Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 042335 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 635 PM EST Sun Dec 4 2016 .SYNOPSIS... Weak high pressure across the area gives way to a weakening warm front that moves into the region on Monday morning with widespread light snow through the midday. The snow is expected to result in some travel slowdowns during the morning commute. Weather will remain active as we move through the work week with several additional systems bringing renewed chances of light rain and snow. && .NEAR TERM /THROUGH MONDAY/... As of 622 PM EST Sunday...IR imagery early this evening indicates areas of stratus holding on across much of the Adirondacks, portions of the Champlain Valley, and much of n-central into nern VT. Have made minor adjustments to increase cloud cover in spots based on latest trends. As warm front approaches, will have increasing mid-level clouds from SW to NE after midnight. Thus, just a small window of radiative cooling with light winds and partial clearing. Will generally result in lows in the low-mid 20s, but a few teens are possible if breaks materialize for a while across the nrn Adirondacks or far nern VT. Will tend to see temperatures level off after midnight as mid clouds increase. Models remain generally consistent with timing of this system with light precipitation overspreading the southwestern half of the forecast area between 4-6AM, and generally across all but far nern VT by 7AM...making for potential road impacts on the morning commute with roads becoming snowcovered and slick in spots. Warm frontal bndry is weakening as it moves across, so expecting a 3-6hr period of generally light snow, with vsby between 1-2SM in most areas. Highest snowfall amts generally 2-3" across nrn NY, with 1-2" expected across most of VT (locally near 3" for the higher summits). While these amounts are light, overall the timing could lead to a slick and slower morning commute to start the work week and as such drivers should take extra caution and time in reaching their destinations. Skies will remain cloudy through the afternoon hours, with some lingering flurries or light snow showers expected, especially across the higher terrain. Stuck with blended guidance for high temps on Monday with highs in the lower to mid 30s in the valleys and upper 20`s in higher elevations. Winds look to remain light throughout the period...initially light SE, shifting W-SW during the afternoon hours once surface low and associated warm front move east of our longitude. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 226 PM EST Sunday...The forecast challenge this period will be amount of leftover low level moisture and potential for areas of flurries/freezing drizzle monday night into tuesday...followed by slow clearing by Tuesday afternoon. Best deep layer moisture and lift associated with short wave energy and weak surface reflection will be well northeast of our region by 00z Tuesday...but soundings show plenty of low level moisture between surface and 850mb. Given the lack of any moisture in the favorable snow growth region and thermal profiles supporting temps at or below 0C...thinking areas of flurries and freezing drizzle are likely...especially mountains. Froude suggests flow is highly blocked with values <0.50...supporting low clouds and light precip back into the Champlain Valley on Monday Night. Will mention chance pops with flurries/freezing drizzle as the predominant precip type at this time. 2m temps support lows mainly in the 20s mountains to near 30f champlain and saint lawrence valleys. The question on Tuesday becomes how long the low level moisture prevails and the areal coverage of low clouds. A weak short wave ridge aloft and at the surface builds directly overhead...resulting in very light winds...with some moisture trapped below thermal inversion. Given recent trends will delay clearing until late afternoon...champlain valley and northeast kingdom...but given depth of moisture...some of the higher summits could break out by midday. Temps will be highly depend upon clouds...but will trend cooler...with highs mainly in the 30s. By Tuesday evening...clouds and precip associated with our next weak short wave energy and ribbon of mid level moisture is quickly overspreading our region. Thinking light snow arrives southwest Saint Lawrence County by 00z Weds and quickly lifts from southwest to northeast across our region by 06z Weds. Latest trends show best dynamics and moisture splitting our region to the northwest or only expecting light precip amounts. Generally a dusting to several inches in the mountains...with maybe a spot 3 or 4 inches down by Killington. Expecting little change in temps with clouds/precip with low mainly in the 20s mountains and near freezing valleys. