Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 110855 AFDGYX Area Forecast Discussion National Weather Service Gray ME 355 AM EST Sun Dec 11 2016 .SYNOPSIS...
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High pressure will slide offshore south of New England today. Low pressure will approach from the west tonight and will move through New England on Monday. Low pressure will continue east into the maritimes Monday night. An arctic front will approach from the west on Tuesday and will move through the region Tuesday night. A second arctic front will approach from the west on Wednesday and will push through the region Wednesday night. A trough of low pressure will push in from the west on Thursday and will cross the region Thursday night. High pressure will build in from the west on Friday.
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&& .NEAR TERM /THROUGH TODAY/...
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The coldest morning of the young winter season is upon us with 3 am temperatures across the area anywhere between 5 below and 15 above zero. High pressure will remain over the area today with partly sunny skies and light winds. Clouds will increase from west to east today as the next low pressure system approaches from the west.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
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Overall, not too much has changed from the previous forecast. A quick-moving short wave trough will approach from the west tonight as surface low pressure develops well to our south and moves into the Gulf of Maine on Monday. Snow is expected to begin overspreading the region this evening...first across southwestern NH and then northeastward from there. Most locations are expected to be snowing by the midnight to 2 am time frame. There is still considerable uncertainty in storm total snow amounts due to the uncertainty in low level thermal profiles. Much of the mesoscale guidance suite brings low level warm air into the coastal plain pretty quickly late tonight and Monday morning. This is a bit unusual for hi-res guidance given the very cold air mass in place. However, it cannot be completely ignored given the strong southeasterly low level jet that develops over sea surface temperatures that are anywhere from 1 to 3 degrees above normal for this time of year. However, we went colder than this guidance based on coastal front climo with a cold air mass such as this in place. The forecast temperatures/QPF/snowfall through monday were based on a blend of available guidance but most closely resembles the 00z ECMWF run which seemed to be a good compromise. The upshot is that snow is expected to overspread the region from SW to NE tonight, and possibly be heavy at times late tonight and early Monday morning. The snow then mixes with or changes to sleet and rain on the coast and perhaps southern NH Monday morning. We think most areas will see advisory criteria snowfall by the time this change takes place. Winter weather advisories have been issued where the highest confidence exists in getting 3 to 5 inches of snow but less than 6. For those areas where around 6 inches of snow is expected, winter storm watches remain in place. This is where highest confidence exists in 6 or more inches of snow falling (coastal front enhancement, good dendritic snow growth profiles, best forcing for ascent), but confidence remains too low to issue a warning at this time. A decision to go warning or advisory will be made during the day today. Either way, the Monday morning commute will be a slippery one in all areas. Due to the fast moving nature of the system, the snow or mixed precip will end from west to east during the afternoon with some sun possible by the time the evening commute comes around.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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Low pressure will head into the maritimes Monday night as a narrow ridge of high pressure builds in from the west. Expect clouds and flurries in the mountains through the first half of the night with partial clearing after midnight. Downwind of the mountains variable evening clouds will clear as downslope winds kick in. Should see lows slightly above normal for a change with mid teens to lower 20s north and lower to mid 20s south. First in a series of arctic fronts will approach from the west on Tuesday. After a mostly sunny morning expect increasing clouds during the afternoon...mainly in northern and western zones. May be a few snow showers or squalls in the mountains. Highs will range from the mid 20s north to the mid 30s south. Cold front will push east of the forecast area Tuesday night. Looking for variable clouds in the north and partly cloudy skies elsewhere. Lows will range through the teens north and lower to mid 20s south. The true surge of arctic air will head toward the region on Wednesday. Will once again see a mostly sunny morning with clouds increasing in the afternoon along with occasional snow showers. Highs will range through the 20s north and upper 20s to mid 30s south. Arctic front will sweep through the region Wednesday night accompanied by snow showers and squalls. Will likely see several inches of accumulation in the mountains and a light dusting to an inch in local squalls downwind of the mountains. Lows will bottom out in the single numbers north and will range through the teens south. Thursday looking blustery and very cold with scattered snow showers as several spokes of energy rotate around deep upper low. Highs will range through the teens north and lower to mid 20s south. Shortwave rotating around upper low will swing through the region Thursday night keeping snow showers and some squalls in the forecast along with some light accumulations. Expect northwest gradient to tighten considerably behind surface trough by Friday morning. Lows overnight will range from zero to 10 below north and in the single numbers south. Very windy and cold on Friday as surface high pressure builds in from the west. Highs will range from 5 to 15 north and mid teens to lower 20s south. More cold for Friday night as high pressure crests over the region. Expect lows of 5 below to near zero north and in the single numbers south. High pressure will shift offshore on Saturday as a broad area of over-running forecast to shift in from the west ahead of intense low pressure moving north through the Great lakes. At this point looks like snow Saturday going over to mixed precip Saturday night.
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&& .AVIATION /08Z SUNDAY THROUGH THURSDAY/...
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Short Term...VFR today. Conditions deteriorate to IFR tonight in snow and mixed precip and continue through Monday morning. Improvement is foreseen later Monday afternoon. Long Term...VFR Monday night with areas of MVFR ceilings/vsby in the Mountains. VFR Tuesday Through Wednesday. Areas of MVFR ceilings/vsby on Thursday.
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&& .MARINE...
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Short Term...A gale watch has been posted for the ocean waters for late tonight and Monday as low pressure moves across the Gulf of Maine. Long Term...SCA`s may be needed Monday night and Thursday.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Storm Watch from late tonight through Monday evening for MEZ012>014-018>022. Winter Weather Advisory from midnight tonight to 7 PM EST Monday for MEZ007>009-023>028. NH...Winter Weather Advisory from 9 PM this evening to 7 PM EST Monday for NHZ001>003-005-012>014. Winter Storm Watch from late tonight through Monday evening for NHZ004-006-008>010. Winter Storm Watch from this evening through Monday evening for NHZ007-011-015. MARINE...Gale Watch from late tonight through Monday evening for ANZ150- 152-154.
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&& $$ NEAR/SHORT TERM...MLE

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