MESOSCALE PRECIPITATION DISCUSSION 0806
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
453 PM EDT MON SEP 11 2017

AREAS AFFECTED...CENTRAL AND NORTHERN GA...SOUTHERN SC

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 112052Z - 120240Z

SUMMARY...THE RISK OF FLASH FLOODING WILL GENERALLY BE TO THE
NORTH AND NORTHEAST OF IRMA'S TRACK...WITH THE GREATEST RISK
SHIFTING INTO CENTRAL AND NORTHERN GEORGIA AND SOUTHERN SOUTH
CAROLINA.

DISCUSSION...SATELLITE IMAGERY CONTINUED TO SHOW DRY AIR WRAPPING
AROUND THE SOUTHEAST AND SOUTH SIDE OF IRMA...WHICH WAS BRINGING A
QUICK END TO RAINFALL SOUTH OF THE CENTER.  SATELLITE WAS ALSO
SHOWING A COOLING TREND IN CLOUD TOP TEMPERATURES TO THE NORTH AND
NORTHEAST OF THE CENTER OF IRMA.  THUS THE NORTHWARD TREND NOTED
IN PREVIOUS MPDS SHOULD CONTINUE INTO THE EVENING WITH PERSISTENT
RAIN BANDS BRINGING HIGH RAINFALL RATES TO AREAS OF CENTRAL AND
NORTHERN GEORGIA AND SOUTHERN SOUTH CAROLINA...WITH HEAVIEST RAINS
BEING FOCUSED ALONG THE COAST WHERE MOISTURE TRANSPORT IS
MAXIMIZED AND CAN INTERACT WITH A COASTAL FRONT.

RAIN BANDS CONTINUE TO REFIRE IN STRONG CONVERGENT FLOW...TAPPING
OFFSHORE INSTABILITY OF 1000-2000 J/KG CAPE. LOW LEVEL INFLOW IS
EXPECTED TO INCREASE DURING THE REMAINDER OF THE AFTERNOON AND
EARLY EVENING.  AS IRMA BEGINS TO TAKE A MORE WESTERLY COMPONENT
THESE RAIN BANDS WILL SLOW THEIR NORTHWARD PROGRESSION AND
POSSIBLY EVEN STALL. A STRONG COASTAL FRONT ACROSS SOUTHEAST
GEORGIA AND SOUTHERN SOUTH CAROLINA WILL FOCUS INTENSE RAINFALL
RATES ALONG THE COAST UNTIL STRENGTHENING LOW LEVEL FLOW CAN PUSH
THE COASTAL FRONT INLAND.

WHILE HI-RES MODELS ARE IN GOOD AGREEMENT WITH MAGNITUDE AND
PLACEMENT OF PRECIP OVER THE NEXT 6 HOURS. MORE MODEST RATES ARE
EXPECTED INLAND WHERE INSTABILITY WILL BE WEAKER....BUT COULD SEE
INCREASING THREAT AS LOW AND MID LEVEL FORCING INCREASES WITH THE
APPROACH OF IRMAS CIRCULATION.

BANN

ATTN...WFO...BMX...CAE...CHS...FFC...GSP...ILM...

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

LAT...LON   34228119 33557933 33177918 32078032 32208103
            32528214 32668307 32508502 34178485