MESOSCALE PRECIPITATION DISCUSSION 0734...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
106 AM EDT SAT AUG 26 2017

CORRECTED FOR SUMMARY SECTION

AREAS AFFECTED...CNTRL TO SWRN FL PENINSULA

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

VALID 260458Z - 261045Z

SUMMARY...LOCALLY HEAVY RAINFALL IS EXPECTED TO CONTINUE THROUGH
THE MORNING ALONG THE CENTRAL TO SOUTHWESTERN FLORIDA PENINSULA.
RAINFALL RATE POTENTIAL OF 3 IN/HR ALONG WITH TRAINING COULD LEAD
TO LOCALIZED FLASH FLOODING.

DISCUSSION...A 04Z MESOSCALE SURFACE ANALYSIS REVEALED AT LEAST 3
AREAS OF LOW PRESSURE IN WESTERN FLORIDA WITH THE MAIN ONE
SITUATED OVER TAMPA BAY ALONG WITH SEVERAL LOW LEVEL CONVERGENCE
AXES. EXPERIMENTAL GOES 16 INFRARED IMAGERY HAS SHOWN THE COLDEST
CLOUD TOPS PERSISTENTLY ALONG THE COAST OR JUST OFFSHORE BETWEEN
TAMPA BAY AND CHARLOTTE HARBOR OVER THE PAST 1-2 HOURS. ZOOMING IN
WITH KTBW RADAR DATA REVEALS THE HEAVIEST RAINFALL RATES IN THESE
AREAS...2-3 IN/HR...HAS BEEN TIED TO TRANSIENT MESO-VORTICES
MEANDERING OFFSHORE TO ALONG THE CENTRAL AND SOUTHWESTERN COAST OF
FLORIDA WHERE BETTER NEAR-SURFACED BASED INSTABILITY IS PRESENT.

THE SURFACE LOW OVER TAMPA BAY HAS BEEN CONSISTENTLY FORECAST BY
RECENT RUNS OF THE RAP TO REMAIN NEARLY STATIONARY THROUGH 12Z
WHILE A SUBTLE INCREASE IN 850 MB WIND SPEEDS DEVELOPS BY 10Z
SOMEWHERE BETWEEN TAMPA BAY AND CHARLOTTE HARBOR. THESE LOCATIONS
DOWN TO COLLIER COUNTY ARE WHERE 2-6 INCHES OF RAIN HAS FALLEN
OVER THE PAST 24 HOURS. THE STRONGER 850 MB FLOW COMBINED WITH
WEAK SOUTHWESTERLY STEERING FLOW SHOULD ALLOW FOR ONE OR TWO
LOCATIONS NEAR THE COAST TO SEE TRAINING HEAVY RAINFALL WITH
RAINFALL RATES POSSIBLY EXCEEDING 3 IN/HR GIVEN PRECIPITABLE WATER
VALUES OVER 2.25 INCHES AND LOCALLY HIGHER INSTABILITY JUST
OFFSHORE AND ALONG THE COAST. GIVEN ANTECEDENT CONDITIONS AND
EXPECTED ADDITIONAL RAINFALL TOTALS UP TO 4-6
INCHES...LOCALLY...FLASH FLOODING WILL BE POSSIBLE.

OTTO

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

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

LAT...LON   28058210 27808158 27098135 26388126 25868135
            25608163 25778209 26068235 27218293 27618278
            27958250