Flash Flood Guidance
Issued by NWS

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000
AWUS01 KWNH 020052
FFGMPD
FLZ000-020510-

MESOSCALE PRECIPITATION DISCUSSION 0405...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
852 PM EDT SAT AUG 01 2015

CORRECTED FOR SPELLING

AREAS AFFECTED...CENTRAL AND NORTHERN FL PENINSULA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 012310Z - 020510Z

SUMMARY...ADDITIONAL BANDS OF VERY HEAVY RAIN WILL FOCUS
ADDITIONAL FLOODING CONCERNS THROUGH THE EVENING HOURS WHICH MAY
BE SIGNIFICANT.

DISCUSSION...THE POTENTIAL WILL EXIST THROUGH THE LATE EVENING
HOURS FOR VERY HEAVY RAINFALL TOTALS IN ADDITION TO EARLIER
HEAVIER RAINS ACROSS PORTIONS OF THE GULF COAST OF FL. THE MAIN
FOCUS OVER THE NEXT SEVERAL HOURS WILL BE AREAS ALONG AND JUST
INLAND FROM THE GULF OF MEXICO...FROM NEAR APPALACHEE BAY TO CROSS
CITY WHERE ALREADY A CONCENTRATED BAND OF VERY HEAVY SHOWERS HAS
SET UP. A SEPARATE CONVECTIVE BAND WITH VERY HEAVY SHOWERS IS SET
UP FARTHER SOUTH OVER THE FAR EASTERN GULF OF MEXICO WHICH IS
APPROACHING THE GREATER TAMPA BAY AREA.

MUCH OF THE GULF COAST OF FL HAS SEEN VERY HEAVY RAINFALL OVER THE
LAST WEEK...AND ANY ADDITIONAL RAINS WILL EXACERBATE ONGOING
FLOODING CONCERNS. THE HEAVY CONVECTIVE RAINS ARE ASSOCIATED WITH
A WELL-DEFINED AND EXTREMELY MOIST UNIDIRECTIONAL LOW TO MID LEVEL
SOUTHWESTERLY FETCH COMING IN OFF THE GULF OF MEXICO TO THE SOUTH
OF AN AREA OF LOW PRESSURE OVER THE FL PANHANDLE AND A SW/NE
ORIENTED SHEAR AXIS WHICH EXTENDS UP THROUGH 700 MB. THE
PERSISTENT AND UNIDIRECTIONAL FETCH IS ALLOWING THE HEAVY RAIN TO
TRAIN OVER THE SAME AREA...WITH RAINFALL RATES EXCEEDING 2.5
INCHES/HR AT TIMES.

OVER THE NEXT SEVERAL HOURS...THE HIRES GUIDANCE INCLUDING THE 12Z
NMMB AND 12Z NSSL-WRF SUGGESTS A STRONGLY ORGANIZED AND
CONCENTRATED CORE OF CONVECTION IMPACTING AREAS IN AND AROUND
DIXIE COUNTY WHICH INCLUDES CROSS CITY. THE LATEST SATELLITE AND
RADAR TRENDS ALREADY DEPICT THIS BEGINNING TO OCCUR GIVEN
INCREASED LOW LEVEL FORCING/CONVERGENCE...AND SO THESE MODELS ARE
BEING GIVEN SIGNIFICANT WEIGHTING RIGHT NOW. EXPECT ADDITIONAL
RAINFALL TOTALS OF 3 TO 6 INCHES WITH LOCALLY HEAVIER AMOUNTS
POTENTIALLY EXCEEDING 8 INCHES ACROSS THESE AREAS THROUGH
MIDNIGHT. SIGNIFICANT FLOODING IS EXPECTED AS A RESULT.

MEANWHILE...FARTHER SOUTH INTO THE CENTRAL FL PENINSULA...EXPECT
ADDITIONAL SHORT-TERM HEAVY RAINFALL POTENTIAL OF UP TO A COUPLE
OF INCHES...ESPECIALLY AROUND TAMPA BAY...BUT THEN IMPROVEMENT
THROUGH MID TO LATE EVENING AS DIMINISHING INSTABILITY WILL CAUSE
CONVECTION TO WEAKEN AND DIMINISH. REGARDLESS...ANY ADDITIONAL
RAINS WILL CAUSE RUNOFF PROBLEMS HERE AS WELL.

ORRISON

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

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

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

LAT...LON   30438366 30198287 29778252 29118232 28438213
            27368228 27368266 27528287 27948304 28338319
            28928326 29528352 29788392 29808466 30308447



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