MESOSCALE PRECIPITATION DISCUSSION 0021
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
459 AM EST THU JAN 28 2016
 
AREAS AFFECTED...A PORTION OF SOUTH FL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 281000Z - 281500Z
 
SUMMARY...A DEEP MOISTURE FEED...COMBINED WITH INCREASING
INSTABILITY...COULD RESULT IN FLASH FLOODING ACROSS A PORTION OF
SOUTH FL THIS MORNING. 

DISCUSSION...CONVECTION IS BEGINNING TO DEVELOP JUST OFF THE
SOUTHWEST FL COAST EARLY THIS MORNING...IN AN AXIS OF MUCAPE
VALUES TOPPING 2000 J/KG (PER THE LATEST SPC MESOANALYSIS). THE
DEVELOPING CONVECTION IS BEING FEED BY A CHANNEL OF 2.00+ INCH
PRECIPITABLE WATER AIR (AS SEEN ON THE MOST RECENT BLENDED TPW
IMAGERY). HOURLY RAINFALL RATES ON THE LATEST MRMS PRODUCT SHOWED
VALUES BETWEEN 1.50 AND 2.50 INCHES...WHILE THE KBYX RADAR SHOWED
HOURLY RAINFALL RATES CLOSER TO 1.50 INCHES. 

THE DEEP MOISTURE AND INSTABILITY IS EXPECTED TO BECOME FOCUSED ON
A ZONE OF LOW LEVEL CONVERGENCE STRETCHING FROM KAPF TO KSUA.
PRECIPITABLE WATER VALUES SHOULD TOP 2.00 INCHES (WHICH IS BETWEEN
TWO AND THREE STANDARD DEVIATIONS ABOVE THE MEAN) ALONG THIS AXIS
(PER THE LATEST HRRR/RAP). MOST OF THE AVAILABLE HIGH RESOLUTION
GUIDANCE SUGGESTS THAT THE BEST INSTABILITY REMAINS JUST
OFFSHORE...THOUGH THE LATEST HRRR DOES SHOW THAT MUCAPE VALUES
NEAR 1000 J/KG COULD BECOME ENTRAINED ALONG THE BOUNDARY AFTER
13Z. 

THE CONVECTION IS EXPECTED TO COME ONSHORE ACROSS SOUTHWEST FL
BETWEEN 10Z AND 11Z. THE BEST THRUST OF MOISTURE AND INSTABILITY
IS EXPECTED IN THE 12Z TO 15Z TIME FRAME...AND THIS IS EXPECTED
TIME OF HIGHEST RAINFALL RATES...WHICH COULD LOCALLY EXCEED 2
INCHES. 

THERE IS SOME SPREAD ON THE PLACEMENT OF THE HIGHEST QPF AXIS
ASSOCIATED WITH THE LOW TOPPED CONVECTION. THE LATEST HRRR AND 00Z
WRF ARW PLACE THE HIGHEST QPF AXIS FROM NEAR FMY TO THE WESTERN
SHORE OF THE LAKE. BASED ON THE LATEST RADAR TRENDS... THIS AXIS
PLACEMENT COULD END UP BEING TOO FAR NORTH.

THERE IS FAIRLY GOOD AGREEMENT THAT LOCAL 2 TO 4 INCH RAINFALL
AMOUNTS ARE POSSIBLE ALONG THE CONVECTIVE AXIS THROUGH 15Z...
ESPECIALLY WHERE CONVECTION TRAINS. IT SHOULD BE NOTED THAT 00Z
WRF ARW AND THE 06Z NAM CONEST SHOWED MAXIMUM QPF AMOUNTS NEAR 6
INCHES...BUT THESE AMOUNTS COULD BE OVERDONE. THESE AMOUNTS ARE IN
ADDITION TO HEAVY RAINFALL EXPERIENCED OVER PORTIONS OF THE AREA
WEDNESDAY AND WEDNESDAY NIGHT.

THE POTENTIAL FOR FLASH FLOODING COULD EXPECTED BEYOND THE 15Z
TIME FRAME.

HAYES

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

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

LAT...LON   26968080 26948065 26788026 26498024 26268037 
            26178042 26058046 25798070 25588100 25478113 
            25448124 25428133 25418151 25458176 25588202 
            25648207 25778221 25858228 26368214 26458206 
            26628184 26678170 26778150 26868126 26908112 
            26928103