Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 160219 AFDGYX Area Forecast Discussion National Weather Service Gray ME 919 PM EST Sun Jan 15 2017 .SYNOPSIS... High pressure builds in tonight and Monday, then shifts east on Tuesday. Low pressure crosses the region Tuesday night into Wednesday night and will bring a mix of snow and rain to the area. High pressure builds in at the end of the week, with above normal temperatures. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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915 PM Update: High clouds will continue to spill through the upper ridge over the area for the rest of tonight. Otherwise very quiet night as winds have gone calm and temps continue to fall but are staying in the forecast range. No need for any changes at this time. 655 PM Update: Satellite Imagery shows some high clouds spilling across the mountains and into central and southern areas of ME/NH at this time. This will be the trend the rest of the night ad well reflected in cloud grid forecast. Input latest obs data and all trends on track and only very minor tweaks needed. A very quiet night. Previous Discussion: Mainly clear skies over southern areas tonight, with, once again, more cloudiness in the north and mountains. A couple of weak, but fast moving short waves will allow for some Cirrus over northern areas. Also, some upslope cu may become trapped under the inversion tonight in the higher terrain. This will once again allow for a wide range of overnight mins that will be very dependent on the cloud cover. Some areas will radiate under clear skies and light winds.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... High pressure will crest over the region early Monday before heading out to sea. A weak weather disturbance well north of Maine will allow for a wind shift over northern areas later in the day. However this system is very moisture starved, with little impact in our region. High pressure over Eastern Canada will reassert itself Monday night, setting up cold, dry air in northern New England as a system approaches from the Midwest. Some high thin cloudiness will be approaching the region Monday night, setting the stage for precipitation entering for the long term portion of the forecast. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Over the past day...models have come into better agreement on the longwave pattern through the upcoming weekend. We begin with a low amplitude split flow regime that transitions to a high amplitude regime featuring a deep trough over the western CONUS with a downstream ridge here in the eastern CONUS. While longwave pattern is in better agreement...we continue to see differences in shortwave strength and timing...particularly early in the forecast period. Overall...the northern stream will keep arctic air bottled up to our north and we`ll see temperatures average above normal for the period. In the dailies...a ridge of high pressure will retreat offshore on Tuesday. A shortwave impulse and associated surface low approach from the Great Lakes for Tuesday night and Wednesday with a secondary low advertised to develop late Wednesday over southeast coastal New England. With models now putting more emphasis on the secondary low...we`re trending colder both surface and aloft increasing the likelihood of more white then wet or freezing...especially across the mountains and foothills. For Wednesday night into Thursday...proximity of the upper trough and a surface trough extending northwest into the region from the offshore low support lingering snow or snow showers and at least some light additional accumulations. A ridge of high pressure should then slide east across the region for Friday and much of the upcoming weekend. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Short Term...VFR conditions through Monday night with some high, thin cirrus in the mountains as well as upslope Cu. Long Term... Tue night - Wed...IFR in SN/PL/RA with areas of LIFR. Thu...areas of MVFR in shsn. && .MARINE... Short Term...Winds continue to gradually diminish. Will be lowering the SCAs with this package. Long Term... Wed - Thu...Small craft conditions are likely...With gale force possible gusts outside the bays. Fri...Small Craft conditions are possible. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.