Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 170625 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 125 AM EST Sun Dec 17 2017 .SYNOPSIS... A weak upper level disturbance will move east of Vermont this evening, allowing for clearing skies as high pressure builds in from northern Ontario. It will be a cold night with diminishing winds. Low temperatures are generally expected in the single digits, and locally below zero across the northern Adirondacks. Quiet and seasonably cold weather is expected Sunday. A weak warm front will bring light snow late Sunday night into Monday. Temperatures will briefly moderate above freezing on Tuesday, before another cold front brings a return of seasonably cold conditions mid to late in the week. && .NEAR TERM /UNTIL 2 PM THIS AFTERNOON/...
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As of 117 AM EST Sunday...It`s going to be a long cold night in Saranac Lake as the latest obs continue to already be lower than our previous forecast. Its -14F and likely drops a good bit further under excellent radiational cooling this evening. Satellite imagery is now starting to show some of the low stratus over the Northeast Kingdom breaking down and so while we wont clear completely for a couple of hours expect temps to plummet once the skies do clear. Previous Discussion... In the wake of the trough, a nwly wind shift (10 mph with gusts to near 20 mph next 1-3 hrs) and a reinforcing shot of arctic air is moving in with lower dewpoints (generally in the single digits) in the St. Lawrence Valley and points upstream across Ontario. Will see clearing skies from WNW-ESE with dry air advection, and as sun sets and PBL stabilizes this eve. Will see sfc anticyclone across nrn Ontario gradually build ESEWD overnight with diminishing NW winds as well. Should set up good radiational cooling overnight, with lows mainly in the single digits above zero, except below zero readings across nrn NY with winds diminishing a bit sooner. Have gone with +7F at BTV, and -7F at SLK. Sunday will be seasonably cold but dry with sfc anticyclone cresting across nrn NY and VT. PoPs NIL with highs in the upper teens to lower 20s. Should see partly to mostly sunny conditions. For Sunday night, a subtle warm frontal feature and weak sfc reflection across Lake Huron will lift newd toward the North Country. Will see increasing clouds during the night, with a chance of light snow developing during the pre-dawn hrs across the nrn Adirondacks into wrn VT. May see a light coating of snow (D-0.5") in spots across nrn NY and Rutland County by sunrise, but limited available moisture and modest forcing for ascent should keep snowfall rates light. Temperatures will drop early in the evening, but then level off or slowly rise later with developing light S-SE winds. Lows Sunday night generally 5-15F, except near zero across far nern VT with later arrival of cloud cover.
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&& .SHORT TERM /2 PM THIS AFTERNOON THROUGH MONDAY NIGHT/... As of 249 PM EST Saturday...Light warm air advection snow showers will spread through the area Monday as a warm front moves northeastward through New England. In the upper levels, confluent zonal flow and a weakening wave moving eastward will provide some weak synoptic ascent, however moisture will be limited and total snow accumulations will remain under an inch from Sunday through Monday. As the upper- level forcing departs to the east, snow showers will generally taper off Monday afternoon into Monday evening in valley locations and any remaining snow will become more orographically focused. Daytime highs Monday will be considerably warmer than Sunday, topping out in the upper 20s to around 30 after the passage of the warm front. Monday night temperatures will dip down a few degrees, however overnight lows will be moderated by fairly extensive cloud cover. After tapering off Monday evening, coverage of snow showers will once again start to increase Monday night as the next upper- level disturbance approaches New England from the west. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 249 PM EST Saturday....As a longwave trough digs over the northeast portion of the United States, better dynamics will support more widespread precipitation Tuesday. What will start off Monday night as light snow showers will transition to rain showers Tuesday morning over lower elevations of the North Country and the Champlain Valley. By early Tuesday afternoon, most of the forecast area will have transitioned to rain as warmer air continues to pump in from the southwest. The upper- level trough axis and a surface cold front will pass through New England Tuesday night, ending the brief warm up. Colder northwesterly flow will cool the column back below freezing and any remaining rain showers will become all snow by early Wednesday morning. As the more favorable dynamics clear to the east, precipitation will become less widespread by Wednesday morning. Wednesday and Thursday will mark a return to cooler more seasonal temperatures and will be considerably drier than the start of the week, although some light snow showers can`t be ruled out as weak disturbances pass overhead. Attention then shifts to the potential for the next system to approach the area towards the end of the work week/early weekend. Models continue to spin up a surface low over the Great Lakes region Friday supported aloft by energy ejected out of a shortwave trough over the southwestern United States. This system is still well out into the future and much could change over the next week. However, confidence is increasing that next weekend could feature fairly active weather over the eastern portion of the country. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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Through 00Z Monday...Expect VFR conditions under mostly clear skies through the day. In the evening hours high and mid clouds should build in as light snow begins to move in from the south. Anticipate the snow to impact SLK/RUT first and so I`ve opted to include VCSH but generally after 06z Monday. There will be some mountain cap clouds around but they should be of little consequence to aviation takeoff or landings. Light winds are expected through the period as well. Outlook... Monday: Mainly MVFR, with periods of IFR possible. Chance SN. Monday Night: Mainly MVFR, with local VFR possible. Chance SHSN, Slight chance SN. Tuesday: Mainly MVFR, with local VFR possible. Likely SHRA, Chance SHSN. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHSN, Chance SHRA. Wednesday: Mainly VFR, with areas MVFR possible. Chance SHSN. Wednesday Night: Mainly MVFR, with areas VFR possible. NO SIG WX. Thursday: Mainly VFR, with areas MVFR possible. Slight chance SHSN.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/Deal/Lahiff SHORT TERM...RSD LONG TERM...RSD AVIATION...Deal

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