MESOSCALE PRECIPITATION DISCUSSION 0599
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1020 AM EDT SUN JUL 30 2017

AREAS AFFECTED...CENTRAL AND NORTHERN FL

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

VALID 301420Z - 301900Z

SUMMARY...VERY HEAVY RAINFALL FROM REPEATING BANDS OF SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO FOSTER RUNOFF AND/OR FLASH FLOODING
CONCERNS.

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS A TRAINING BAND OF
VERY HEAVY SHOWERS AND THUNDERSTORMS SETTING UP FROM COLUMBIA
COUNTY EAST-SOUTHEAST TO CLAY AND ST. JOHNS COUNTIES OF NORTHEAST
FL WHICH IS SOUTH OF THE JACKSONVILLE METROPOLITAN AREA. THE
CONVECTION HAS BEEN INTENSIFYING OVER THE LAST HOUR AND THE
CONVECTIVE CLOUD TOPS CONTINUE COOL. MEANWHILE...ADDITIONAL AREAS
OF FOCUSED CONVECTION ARE NOTED ON THE GULF SIDE OF THE PENINSULA
FROM LEVY COUNTY DOWN TO CITRUS AND HERNANDO COUNTIES.

THE ACTIVITY IS FOCUSING WITHIN A HIGHLY CONFLUENT LOW LEVEL FLOW
REGIME WITH A VERY MOIST AND MODERATELY UNSTABLE AIRMASS POOLED
ALONG A SURFACE FRONTAL ZONE WHERE MULTIPLE WAVES OF LOW PRESSURE
HAVE BEEN HELPING TO PROVIDE LOCALLY ENHANCED SURFACE CONVERGENCE.
PWATS ARE NEAR 2.5 INCHES WITH A DEEP TROPICAL AIRMASS IN
PLACE...WHICH WILL BE CONDUCIVE TO HIGHLY EFFICIENT RAINFALL
PROCESSES. MUCAPE VALUES OF 1500 TO 2000+ J/KG ARE IN PLACE...AND
THE CONVECTION THIS MORNING HAS BEEN TENDING TO FOCUS WITHIN THE
PERSISTENT GRADIENT OF THE INSTABILITY AXIS.

RAINFALL RATES OF UP TO 3 INCHES/HR ARE EXPECTED...WITH ADDITIONAL
RAINFALL AMOUNTS THROUGH MID-AFTERNOON OF LOCALLY OVER 5 INCHES
GIVEN THE PERSISTENCE OF THE SURFACE CONVERGENCE/FORCING NEAR THE
FRONT AND POOLING OF SUCH DEEP MOIST/UNSTABLE AIR ALONG IT.
ENHANCED RUNOFF AND/OR FLASH FLOODING WILL BE POSSIBLE.

ORRISON

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

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

LAT...LON   30498272 30398198 30278145 29988123 29448098
            29158085 28398090 28078138 27888208 27988283
            28698310 29128307 29548337 29878335 30308321