MESOSCALE PRECIPITATION DISCUSSION 0193
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 AM EDT SAT MAY 06 2017

AREAS AFFECTED...SOUTHEAST MAINE

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 060745Z - 061345Z

SUMMARY...APPROACH OF SHORTWAVE AND SFC FRONTAL INFLECTION POINT
WILL LEAD TO INCREASED RATES UP TO 1"/HR TOWARD 08-09Z WITH 3-6HR
TOTALS OF 2-3" MAY EXCEED FFG POSING FLOODING CONCERNS WITH FLASH
FLOODING POSSIBLE.

DISCUSSION...LOCAL OBSERVATIONS ACROSS SOUTHEASTERN MAINE INDICATE
OVER RUNNING PRECIPITATION OF .5-.8" HAVE FALLEN.  RADAR MOSAIC
FROM BOX/GYX SUGGEST EMBEDDED SHORTWAVE AND SURFACE REFLECTION ARE
APPROACHING FROM THE SW A BIT FASTER THAN MODELS PROGGED
SUGGESTING THE WAVE REACHES BHB AROUND 830Z.  AHEAD OF THE WARM
FRONT LOWERING CLOUD BASES AND INCREASED MST FLUX FROM
STRENGTHENING 850MB FLOW FROM SELY 45KTS VEERING TO 60KTS WITH
WARM FRONT PASSAGE AND TPWS INCREASING FROM 1.5 TO 1.75" BY 10Z
WITH POSSIBLE 100-250 J/KG CAPES (PER HRRR) WILL SUPPORT INCREASED
RAIN RATES TO UP TO 1"/HR FOR AN HOUR OR SO...ALLOWING 3HR TOTALS
TO NEAR FFG VALUES OF 1.5" IN THE VICINITY. 

LONGER TERM...EVEN AS THE WARM FRONT PASSES...THE COLD FRONT IS
EXPECTED TO REMAIN FAIRLY CLOSE TO OR PARALLEL TO INTO THE WESTERN
BAY OF FUNDY.  LARGER SCALE UPPER LEVEL CYCLONE WILL DRAW S/W
CONTINUING TO SLOW/STALL OR EVEN POTENTIALLY RETROGRADE THE COLD
FRONT ALONG THE COAST.  THOUGH WITH INCREASED FLOW AT THE SURFACE
UP TO 40KTS AND 850MB FL UP TO 65KTS  IN AND AROUND THE FRONT
SUPPORTING CONTINUED MODERATE RAINFALL OF .25"/HR LIKELY WITH
OCCASIONAL HIGHER SHORT-TERM BURSTS SUPPORTED BY DOWNSTREAM
BLENDED RAIN RATE PRODUCTS FROM POLAR MICROWAVE SATELLITE SUITE. 
AS SUCH HI-RES GUIDANCE SUGGESTING MAGNITUDES OVER 2-3" THROUGH
15Z SEEM REASONABLE FOCUSING ON EASTERN WASHINGTON COUNTY INTO SW
NEW BRUNSWICK MAINTAINING FLOODING CONCERN THROUGH THE MORNING
HOURS.
GALLINA

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

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

LAT...LON   45696765 45236702 44676696 44276798 44026842
            43996872 43996885 44286893 44876843 45366800