MESOSCALE PRECIPITATION DISCUSSION 0635
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
832 PM EDT FRI SEP 02 2016
 
AREAS AFFECTED...WRN AND NRN FL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 030030Z - 030600Z
 
SUMMARY...A NARROW AXIS OF HEAVY RAINFALL IS EXPECTED TO BECOME
BETTER DEFINED ACROSS NRN FLORIDA OVER THE NEXT FEW HOURS.
ALSO...ADDITIONAL NARROW REGIONS OF TRAINING MAY PERSIST FARTHER
SOUTH ALONG THE WRN FL PENINSULA. GIVEN HEAVY RAINFALL OVER THE
PAST 24-36 HOURS ACROSS THESE REGIONS...FLASH FLOODING WILL BE
POSSIBLE.
 
DISCUSSION...00Z RADAR IMAGERY SHOWED A BROKEN LINE OF CONVECTION
EXTENDING WEST TO EAST OVER NRN FL FROM THE CNTRL FL PANHANDLE TO
THE NERN FL COAST. THIS AREA OF STORMS HAS FORMED WITHIN AN AXIS
OF CONFLUENT/CONVERGENT LOW LEVEL FLOW LOCATED BETWEEN T.S.
HERMINE AND SWLY FLOW IN THE ERN GULF OF MEXICO. 00Z SOUNDINGS
FROM TLH AND JAX INDICATED PRECIPITABLE WATER VALUES BETWEEN 2.1
TO 2.3 INCHES AND MLCAPE OF 1000-2000 J/KG. 

SHORT TERM RAP FORECASTS HAVE BEEN CONSISTENT WITH THE AREA OF
CONVERGENCE PERSISTING ACROSS NRN FLORIDA FOR AT LEAST THE NEXT
3-6 HOURS...WAVING A BIT IN LATITUDE. GIVEN THE MOISTURE AND
INSTABILITY CURRENTLY IN PLACE...AND THE REGIONS FAVORABLE
PLACEMENT WITH RESPECT TO A 50-60 KT UPPER JET OBSERVED VIA RAOB
AND GOES HD WIND DATA OVER SWRN GA...CONVECTION ACROSS NRN FL IS
FORECAST TO INCREASE AND LINGER WELL INTO THE OVERNIGHT HOURS. 

MANY OF THE LATEST HI-RES MODELS...INCLUDING THE PAST SEVERAL RUNS
OF THE HRRR AND EXPERIMENTAL HRRR...SHOW HOURLY RAIN RATES OF 2-3
IN/HR ACROSS NRN FL THROUGH 06Z. FARTHER SOUTH ALONG THE WRN
PENINSULA...ONSHORE 850-700 MB FLOW OF 20-30 KTS IS FORECAST TO
CONTINUE OVERNIGHT WHICH MAY ALLOW FOR LOCALLY HEAVY RAINFALL
TOTALS NEAR THE COAST...PRIMARILY WEST OF I-75. NARROW AREAS OF
TRAINING...SUCH AS WHAT WAS OCCURRING ACROSS WRN MARION COUNTY AT
00Z...MAY DEVELOP QUICKLY AND DROP 2-3 INCHES IN A SHORT TIME.
GIVEN ANTECEDENT RAINFALL RELATED TO HERMINE...FLASH FLOODING IS
POSSIBLE.

OTTO

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

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

LAT...LON   30888478 30798339 30668219 30398093 30138077 
            29828099 29648144 29568210 29108207 28578205 
            27938241 27758278 28208309 28888320 29248350 
            29538411 29538526 30368587 30818545