Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 181939 AFDGYX Area Forecast Discussion National Weather Service Gray ME 339 PM EDT Mon Mar 18 2024 .SYNOPSIS... Cyclonic flow this week promotes breezy west-northwest flow, temperatures trending cooler toward seasonal averages, and light snow and rain showers driven by instability. Showers will be mostly confined to the mountains, however, a quick-hitting clipper will likely bring more widespread showers all the way to the coast Wednesday into Thursday. Cool high pressure returns late in the week, with a low potential for another system this weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Visible satellite imagery this afternoon shows a plethora of diurnally driven and upslope clouds across the region with Northeast radar mosaic showing some weak returns, mainly over the mountains. Current temperatures range from the 30s across the north to the middle 40s in southern NH and southwestern ME. It will continue to be a partly cloudy afternoon with a few scattered flurries and sprinkles. After some initial clearing this evening, clouds will be on the increase again overnight as a shortwave trough and associated cold front drop south over New England. Scattered snow showers will remain possible through the night but they will be mainly confined to the far north and mountains. Low temperatures will range from around 20 across the north to the lower 30s in southern NH and coastal southwestern ME. Locally colder readings will be possible wherever winds decouple and skies remain more clear.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
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The upper level pattern will become more zonal in nature on Tuesday as sfc high pressure builds to our south and west. Similar to today, daytime heating will allow for the development of a cumulus field during the afternoon but moisture depth does not look very deep as afternoon mixing helps to dry out the lower and mid-levels. As a result, despite these clouds, any scattered flurries will be limited in scope and confined to the higher terrain... especially early in the day. Highs will range from the 30s across the north to the middle 40s south. It will remain a little breezy with west-northwest gusts up to around 25 mph, which will make it feel a little cooler. Tuesday night will feature increasing clouds ahead of a weak system that will be approaching from the west. There will also be an increasing chance for scattered snow showers after midnight, especially over western NH. Lows will range from the upper teens to upper 20s from north to south.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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An Alberta Clipper will cross the region to start out the long term portion of the forecast. This will bring snow showers or a period of steady snow to northern portions of the forecast area Wednesday with temperature profiles supporting rain showers over southern sections. This system will likely lead to redevelopment along the Maine coastline Wednesday night. Cold air advection will develop on the back side of this system. This will change any leftover liquid precipitation back over to snow during the night. Some icy locations may develop with morning lows in the 20s in the north and near 30 degrees in the south by morning. The low pressure system will continue to undergo intensification on Thursday as the surface low exits through the Canadian Maritimes. Winds will become aligned through an increasing layer in a full cold air advection mode. Bufkit profiles suggest wind gusts up to 40 kt will be possible during the day with higher gusts over the mountains and hilltops. It will be chilly with highs only in the 20s north to the 30s south. It will also be very dry with low surface dew points during this period. Have forecast on the lower spectrum of guidance in terms of the dry air advecting over the region in addition to the influence of downslope drying. Windy and cold conditions will continue Thursday night. Have increased pops for the mountains where upslope snow showers will be continuing. High pressure will build into New England from Canada on Friday with cold and dry air remaining over the region. This sets the stage with rain and snow possible over the weekend. Models continue to struggle with the timing and placement of an area of low pressure ejecting out of the southeastern United States. In any case, additional precipitation would be tacked on to our wettest start to the month of March in Portland.
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&& .AVIATION /17Z MONDAY THROUGH FRIDAY/...
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Short Term...VFR conditions expected with WNW winds prevailing. Gusts up to around 25 kts will remain possible through 00Z Tuesday and again from 14Z-00Z Wednesday. The exception will be at KHIE where MVFR ceilings are likely tonight through early Tuesday. No LLWS is expected. Long Term...Lowering ceilings and precipitation in the form of rain and snow showers will enter the region on Wednesday. Conditions will lower to IFR in most areas, especially northern areas which may have a period of steady snow along with areas of LIFR conditions. These conditions continue Wednesday night as low pressure develops near the Maine coastline. VFR conditions expected outside the mountains on Thursday and Thursday night. A tight west to northwest gradient will lead to very gusty winds in a cold air advection pattern with wind gusts up to 40 kts possible. Windy conditions will continue Thursday night with some upslope snow showers remaining across the upslope facing higher terrain. VFR conditions expected all areas on Friday as high pressure settles over the region with diminishing winds.
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&& .MARINE...
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Short Term...WNW wind gusts up to around 30 kts will remain possible through early this evening across the outer eastern waters with seas of 3-5 ft. Winds weaken some tonight through Tuesday with gusts generally between 15-20 kts, although a few gusts up to around 25 kts will remain possible. Across the bays, wind gusts up to around 20 kts can be expected with seas of 1-3 ft. Long Term...Low pressure approaches the waters on Wednesday, with the low then strengthening in the Gulf of Maine late Wednesday night and Thursday. Westerly gales are possible behind this low Thursday afternoon and night as the low moves into the Canadian Maritimes. High pressure then builds across the waters late in the week behind the low. Low pressure develops south of the waters off the Carolina coast next weekend.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150- 152.
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&& $$ NEAR/SHORT TERM...Tubbs LONG TERM...Cannon

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