MESOSCALE PRECIPITATION DISCUSSION 0065
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1107 PM EDT FRI MAY 16 2014
 
AREAS AFFECTED...ERN NY...VT...CN...RI...WRN MA...WRN NH 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 170306Z - 170806Z
 
SUMMARY...FOCUSED ASCENT WILL PRODUCE A CONVECTIVELY ENHANCED RAIN
SHIELD WITH VERY SLOW EASTWARD MOVEMENT OVERNIGHT. NUMEROUS
LOCATIONS WILL RECEIVE MORE THAN 2 INCHES OF RAIN AND LOCAL TOTALS
OVER 3 ARE POSSIBLE. THIS COULD YIELD FLASH FLOODING IN THE MOST
SUSCEPTIBLE LOCATIONS.

DISCUSSION...A WELL DEFINED SHORTWAVE WAS APPROACHING THIS REGION
WHILE STOUT SOUTHERLY WINDS IN THE LOW LEVELS FED PW VALUES OF 2.0
TO 2.5 STANDARD DEVIATIONS ABOVE NORMAL OFF THE ATLANTIC. THE
HI-RES MODELS ARE UNANIMOUS IN PAINTING A SWATH OF 1.5 TO 2.5 INCH
AREAL AVERAGE RAINFALL ORIENTED SOUTH TO NORTH THROUGH THE AREAS
BORDERING EASTERN NY. SUSPECT THIS WILL OCCUR AS A BAND OF FOCUSED
850-500 MB ASCENT MAKES USE OF SUFFICIENTLY STEEP LAPSE
RATES...PER REGIONAL SOUNDINGS...TO YIELD AN EXPANDING RAIN SHIELD
AND LEADING LINE CONVECTION.

HEAVY RAIN WILL TRAIN NORTHWARD WITHIN UNIDRECTIONAL DEEP LAYER
FLOW...WHILE PROPAGATION VECTORS ARE EAST AT ONLY 5 TO 10 KNOTS.
WINDS WILL GRADUALLY VEER AS THE WAVE APPROACHES...PUSHING THE
HEAVY RAIN THREAT TOWARD NH/RI/CENTRAL MA BY 08-09Z. SOME OF THE
HEAVIER RAIN RATES...AROUND 1.5 INCH PER HOUR...MAY OCCUR WITH
CONTRIBUTIONS FROM LOW LEVEL UPSLOPE INTO THE MOUNTAINS IN
NY/VT...AND WHERE INSTABILITY IS GREATER...NEAR 250 J/KG OR MORE
PER THE HRRR...IN COASTAL NY/CT/RI.

BURKE

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

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

LAT...LON   40387385 40687399 41677390 42827376 43617361 44477332
            45137294 45277243 44877196 43627185 42577161 41807128
            41177132 40537190 40237307 40387385