Area Forecast Discussion
Issued by NWS Portland, ME

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112 FXUS61 KGYX 251118 AFDGYX Area Forecast Discussion National Weather Service Gray ME 718 AM 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 today through tonight...reaching Cape Cod by Friday morning. Low pressure will continue northeast into the maritimes Friday 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 /UNTIL 6 PM THIS EVENING/...
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700 AM Update... Rain continues to push north through southern New England early this morning and is generally on track with current forecasts. Expect rain to shift into southern New Hampshire over the next couples of hours and into central New Hampshire and southwest Maine by late morning. Have adjusted temps/tds/rh grids based on latest obs. No other changes planned attm. Previous discussion.... Broad area of low pressure from the Ohio Valley through the mid Atlantic states will lift a warm front northward today. HRRR generally in line with latest radar composite and brings precip into southern New Hampshire and southwest Maine by late morning to early afternoon. This preliminary batch of precip will continue north through the afternoon hours. Only looking for light QPF through this evening with amounts of a quarter inch or less. Onshore flow will quickly pick up this morning with easterly winds becoming gusty by afternoon. High temperatures will only make the mid to upper 50s in coastal and southern interior sections. Farther north...highs will edge into the lower 60s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Just looking for showery precip this evening with some additional light accumulations. Strong vort lobe rotating around upper trough back over the Ohio valley will swing north toward the region after midnight and will bring a shot of moderate to occasionally heavy rain back into the region during the early morning hours and through the day on Friday. Expect rain to taper to showers by Friday evening. Most of the forecast area will see an inch to an inch and a half with locally 2 inches in coastal areas. Long duration of this event should preclude any flooding issues but poor drainage areas may see some brief issues in heavier rainfall Friday. Expect temperatures to show little change Thursday night and Friday with lows Thursday night in the near 50 and Highs on Friday in the 50s to near 60. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... 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 /11Z THURSDAY THROUGH MONDAY/... Short Term...IFR/LIFR ceilings developing today and persisting through Friday. 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 SCA`s through Friday morning. 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 from 2 PM this afternoon to 2 PM EDT Friday for ANZ151-153. Small Craft Advisory from 11 AM this morning to 2 PM EDT Friday for ANZ150-152-154. && $$

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