNDER THE UPPER RIDGE ALLOWS
FOR SOME DIVERGENCE BUT REDUCED SHEAR TO ALLOW FOR BETTER VERTICAL
GROWTH AND SLOWER CELL MOTIONS TOWARDS THE SOUTHWEST. THESE
CONVECTIVE CELLS COULD PRODUCE 2-3"/HR RATES WITH ISOLATED TOTALS
POTENTIALLY SLIGHTLY HIGHER GIVEN THE REDUCED DURATION/PROLONGED
ORGANIZATION OF THESE CELLS IN THE NEAR TERM.

GALLINA

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAX...MLB...TAE...TBW...

ATTN...RFC...SERFC...

LAT...LON   30578378 30498304 30348202 30558155 30348108
            29568096 28848154 28048204 26908228 27228290
            28448300 29078313 29338361 29358446 29468492
            29688527 30178532



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