MESOSCALE PRECIPITATION DISCUSSION 0350
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 PM EDT SUN SEP 07 2014
 
AREAS AFFECTED...PORTIONS OF THE CAROLINAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071900Z - 080100Z
 
SUMMARY...THUNDERSTORMS ARE INCREASING IN COVERAGE WITHIN AN
UNSTABLE AIR MASS NEAR A SLOWLY PROGRESSIVE COLD FRONT.  HOURLY
RAIN RATES UP TO 2.5", WITH LOCAL AMOUNTS OF 3-5", SHOULD LEAD TO
FLASH FLOODING.

DISCUSSION...A BROAD AREA OF THUNDERSTORMS HAS FORMED NEAR AND
AHEAD OF A SLOWLY PROGRESSIVE COLD FRONT.  PRECIPITABLE WATER
VALUES ARE 2-2.25" ACROSS THE REGION, ABOVE THE 90TH PERCENTILE
FOR EARLY SEPTEMBER.  LOW-LEVEL INFLOW 10-15 KTS, WHICH NORMALLY
IMPLIES SINGLE CELL/PULSE CONVECTION.  HOWEVER, THE 0-6 KM BULK
SHEAR IS NEAR 25 KTS, WHICH IS ATTEMPTING TO ORGANIZE THE
CONVECTION.  MIXED LAYER CAPES ACROSS THE REGION ARE IN THE
1000-2000 J/KG RANGE DUE TO DAYTIME HEATING. 

DEEP UNIDIRECTIONAL WEST-SOUTHWESTERLY FLOW IS SEEN IN AREA
SOUNDINGS, FAVORABLE FOR HEAVY RAINFALL AND CELL TRAINING.  THE
NEARBY FRONTAL ZONE, 850 HPA TROUGH AXIS, AND SEA BREEZE
BOUNDARIES SHOULD ACT AS FOCI FOR CONVECTION.  WHILE MINIMAL
LOW-LEVEL INFLOW EXISTS, CELL MERGERS AND/OR TRAINING COULD LEAD
TO LOCALLY HEAVY RAINFALL.  CONVECTION COULD BE OUTFLOW DOMINANT;
IT IS POSSIBLE THE THREAT FOR EXTREME SOUTHEASTERN NC NEAR
WILMINGTON HAS LOWERED FOR THE TIME BEING DUE TO CAPE BEING
LOWERED BY MORNING AND EARLY AFTERNOON THUNDERSTORMS. 
SYNOPTICALLY, THIS SITUATION IS REMINISCENT OF THOSE FROM JULY
21ST AND AUGUST 10TH, WHEN LOCAL AMOUNTS OF 5-8" OCCURRED IN THIS
REGION.  HOURLY RAIN RATES UP TO 2.5", WITH MESOSCALE GUIDANCE
GENERALLY INDICATING LOCAL AMOUNTS OF 3-5", SHOULD LEAD TO FLASH
FLOODING. 

ROTH

ATTN...WFO...AKQ...CAE...CHS...GSP...ILM...MHX...RAH...

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

LAT...LON   35897699 35777534 35387539 35147550 35027601 
            34687637 34577654 34577711 34207771 33897801 
            33627895 32997928 32578041 33048084 34138172 
            35257941