Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 122052 AFDGYX Area Forecast Discussion National Weather Service Gray ME 452 PM EDT Thu Oct 12 2017 .SYNOPSIS... High pressure will remain over the region tonight and will shift east on Friday. A cold front will approach from the west Friday night and will drop south into northern New England on Saturday. The front will lift north as a warm front Saturday night. Low pressure will track east through southern Canada on Sunday and will drive a trailing cold front through the region Sunday night. High pressure will build in from the west on Monday and will shift offshore on Tuesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Update...Refreshing the next few hours based on the latest observational trends. Also sped up the timing of temp drop tonight. Strong high pressure in place and dry NE flow has established itself across the region. With rising heights aloft and H8 temps rising a few degrees...this will only help to promote low level inversion development above the boundary layer. I expect strong radiational cooling to take place after dark...and despite the relatively warmer H8 air...widespread 30s and some 20s across the forecast area. I would not be surprised to see MWN have one of the warmer low temps in this type of shallow inversion set up. Previous discussion...High pressure will allow for clear skies and light winds overnight. This will set the stage for significant radiation cooling with low dew point values over the region. Areas of frost are expected, mainly away from the coast. Further to the north, northern Grafton and northern Carroll counties can expect a hard freeze, therefore, freeze warnings will be hoisted for that region. The remainder of the mountains and foothills have already ended their growing season where overnight lows will only be in the 20s. Areas of fog will develop late tonight as surface temperatures approach the dew point values.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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The surface ridge will continue to slowly ease offshore on Friday. This will set up a southeasterly gradient along the coast where readings once again will top out near 60 degrees. Further inland, a slight moderating trend will begin with readings in the lower to mid 60s. Clouds will increase and thicken Friday night as a weak front approaches from the west. There may also be some low cloudiness coming in off the Gulf of Maine during this period. There will also be a low chance for a shower Friday night, however neither forcing or moisture supply appears to be rather insignificant.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/... High pressure well off the coast will allow a warm southwest flow to develop bringing warming temperatures and increasing humidity Saturday through Sunday. Coastal areas along the midcoast may have cooler temps due to possibly a more southerly flow off the waters. A weak frontal system tries to push south toward the mountains and central areas of Maine but stalls...clouds and light showers may develop along this front in those areas Sat and Sat night. This front system gets pushed further north by Sunday as a warm front in advance of a strong upper trof and associated cold front that will be approaching from the west. With the warm front moving northward Sunday, temps will reach the 70s across southern areas with dew points in the mid 60s. The upper trof and associated cold front will move rapidly across the region Sunday night setting off scattered showers. A large Canadian ridge of high pressure builds into the region Monday with significantly cooler temperatures and a return to mostly sunny skies. Tue into Wed seasonable temperatures and fair weather expected except maybe a few mountain showers late Tue and Tue night as a trof moves across southern Canada skirting the area. Generally stayed close with superblend model guidance for the outlook period. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... Short Term...Mainly VFR except for patchy inland valley fog and perhaps a brief period of IFR/LIFR conditions late tonight especially at KLEB. Long Term... MVFR conditions possible in widely scattered mountain showers Saturday into Sunday with mainly VFR conditions expected across southern areas. MVFR to IFR conditions associated with a cold front in the mountains late Sunday will move southeast to the coast overnight Sunday night. VFR conditions return Monday...except possibly MVFR in the mountains. Gusty northwest winds expected Monday. && .MARINE... Short Term...Seas will continue to slowly subside. Therefore, expect conditions to remain below SCA thresholds. Long Term...SCAs likely Sunday and Sunday night in southwest flow ahead of a cold front. SCAs Monday in the northwest flow behind front. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Frost Advisory from 2 AM to 8 AM EDT Friday for MEZ018>022. NH...Frost Advisory from 2 AM to 8 AM EDT Friday for NHZ005>013-015. Freeze Warning from 2 AM to 8 AM EDT Friday for NHZ003-004. MARINE...None. && $$ NEAR TERM...Legro

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