Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 251850 AFDGYX Area Forecast Discussion National Weather Service Gray ME 250 PM EDT Thu May 25 2017 .SYNOPSIS... A broad area of low pressure from the Ohio Valley through the mid Atlantic coast will slowly lift northeast tonight...reaching Cape Cod by Friday morning. Low pressure will continue northeast into the maritimes through Friday night. Weak high pressure will build over the area on Saturday and will shift offshore on Sunday. Weak low pressure over the eastern Great Lakes will lift north into western Quebec Sunday night and will drive a cold front toward the region on Monday. The front will slowly cross the area Late Monday night and Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Higher pressure and easterly winds have kept much rain from intruding into northern New England by retarding the advancement of precipitation into Maine and northern and central NH until the last couple of hours. The flow has intensified along the coast as the pressure gradient increases/low pressure nears. Temperatures have been kept down in this marine airmass while northern sections were able to break out into the 60s. CAM models have been correct in showing a weakness this afternoon in precipitation fields over NH and especially Maine as energy diverges both towards northern NY State as well as offshore. We`ll see a break in most shower activity more or less this afternoon and evening...however there will be widely scattered showers still around...mainly over the mountains. Around midnight a stronger short wave associated with this system will pivot into the area and precipitation will increase both in intensity and areal coverage. This is when we will see the bulk of the 1-2 inches with this event. We`ll see some heavy downpours for the overnight period into Friday morning. Winds are picking up as mixing deepens today and expect ESE winds to gust to 25 kt through the night. Continued with drizzle tonight mainly in between the two systems as the onshore flow intensifies. Lows will be in the upper 40s to around 50. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... After the heavier rain expected during the morning hours...precipitation tapers off to showers by Friday afternoon. Again the heavier rain will be along the coast with some enhancement over terrain. The long duration of this event should preclude any flooding issues but poor drainage areas may see some brief issues in heavier rainfall that occurs through tomorrow. Expect temperatures to warm only about 5-10 degrees from overnight lows tonight to highs Friday. Tomorrow night clouds will begin to decrease across the region. The upper low will be engulfed in another circulation south of Greenland while the surface cyclone fills. Overnight lows Friday night will drop farther in a drier airmass with lows in the 40s most locations and perhaps up to 50 degrees in warm spots. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Trof will be lifting out Fri night into Sat. Lingering low level moisture should keep clouds and possibly fog around overnight. Clouds will gradually clear out later Sat though as weak s/wv ridging moves across the region. That brief ridge will depart Sun...allowing the next s/wv trof to drive a warm front Nwd thru the Northeast. Models remain consistent with low pressure forming well out to sea along the triple point...which may spare the region another widespread moderate rainfall event. However upper trofing is forecast to remain persistent for the remainder of the work week. Lower heights and cyclonic flow will favor afternoon increases in clouds and chances for showers. Temps will more or less be near normals. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Short Term...IFR/LIFR ceilings developing today and persisting through tomorrow. ESE winds will gust to 25 kts most terminals through tomorrow. Early on LLWS will affect HIE and LEB tonight. Drizzle and fog will affect most TAF sites outside of HIE and LEB tonight before the moderate to heavy rain arrives. Long Term...Lingering low level moisture may keep some MVFR CIGs around Fri night. Daytime heating into Sat should allow any remaining MVFR conditions to lift. Weak ridging should hold thru Sun...allowing for VFR conditions. The next s/wv trof arrives Mon...and scattered MVFR conditions in SHRA or maybe even a TSRA return. && .MARINE... Short Term...Continuing SCAs through Friday afternoon. At that point we may need a SCA just for high seas for the outer waters. Long Term...Winds and seas gradually diminish as weak high pressure moves over the waters. Developing Sly flow over the waters by Mon may bring some 5 ft seas outside of the bays. && .TIDES/COASTAL FLOODING... Highest astronomical tides of the year on tap for tonight and Friday night. Have issued a Coastal Flood Advisory for all coastal zones for around the time of high tide tonight. Forecast tide will reach 12 feet in Portland and with a storm surge of .3 to .5 feet will likely see splash-over and flooding of the usual spots around the time of high tide around 1230 AM tonight. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT Friday for MEZ023>028. NH...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT Friday for NHZ014. MARINE...Small Craft Advisory until 2 PM EDT Friday for ANZ150>154. && $$ NEAR TERM...Hanes SHORT TERM...Hanes LONG TERM...Marine is the U.S. government's official web portal to all federal, state and local government web resources and services.