Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 290323 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1023 PM EST Mon Nov 28 2016 .SYNOPSIS... High pressure over the region moves east tonight. A warm front will cross the region Tuesday and Tuesday night bringing some mixed wintry precipitation that will change to rain. This will be quickly followed by another low tracking out of the mid Atlantic region into New England Wednesday and Thursday, bringing rain which changes to snow in the north. Another weak low passes north of the area on Friday, with high pressure building in by the weekend. && .NEAR TERM /THROUGH TUESDAY/...
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0322Z Update...Will be expanding the freezing rain advisories to far southwest NH based on current trends and forecast of ice accretion. Temperatures continue to radiate into the 25 to 30 degree range which increases confidence for freezing rain into that region tomorrow. This matches up well with ongoing WFO BOX forecast and advisories further to the south. Adivsories may need to be expanded further to the east if current trend continues. The rest of the forecast will remain relatively unchanged with continuing the trend of lowering the mins overnight. Prev Update... Have updated the grids based on current conditions and latest suite of mesoscale models. Clear skies, light winds and low dew points remain over the region. Radiational cooling has begun. The big question of the evening is how low will the temperatures go prior to the cirrus shield dominating the low level readings. Have lowered mins based on current temperatures, but expect the temperatures the begin to level off by around midnight. Made minor adjustments to cloud and dew point forecast in the grids, otherwise, little change to the package. Low level temperatures may allow for changeable ptypes during tomorrows forecast. Prev Disc... High pressure over the area tonight will initially allow clear skies and calm winds allowing radiational cooling to occur. Clouds will quickly spread over southern and central areas after midnight putting a stop to further cooling so overnight lows should occur shortly after midnight before slowly climbing toward morning due to lowering clouds and a developing warm air advection pattern. Precipitation arrives toward morning over southern NH but temperatures may already be above freezing due to slowly rising temps with the warm air arriving in the boundary layer and aloft so for now opted not to issue any advisory. Further north into central NH and southwest interior ME enough cold air will be in place to allow mixed precip of several types to occur with even some light snow accumulations in a few areas. Due to several PTYPES opted to go with a winter weather advisory for those areas during the onset.
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&& .SHORT TERM /TUESDAY NIGHT/... A complicated wintry mix forecast for Tuesday into Tuesday night. The winter weather advisories get expanded across the mountains and foothills Tuesday due to enough cold air in place combined with fairly high amounts of qpf that expand north and east. Used the RFCQPF forecast which ranges from .40-.80 totals. In the mountains generally 3-6 inches of snow expected while in the inland valleys a mix of frzg rain/sleet and snow changing to all rain occurs in the afternoon with little or no snow accumulations expected. The strong warm low/mid level east to southeast flow eventually scours out all the cold air in the afternoon allowing all but the mountain areas of Maine to change to rain. Not much cold air damming will exist with this system. By evening some areas in the mountains may still have a mix before ending. Elsewhere as the short wave and its associated surface low quickly exit, the rain will taper to scattered showers before ending. Temperature forecast will be critical on PTYPE. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The models are in decent agreement on the longwave pattern through the start of the upcoming weekend. Thereafter...model solutions diverge considerably adding significant uncertainty in sensible weather details by the second half of the weekend into early next week. Temperatures through at least Saturday will average above normal as mean jet streamposition keeps the really cold air bottled up to our north and west. We begin the period in between disturbances with an upper trough extending from the Great Lakes southward through the central CONUS. However...clouds and precipitation will quickly stream northward in advance of shortwave impulse with thickening clouds and precipitation spreading into New Hampshire and Western Maine by dusk. Forecast soundings suggest rain with the exception of areas near the international border in Maine where it may begin as a wintry mix. For Wednesday night and Thursday...occluding frontal system pushes into New England with models agreeing on triple point low developing over Maine coastal waters on Thursday. This surface development will draw colder air into the higher terrain which will help precipitation end as snow there on Thursday. Behind this departing disturbance...a broad trough with a series of embedded shortwaves that will traverse the forecast area through Saturday. This will result in considerable clouds for the higher terrain with upslope snow showers. Elsewhere...varying amounts of clouds with passing shortwave impulses as well as a low pop for rain/snow showers boundary layer temperature dependent. By Sunday...a model blend offers weak ridging and a brief respite before the next disturbance approaches the region for the start of the new work week. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Short Term...VFR conditions through tonight. MVFR/IFR conditions will spread south to north early Tuesday with mixed precipitation. By Tuesday afternoon the mixed precipitation will have changed to rain over all areas except in the western mountains of Maine. Conditions will slowly improve Tuesday night. Weather observations for Rockland are note available and the FAA is working to resolve the issue. Until these become available again, the Rockland TAF will be issued based on best estimate conditions with no amendments scheduled. Long Term... Wed PM...MVFR wth lcl ifr in ra and sn. Thu...Widespread IFR in RA and mtn ra/SN. Fri - SAT...Areas of MVFR in mtn shsn && .MARINE... Short Term...High pressure centered over the waters tonight will allow a period of calm winds and low seas. Low pressure will move across the Gulf of Maine Tuesday into Tuesday night and will allow southeast winds to increase and build seas to SCA levels. Over the western outer waters Gale warnings have been issued for a period of even stronger winds Tuesday evening. Long Term... Thu...SCA`s possible...with Gale force gusts outside the bays. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Weather Advisory from 5 AM to 10 AM EST Tuesday for MEZ018-019. Winter Weather Advisory from 8 AM to 4 PM EST Tuesday for MEZ012-013. Winter Weather Advisory from 10 AM to 10 PM EST Tuesday for MEZ007>009. NH...Winter Weather Advisory from 5 AM to 10 AM EST Tuesday for NHZ003-005-006-008>010. Freezing Rain Advisory from 5 AM to 10 AM EST Tuesday for NHZ007-011-015. Winter Weather Advisory from 8 AM to 4 PM EST Tuesday for NHZ001-002-004. MARINE...Small Craft Advisory from 1 PM Tuesday to 4 AM EST Wednesday for ANZ150-151-153. Gale Warning from 1 PM Tuesday to 1 AM EST Wednesday for ANZ152-154.
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&& $$ Cannon

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