MESOSCALE PRECIPITATION DISCUSSION 0724...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
834 AM EDT FRI AUG 25 2017

CORRECTED FOR TYPO IN FIRST DISCUSSION PARAGRAPH

AREAS AFFECTED...SOUTHWEST FL

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

VALID 251229Z - 251729Z

SUMMARY...FLOW ON THE SOUTHWEST SIDE OF A STRENGTHENING LOW COULD
LEAD TO HOURLY RAIN TOTALS UP TO 2.5" WITH LOCAL AMOUNTS TO 5".

DISCUSSION...A TROPICAL DISTURBANCE HAS SHOWN SOME STRENGTHENED
WINDS AT 850 HPA AROUND ITS CIRCULATION SINCE THIS TIME YESTERDAY,
WITH CONVERGENT SOUTHWEST FLOW OF UP TO 25 KTS FOCUSED INTO THE
SOUTHWEST COAST, AT LEAST TRIPLE THE VALUE OF THE MEAN 850-400 HPA
WIND.  CONVECTION APPEARS SURFACE BASED WITH NO CIN PRESENT, AND
MLCAPES OF 1000+ J/KG NEAR THE COAST AND OFFSHORE.  EFFECTIVE BULK
SHEAR OF 25 KTS IS JUST OFFSHORE, WHICH COMBINED WITH THE
UNIDIRECTIONAL FLOW WITH HEIGHT IS LEADING TO THE DEVELOPMENT OF A
COUPLE ORGANIZED SHORT BANDS AIMED INTO THE REGION.  PRECIPITABLE
WATER VALUES ARE ~2.3" PER GPS DATA.

THE MESOSCALE GUIDANCE HAS A GOOD SIGNAL FOR LOCAL AMOUNTS OF 4-5"
THROUGH 18Z, WHICH APPEARS POSSIBLE PER RECENT RADAR REFLECTIVITY.
 CLOUDY SKIES ACROSS THE REGION ARE EXPECTED TO KEEP INSTABILITY
GRADIENTS COASTAL, WHICH COULD KEEP THE HEAVY RAINFALL WITHIN THE
BANDS RELATIVELY CLOSE TO THE COASTLINE.  HOURLY RAIN TOTALS UP TO
2.5" ARE POSSIBLE IN BANDS.  THERE ARE A COUPLE AREAS NEAR THE
SOUTHWEST FL COAST WHICH HAVE RECEIVED ABOVE AVERAGE RAINFALL
DURING THE PAST WEEK, NEAR NAPLES AND FORT MYERS.  IN THESE AREAS,
AS WELL AS URBAN ENVIRONMENTS, FLASH FLOODING IS POSSIBLE.

ROTH

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

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

LAT...LON   27838237 27458184 25998105 25088107 25578134
            25808157 25828178 26118193 26338205 26468227
            26938241 27468272