MESOSCALE PRECIPITATION DISCUSSION 0273
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
535 PM EDT WED AUG 13 2014
 
AREAS AFFECTED...ERN MA AND NH INTO SWRN ME 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 132134Z - 140300Z
 
SUMMARY...DESPITE DIMINISHING MOISTURE...FLASH FLOODING REMAINS A
CONCERN FROM ERN MASSACHUSETTS INTO MUCH OF NEW HAMPSHIRE AND SWRN
MAINE INTO EARLY TONIGHT. HOURLY RAINFALL OF 1-2 IN/HR WILL BE
POSSIBLE WITH TRAINING OF CELLS ALLOWING FOR 2 TO 4 INCHES LOCALLY.

DISCUSSION...AT 21Z...A RELATIVELY NARROW ZONE OF PRECIPITABLE
WATER EXCEEDING 1.5 INCHES AND 850 MB FLOW OF ROUGHLY 40 KTS
REMAINED IN PLACE OUT AHEAD OF A SURFACE LOW ANALYZED IN
CONNECTICUT BETWEEN HFD AND IJD. A CONVERGENCE ZONE OR WEAK
COASTAL FRONT EXTENDING NORTHEAST FROM THE LOW INTO SRN NEW
HAMPSHIRE AND WAS HELPING TO FOCUS LIFT AND HEAVY RAINFALL DUE TO
THE MODEST ONSHORE FLOW ALONG WITH SOME OROGRAPHIC ENHANCEMENT.
OBSERVED HOURLY RAINFALL RATES HAVE TOPPED OFF NEAR 1.5 IN/HR WITH
CONTINUED WARM RAIN PROCESSES AND WILL LIKELY CONTINUE THROUGH THE
REMAINDER OF THE EVENING.

AS A NEGATIVELY TILTED UPPER TROUGH AXIS CONTINUES TO SWING ACROSS
SRN NEW ENGLAND OVER THE NEXT SEVERAL HOURS...THE SURFACE LOW IN
CONNECTICUT WILL LIKELY TRACK ALONG THE CONVERGENCE AXIS INTO SERN
NEW HAMPSHIRE BY 03Z WHILE A ZONE OF 40-50 KTS 850 MB FLOW AND 1.5
INCH PRECIPITABLE WATER VALUES CLIPS COASTAL SECTIONS OF NEW
HAMPSHIRE AND SWRN MAINE. WHILE THE THREAT FOR FLASH FLOODING
CONTINUES TO DECREASE WITH THE DEEPEST MOISTURE MOVING OFF OF THE
CAPE PER RECENT BLENDED TPW IMAGERY...TRAINING OF HEAVY RAIN CELLS
OVER THE OUTLOOK AREA WILL CONTINUE A FLASH FLOOD THREAT THROUGH
03Z AT WHICH POINT THE DEEPEST MOISTURE WILL HAVE BEEN DISPLACED
EWD.

OTTO

ATTN...WFO...GYX...BOX...

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

LAT...LON   42187089 42207180 42627209 43427208 44087167 44677091
            44597017 44146977 43147010 42827028 42187089