Area Forecast Discussion
Issued by NWS Portland, ME

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793 FXUS61 KGYX 170339 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1039 PM EST Thu Nov 16 2017 .SYNOPSIS... Developing low pressure will track through the Gulf of Maine this evening. Coastal rain and some accumulating interior snows are expected. Gusty northwest winds follow this system late tonight and Friday. High pressure builds in again for Friday before the next storm system arrives late Saturday and Sunday with another mixed bag of precipitation. High pressure then returns for early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Update... Have updated the forecast based on current surface observations. Stratiform precipitation will continue to shift east, with the remaining precipitation switching to more of an upslope snow shower condition overnight. Radar imagery continues to show an area of steady precip exiting to the east Rockland, however some backbuilding has been noted at times as the system begins to intensify. Mesoscale models suggest this should be out of our region by around or shortly after midnight. Expect some accumulating snows in the mountains, mainly above 1500 feet. Areas of fog continue to develop this evening. The moisture will lift after midnight as winds become west and drier air enter the region behind the departing and intensifying area of low pressure. Breezy, but drier conditions expected thereafter. Prev Disc... At 19z...a 1000 millibar low was vicinity of the Ottawa Valley with a trailing frontal system through the mid Atlantic region. A 1006 millibar low was rapidly developing near long Island with vicinity of Cape Cod with isallobaric analysis indicating three hour pressure falls approaching 5 millibars of Cape Cod. Warmer air has overspread much of the forecast area in advance of the system...with any residual snow generally limited to the higher terrain at moment. For tonight...the secondary low will become dominant by evening with rain...heavy at times changing to wet snow across the higher terrain and some interior sections before ending. It appears to be a case of too little too late for the column to cool and wipe out the warm air near the surface before the precipitation ends in many areas. However...developing upslope flow and leftover moisture should generate several inches of fresh snow across the mountains and foothills through dawn. Northwest winds will develop and increase to 15 to 25 mph as the coastal low races into downeast Maine late tonight.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... On Friday...some lingering upslope clouds and morning snow showers to start the day across the higher terrain where some additional light accumulations remain possible. Elsewhere...a mainly sunny and windy day. It`ll be a very windy day at that with Northwest winds of 15 to 25 mph gusting between 30 and 40 mph at times. Clear and cold with diminishing winds Friday night as high pressure builds across the region. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Saturday begins with a low pressure system moving through the Great Lakes region toward us. Expect to see a weak warm front lift across the forecast area late Saturday afternoon. Southwest flow ahead of this system will allow temperatures on Saturday to climb into the 40s at most locations. As the system moves through Saturday night, temperatures will continue to increase right through morning. Most locations should see rain with this system, although mountain areas may start out as snow and then transition to rain as the warm air moves in. If there is any snow cover in the mountains, then there will likely be some pretty thick fog that sets up overnight on Saturday as warm air moves across the cold snow. Temperatures will top out by midday on Sunday, with upper 30s in the mountains and upper 40s to lower 50s along the coast. Once the cold front comes through and cold air advection gets going in earnest, we should see temperatures plummet during the afternoon and evening hours. Winds will also shift to the northwest and increase. Expect to see wind gusts to about 35mph Sunday evening. The cold air bottoms out on Monday and temperatures only recover into the 30s. Sunny skies and return flow will help temperatures moderate on Tuesday and Wednesday into the 40s. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... Short Term /through Friday Night/...Conditions improving to MVFR across the mtns tonight in lingering snow showers and to VFR elsewhere overnight. NW winds will develop behind a departing coastal low and gust up to 35 kt late tonight and during the day Friday before subsiding Friday evening. VFR with light winds expected Friday night. Long Term... Expect to see at least some LIFR/IFR fog Saturday night, especially at TAF sites like KHIE, where there could be some remaining snow cover. Should see some IFR/MVFR cigs and vsbys both Saturday and early Sunday in rain and low clouds. Once the front passes through the region early Sunday, winds will shift to the northwest and become gusty. LLWS may be an issue late Sunday and Sunday evening. VFR conditions should return for Monday through Wednesday. && .MARINE... Short Term /Through Friday night/...Gale warnings continue for late tonight and Friday as wind gusts of 35 - 40 kt are expected. Long Term... Cold frontal passage early Sunday will bring gusty winds to the region Sunday afternoon and evening. Winds will almost assuredly be strong enough to warrant an SCA, and will likely be close to Gale criteria. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Gale Warning from 4 AM to 8 PM EST Friday for ANZ150>154. && $$ JC is the U.S. government's official web portal to all federal, state and local government web resources and services.