Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 160424 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1124 PM EST Fri Dec 15 2017 .SYNOPSIS... Weak low pressure to our north and south will provide clouds, and maybe a few snow showers or flurries tonight into early Saturday. High pressure builds in on Sunday, for a pleasant, but chilly day. Two weak waves will move through early next week bringing some rain and snow showers, as well as some warmer air. It cools down again toward the end of the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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1115 pm Update: Have adjusted POPs along the coastal and some interior portions and based POPs off radar and then interpolated some the slow progress to the east based off the trajs aloft. The developing weak inverted offshore surface trof has made enough west progress to shift a band of light snow to coastal and interior portions. Some places along the midcoast may see around a half inch or so with generally a dusting over most other areas. Also made some adjustments to increase POPs over the mountains overnight as guidance suggests scattered showers to move across area after midnight. Other than those changes input obs data and minor tweaks to temps and winds. 1025 PM Update...Have increased PoPs a little bit for the next few hours on the coastal plain based on latest observational data. Short wave trough and low level convergence zone acting to aid in the development of a little light snow on the coastal plain (PWM, SFM, etc). This should shift northeastward and mainly focus on the mid coast after midnight. However, a dusting of snow will be possible outside of the mid coast through 1 am or so. Otherwise, no further changes. 925 PM Update...Have made some slight changes in PoPs for the overnight hours. Latest mesoscale model data and radar imagery indicate that a weak convergence zone just offshore (weak NORLUN trough) may bring a little light accum snow to areas northeast of PWM...mainly the mid coast. Have increased PoPs a little bit in those areas (especially the islands and necks) with an inch or less accumulation. Otherwise, have chancy snow showers further inland that shouldn`t last too long, re: 6sm -sn at DAW and SFM this hour. This light snow or flurry activity may continue to move northward over the next few hours with little to no accums expected. 535 PM Update...Little change to the going forecast other than lowering temperatures for the next several hours based on observational trends. Otherwise, some snow showers are expected in the far interior tonight in association with a short wave trough. In addition, a more southern short wave trough could allow some snow showers to graze southernmost and easternmost zones tonight as well. The rest of the region should expect cloudy conditions with perhaps a few flurries. Winds will be light this evening. Previously... Expect increasing clouds tonight as a pair of shortwave troughs pass through the area, one to the south and one to the north. The one to the south is already producing light snow over southern New York and moving into southern New England. Have included mainly slight chance PoPs for this light snow as it could bring a few flakes to southern New Hampshire and coastal Maine overnight. Further to the north, another wave will bring increasing clouds and perhaps a few mountain snow showers overnight and into tomorrow morning. With cloud cover widespread tonight, expect lows in the teens and single digits.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Slightly warmer air makes a brief appearance on Saturday ahead of an approaching cold front. Temperatures may rise into the 30s in southern and coastal areas. Upslope snows continue in the mountains as the front arrives. Drier air moving in with high pressure Saturday night should bring the upslope snows to an end with temperatures falling back into the single digits and teens again, but a few degrees colder than tonight. && .LONG TERM /SUNDAY THROUGH FRIDAY/... At 500 mb, flow becomes fast and zonal through a good part of next week along much of the US/Canada border, with several fast-moving and weak waves moving through New England. So for the most part there will be some threats for precip /but no significant storms/, with temps moderating mostly to near or a little above normal. Sunday will see surface ridge over the region shifting east. The day should start sunny with high clouds thickening late. Sunday will likely be the coldest day in the long range with highs in the 20s. Sunday night will see approach of the first of several waves, and this one will be weak with little dynamic forcing, and lots of low level dry air, so, it could produce a round of snow showers starting late Sunday night, into Monday. Highs on Monday look to be a few degrees warmer than Sunday but still in the 20s, except low 30s in SE NH. The one thing this system will do is allow warmer air in from the SW behind it. So although another wave quickly follows on its heels for Tuesday, temps will rise into the 30s and low 40s on Tuesday with a threat of snow or rain showers, mainly in the mountains. This system will push a cold front through Tue night. Wednesday looks cooler with upslope SHSN in the mtns, and highs in the upper 20s N to mid to upper 30s in the south, and Thu will likely be a little cooler with surface ridge overhead, light winds and little mixing, with highs in the 20s to low 30s. Friday may end up dry, but another system approaches from the west which could affect late Friday into Saturday. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Short Term...VFR expected for the most part with light winds. However, MVFR conditions in light snow are possible on the coastal plain tonight, especially on the mid coast. Any snow should be fairly light. Long Term...Mainly VFR Sunday through Wed, although could see tempo flight restrictions in SHSN Monday, and SHRASN on Tue. && .MARINE... Short Term...Although winds are light now, a cold front will drop through and bring stronger winds by morning, with advisory conditions expected on Saturday. Long Term...Winds/seas relatively tranquil Sunday through Tuesday, but may need SCA by Tue night into Wed. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 6 AM to 11 PM EST Saturday for ANZ150-152-154. && $$ NEAR TERM...Marine SHORT TERM...Marine LONG TERM...Hanes

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