MESOSCALE PRECIPITATION DISCUSSION 0408
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
527 AM EDT WED OCT 08 2014
 
AREAS AFFECTED...SRN AND ERN ME 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 080927Z - 081327Z
 
SUMMARY...TRAINING OF LOW-TOPPED CONVECTION WILL YIELD ISOLATED
2-INCH RAIN TOTALS AND MAY LEAD TO FLASH FLOODING THROUGH 13-14Z.

DISCUSSION...RADAR TRENDS SHOWED PRONOUNCED TRAINING BEGINNING TO
TAKE PLACE...AND EXPANSION OF THE OVERALL RAIN SHIELD ASSOCIATED
WITH LOW-TOPPED CONVECTION IN AN ENVIRONMENT MARKED BY MOST
UNSTABLE CAPE VALUES OF 500 TO NEAR 1000 J/KG. THE HRRR FORECASTS
SIMILAR OR SLOWLY DIMINISHING BOUYANCY THROUGH ABOUT 13Z...WHILE
AT THE SAME TIME THE RAP FORECASTS MAINTENANCE OR STRENGTHENING OF
BOTH MID LEVEL ASCENT AND LOW LEVEL INFLOW...WITH MAINE BEING
POSITIONED BENEATH THE INFLECTION POINT OF THE UPPER FLOW.

CELL MOTION REMAINS ALIGNED WITH CORFIDI VECTORS FOR FORWARD
PROPAGATING SYSTEMS THROUGH AT LEAST 13Z...SUGGESTING A PROLONGED
PERIOD OF TRAINING...MOST LIKELY TO REMAIN ALONG THE AXIS THAT HAD
ALREADY REVEALED ITSELF NEAR AND EAST OF I-95. THE MESOSCALE
MODELS WERE NOT STRONGLY SUGGESTIVE OF A FLASH FLOOD EVENT...BUT
THE CANADIAN REGIONAL MODEL DID PLACE SWATHS OF 1.25 INCH AREAL
AVERAGE AMOUNTS HERE...AND THE HRRR HAD SPOTTY HEAVIER AMOUNTS
DISPLACED WEST OF THE CURRENT TRENDS.

DUAL-POL RAINFALL ESTIMATES INDICATED SPOTTY 1 TO 1.25 INCH PER
HOUR ACCUMULATIONS OWING TO TRAINING. THE THREE HOUR FLASH FLOOD
GUIDANCE IN SOUTHERN ME IS NEAR 2 TO 2.5 INCHES. THE NORTHERN
EXTENT OF HEAVY RAIN MAY REACH THE LATITUDE OF MILLINOCKET WHERE
FFG VALUES ARE SLIGHTLY LOWER. IN ANY CASE...THERE IS SOME
ENHANCED RISK OF FLASH FLOODING...ESPECIALLY CLOSER TO THE HEART
OF THE INSTABILITY AXIS...NEAR AND JUST INLAND FROM THE COAST.

BURKE

ATTN...WFO...CAR...GYX...

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

LAT...LON   46296748 45576707 44306831 43236944 43107019 
            43787036 45126979 46186871