Flash Flood Guidance
Issued by NWS

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117
AWUS01 KWNH 041720
FFGMPD
FLZ000-042230-

MESOSCALE PRECIPITATION DISCUSSION 0178
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
119 PM EDT WED MAY 04 2016

AREAS AFFECTED...CENTRAL AND SOUTH FL...

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

VALID 041720Z - 042230Z

SUMMARY...THE NEXT THRUST OF DEEP MOISTURE AHEAD OF A SHORT WAVE
APPROACHING SOUTHWEST FL WILL CONTINUE TO FEED CONVECTION ACROSS
CENTRAL AND SOUTH FL. THE COMBINATION OF HOURLY RAINFALL RATES
NEAR 2 INCHES...AND THE SHORT TERM TRAINING...COULD RESULT IN A
LOCALIZED FLASH FLOOD THREAT THROUGH THE LATE AFTERNOON.

DISCUSSION...REGIONAL RADARS CONTINUE TO SHOW CONVECTION DROPPING
SLOWLY SOUTH ACROSS CENTRAL FL...AS THE NEXT BATCH OF CONVECTION
WITH HEAVY RAINFALL COMES ASHORE AHEAD OF A SHORT WAVE APPROACHING
SOUTHWEST FL. REGIONAL RADARS AND THE MRMS PRECIPITABLE RATE
PRODUCTS INDICATED HOURLY RATES BETWEEN 2.00 AND 2.50 INCHES
BETWEEN PUNTA GORDA AND FORT MYERS. GROUND TRUTH REPORTS EARLIER
SUGGEST THESE VALUES ARE FAIRLY CLOSE.

THE NEXT SURGE OF 1.75 TO 2.00 INCH PRECIPITABLE WATER AIR (AS
SHOWN ON THE LATEST BLENDED TPW IMAGES) IS COMING ASHORE ACROSS
SOUTH FL AHEAD OF THE SHORT WAVE. MLCAPE ACROSS SOUTH FL RANGE
BETWEEN 2000 AND 4000 J/KG...WHICH IS SUPPORTING CONVECTIVE
ACTIVITY ON THE SEA BREEZE BOUNDARY ACROSS SOUTHEAST FL. THE
STRONG INSTABILITY SHOULD SUPPORT THE CONVECTIVE ACTIVITY AS IT
CROSSES CENTRAL AND SOUTH FL THROUGH THE LATE AFTERNOON HOURS.

THE LATEST HRRR APPEARS TO BE A BIT TOO FAR NORTH WITH THE
NORTHERN EDGE OF THE CONVECTION AT 17Z...AS DOES THE LATEST RAP.
ADJUSTING FOR THE POSITIONAL DIFFERENCES...MOST OF THE CAM
GUIDANCE IS SUGGESTING THAT THE HOURLY RAINFALL RATES NEAR 2.00
INCHES WILL CONTINUE WITH THE CONVECTION AS IT CROSSES CENTRAL AND
SOUTH FL. THE UNIDIRECTIONAL MID LEVEL FLOW COULD RESULT IN SHORT
TERM TRAINING... ESPECIALLY OVER PORTIONS OF SOUTHWEST FL. LOCAL 2
TO 4 INCH RAINFALL AMOUNTS ARE POSSIBLE...AS WAS SEEN EARLIER IN
THE SARASOTA AREA. THE COMBINATION OF HIGH RAINFALL RATES AND
POTENTIAL TRAINING COULD RESULT IN A LOCALIZED FLASH FLOOD
THREAT...ESPECIALLY IN URBAN AREAS.

HAYES

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

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

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

LAT...LON   27458124 27318037 26728006 25238011 25108071
            25198128 25748180 26938249 27348208



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