Area Forecast Discussion
Issued by NWS Portland, ME

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462 FXUS61 KGYX 150155 AFDGYX Area Forecast Discussion National Weather Service Gray ME 955 PM EDT Wed Mar 14 2018 .SYNOPSIS... Despite the worst of the storm being well to our northeast, the region remains under the influence of upper level low pressure. This is continuing on and off light snow over much of the area. That will pass this evening and overnight, and light accumulations are possible across New Hampshire and western Maine, and moderate accumulations possible in the mountains. This will gradually dry out overnight, and transition to snow showers in the mountains that linger into Friday. High pressure takes control for the weekend and fair but cool weather is expected. && .NEAR TERM /TONIGHT/...
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10PM UPDATE... Will drop the rest of the Winter Storm Warnings to Winter Weather Advisories considering the showery nature of the remaining snowfall. It is unlikely that warning level impacts are still being felt up there and forecast only calls for a few inches of snowfall overnight. 7PM UPDATE... Have updated the forecast based on latest conditions. Still seeing a decent coverage of snow showers this afternoon, though the intensity and coverage should wane this evening outside of the mountains where upslope conditions favor continued showers. Changed weather type from snow to snow showers to reflect the spotty and brief nature of most of this activity. Since most areas will not see more than an inch from this activity tonight, have decided to drop the Winter Weather Advisories. Most of the Winter Storm Warnings remain in place over the northern part of the area where more persistent showers could bring several more inches of snow mainly in the higher elevations. Have also lowered forecast lows tonight for some areas. Clouds will keep things from radiating well, but the deep snow pack should be enough to bring surface temperatures below freezing area wide, likely into the 20s. Any areas that break out of the clouds could drop further. ORIGINAL DISCUSSION... Tonight will feature a transfer from a synoptically driven snowfall event to more of an upslope event. Plenty of low level moisture, increasing west to northwest winds and the positioning of an upper level low overhead will allow for accumulating snows to continue. Winter storm warnings will remain in effect over the northern mountains. Elevation will play a role with the highest snowfall totals along areas above 1500 feet. Advisories will border the mountains where the foothills will receive accumulating snow as well. Further to the east, winter weather advisories will remain in effect over portions of interior southern Maine until 8 pm. Elsewhere, expect at least scattered snow showers overnight. There is also a possibility of a snow squall or two, mainly over northern areas. Ptype: There could be some rain mixing in over the Midcoast region through early this evening. Temperatures do not cool off much tonight with overnight lows mainly in the 20s.
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&& .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... 7PM UPDATE... Have updated Thursday high temperatures to lower the forecast a few degrees. MOS forecasts seem too high given the expected presence of cold core upper low affecting the region and continued deep snow pack. This was the case for much of last week as well when MOS forecasts were frequently 2-5 degrees too warm. 925MB temperatures indicate that sea level temps would reach about 42 degrees in full mixing. Given expected cloud cover, showers, and heat loss due to melting of the fresh snow pack, it should be pretty tough to reach 40 degrees. ORIGINAL DISCUSSION... A brief period of ridging aloft is expected over southern areas on Thursday, possibly bringing some sunshine to the downslope areas of southern New Hampshire and Maine. This will allow portions of the region to warm to 40 degrees or higher during the afternoon. Otherwise, expect snow showers to continue in the mountains. An upper level trough will allow for accumulating snow to continue in the mountains right through Thursday night. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Outside the flowers are blooming and birds are chirping. Somewhere. But not meteorological spring has yet to evict winter from the area. Upper low will be E of the area by Fri...leaving the region under Wly...moist low level flow. Upslope snow showers will continue thru the day...gradually scattering out into the evening. Surface ridging begins to nose into the region to start the weekend...gradually exerting more influence into early next week. It will be seasonably H8 temps pushing -20 C spill into Nrn zones. Temps should stay mainly in the 30s...with teens and colder overnight. Attention then turns to model guidance is in pretty good agreement at this long range for more precip. Trofing off the West Coast is forecast to eject into the central CONUS and initiate cyclogenesis. Though there are some differences in evolution...there is broad consensus for likely PoP Tue into Wed. There is significant spread in ensemble this is still 7 days this is a low confidence forecast...especially with any details. At this time deterministic and ensemble guidance is cold enough for snow...but at this time it could just as easily trend warm and W...or out to sea. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Short Term /through Thursday/...Areas of MVFR and locally IFR conditions over northern areas right through Thursday. Mainly VFR conditions over the southern downslope regions. Long Term...Generally VFR conditions expected thru the weekend. The exception will be Fri...and Wly upslope flow continues under upper low pressure. HIE may see SHSN and local IFR conditions in the vicinity...though by Fri more of the TEMPO variety. && .MARINE... Short Term...Have issued gales for the outer waters for tonight as winds continue to gust to 35 kt+. SCAs have been posted for the bays. Seas to gradually subside with time. Long Term...Wly flow lingering into Fri will likely keep SCA conditions going outside the bays. High pressure will slowly build in for early next week...allowing winds and seas to gradually diminish. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Weather Advisory until 6 AM EDT Thursday for MEZ007>009. NH...Winter Weather Advisory until 6 AM EDT Thursday for NHZ001>004. MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ151-153. Gale Warning until 6 AM EDT Thursday for ANZ150-152-154.
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&& $$ NEAR/SHORT TERM UPDATE...Kimble SHORT TERM...Cannon LONG TERM...Legro is the U.S. government's official web portal to all federal, state and local government web resources and services.