MESOSCALE PRECIPITATION DISCUSSION 0271
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
111 PM EDT WED AUG 13 2014
 
AREAS AFFECTED......PORTIONS OF VT/NH/MA/CT... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 131711Z - 132111Z
 
SUMMARY...FLASH FLOODING INCREASING PROBABLE THIS AFTERNOON AS
RAIN RATES AND DURATION INCREASE.

DISCUSSION...THE WEAKENING PHASE OF THE RAIN SYSTEM THAT AFFECTED
LONG ISLAND AND SOUTHERN CT THIS MORNING HAS ENDED.  SEVERAL HOURS
OF INSOLATION AND GRADUAL APPROACH OF COOLER MID LEVEL
TEMPERATURES HAVE HELPED TO DESTABILIZE AREAS TO THE WEST AND
SOUTH OF A PRIMARY SURFACE OVER WESTERN CT THAT INCLUDES A LINE OF
MESOLOWS EXTENDING INTO SOUTHERN VT...RESULTING IN AVERAGE CAPES
OF 400-1000 J/KG.  WITH THE BOUNDARY LAYER GRADUALLY DEEPENING AND
ENTRAINING SOME OF THIS AIR...THE CONVECTIVE ELEMENTS THAT ARE
BECOMING INCREASINGLY EVIDENT ON VISIBLE SATELLITE IMAGERY AND
RADAR ARE EXPECTED TO STEADILY INCREASE THROUGH THE AFTERNOON.

GIVEN THE CURRENT ORIENTATION OF BOUNDARY LAYER
FEATURES...INSTABILITY...AND TERRAIN...ALONG WITH HI-RES
GUIDANCE...THE MOST LIKELY AREA TO RECEIVE THE HEAVIEST RAIN
THROUGH THE AFTERNOON EXTENDS IN A NARROW CORRIDOR NORTHEAST OF
THE PRIMARY SURFACE LOW THEN BUMPING AGAINST THE EASTERN FACING
SLOPES OF THE BERKSHIRES AND WHITE MOUNTAINS.  

GIVEN THE AVAILABLE MOISTURE AND INSTABILITY PROFILES AS WELL AS
VERTICAL CHANGES IN WIND...RAIN RATES SHOULD AVERAGE JUST OVER 0.5
INCHES PER HOUR BUT WILL BE CAPABLE OF REACHING ABOUT 1.25 INCHES
OR MORE NEAR THE MESOLOWS AND IN VICINITY OF TERRAIN...WHICH COULD
LEAD TO FLASH FLOODING IF THE RAIN PERSISTS FOR MORE THAN 2 HOURS.

JAMES  

ATTN...WFO...GYX...BOX...BTV...ALY...

ATTN...RFC...NERFC...

LAT...LON   41727320 42517315 43697242 44447160 44257089 43327108
            42367171 41757239 41727320