Post by SKYSUMMIT on Sept 1, 2016 18:28:54 GMT -6
MESOSCALE PRECIPITATION DISCUSSION 0627
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
820 PM EDT THU SEP 01 2016
AREAS AFFECTED...WRN FL PANHANDLE INTO SRN AL/GA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 020017Z - 020615Z
SUMMARY...A THREAT OF FLASH FLOODING WILL INCREASE THROUGH 06Z
ACROSS THE CNTRL AND ERN FL PANHANDLE AND THE WRN PENINSULA AS
HURRICANE HERMINE NEARS THE COAST. AN ADDITIONAL FLASH FLOOD
THREAT IS EXPECTED FARTHER NORTH INTO SERN AL/SWRN GA WITH
RAINFALL RATES POSSIBLY EXCEEDING 3 IN/HR WHERE TRAINING BANDS
DEVELOP.
DISCUSSION...INFRARED SATELLITE IMAGERY OVER THE PAST THREE HOURS
HAS SHOWN A RAPID EXPANSION OF COLD CLOUD TOPS AROUND THE EYE OF
HURRICANE HERMINE WITH -70 TO -75C SOUTH OF THE EYE AS OF 2345Z.
AT 00Z...HERMINE WAS LOCATED ABOUT 45 MILES SSE OF APALACHICOLA
ACCORDING TO THE 00Z NHC ADVISORY...MOVING NNEWD AT 12 KTS.
REGIONAL RADAR IMAGERY SHOWED A WELL DEFINED EYEWALL ALONG WITH A
COUPLE OF SPIRAL BANDS ROTATING ENEWD INTO THE CNTRL/NRN FL GULF
COAST. LOCAL OBSERVATIONS HAVE MATCHED DUAL POL RAINFALL RATES OF
0.5 TO 1.0 IN/HR SO FAR...WHICH IS WELL BELOW CURRENT FFG VALUES
OF 3+ IN/HR.
HOWEVER...AS HERMINE CONTINUES TO APPROACH THE FL
PENINSULA...INTENSE RAINFALL WITHIN THE EYEWALL SHOULD IMPACT
LOCATIONS AS FAR WEST AS APALACHICOLA TO AS FAR EAST AS PERRY.
DESPITE THE STEADY FORWARD PROGRESSION OF HERMINE...PERIODS OF
TRAINING MAY ALLOW FOR RAINFALL RATES EXCEEDING 3 IN/HR IN A FEW
ISOLATED LOCATIONS IN THE FL PANHANDLE. FARTHER EAST...LOW LEVEL
CONFLUENCE TO THE EAST OF HERMINE HAS THE POTENTIAL TO STALL A
NARROW AXIS OF HEAVY RAINFALL WITHIN ONE OF THE OUTER BANDS OF
HERMINE...FROM NEAR TAMPA TO LAKE CITY. ANY STALLING OF ONE OF
THESE BANDS EASILY HAS THE POTENTIAL TO EXCEED RAIN RATES OF 3
IN/HR.
ANOTHER AREA WORTH NOTING IS ACROSS SERN AL INTO CNTRL GA. RECENT
RUNS OF THE RAP/HRRR HAVE CAUGHT ONTO THE IDEA OF AN AXIS OF LOW
LEVEL CONVERGENCE STRENGTHENING FROM NEAR MCN TO ECP. THIS IS
ALREADY SEEN IN LOCAL VAD WIND PLOTS...WITH A FORECAST SLOW DRIFT
WWD THROUGH 06Z. AN AXIS OF HEAVY RAINFALL MAY DEVELOP IN THIS
AREA OF CONVERGENCE WITH THE POTENTIAL TO CAUSE LOCAL RUNOFF
ISSUES.
OTTO