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 226 PM EST Sunday...Any leftover precip on Weds morning will end as a period of light valley rain and mountain snow by 15z Weds. Any additional light snow accumulation will be confined above 1500 feet as bl temps warm into the mid/upper 30s by midday. A few slippery spots are possible during the weds morning commute...but overall impacts should be minimal. Still anticipating large scale mid/upper level trof to develop across the eastern conus by late week into next weekend...with temps trending toward below normal values...especially by next weekend. This transition will come with a period of unsettled weather on Thursday...with additional terrain focused snow showers for Friday into Saturday. Our coldest airmass of the season is still anticipated Saturday Night into progged 850mb temps drop between -15c and -17c. Both CMC/GFS 12z runs show a much weaker and unphased system for Thursday...with a period of snow showers expected associated with potent short wave energy and some mid level moisture. Will continue to mention likely pops with some accumulation expected over the mountains...but the lack of organized surface low pres and fast confluent flow aloft will limit significant deep layer moisture from being advected into our region. Progged 850mb and 925mb temps range between -8c and -10c on Thursday supporting highs mainly 20s mountains and 30s in the valleys...very close to normal. By Friday...favorable upslope winds of 30 to 40 knots develop with plenty of lingering 925mb to 700mb moisture leftover in mid/upper level trof axis. This moisture combined with cold air advection helping to squeeze out remaining moisture in the column will produce occasional snow showers mainly in the mountains. While not expecting heavy accumulations...several rounds of 1 to 3 inches of accumulating snow can be anticipated in the mountains given the large scale synoptic pattern. A dusting to an inch or so possible in the valleys. Progged 850mb temps drop between -13c and -15c by 18z Friday...supporting highs mainly teens mountains to upper 20s/near 30F warmer valleys. Saturday/Sunday...Similar to yesterday`s data models come back into better agreement over the weekend...with 1035mb surface ridge building directly overhead by 00z Sunday. This idea supports a general drying trend on Saturday into Sunday...with temps running about 5 degrees below normal based on 850mb temps around -16C. If skies can clear with surface high pres directly overhead with light winds...expect temps could approach near 0F at slk/colder valleys of the Northeast Kingdom by Sunday Morning. At this time will keep lows mainly in the single digits and teens...but could be colder. Lots of uncertainty develops with split flow for Sunday into early next week and associated timing of our next system. Highs only in the teens mountains and 20s valleys for both Saturday and Sunday. && .AVIATION /00Z Monday THROUGH Friday/... Through 06Z Tuesday...High pressure is over the North Country this evening with generally light winds expected overnight. Despite the high pressure area, still have lingering areas of stratus clouds, with MVFR conditions as a result at MPV/SLK, and some lingering VFR ceilings (3-4kft) at BTV/PBG. Not expecting any precipitation through 08Z. Thereafter, a warm front approaching from the south will bring developing light snow to all TAF locations. At BTV, light snow should develop around 11Z (6AM) and continue through about 17Z with 1-2" of snow accumulation expected, with minor impact to airport ground operations. Anticipate a period of IFR at all TAF locations generally 11-18Z Monday, along with HIR TRRN OBSCD. Light SE winds will shift light SW-W during the afternoon and evening hours on Monday. Overall, winds AOB 10kts are expected at all TAF locations thru the period. May see lingering MVFR ceilings even as precipitation tapers to flurries/snow showers late Monday into Monday night. 06Z Tuesday through 12Z Tuesday...BKN/OVC VFR/MVFR with scattered flurries. 12Z Tuesday through 06Z Wednesday...VFR/high pressure. 06Z Wednesday through 00Z Thursday...trending MVFR/IFR in rain/snow showers. 00Z Thursday onward...Mix of VFR/MVFR/IFR in periods of light rain/snow. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...MV NEAR TERM...Banacos/MV SHORT TERM...Taber LONG TERM...Taber AVIATION...Banacos/MV is the U.S. government's official web portal to all federal, state and local government web resources and services.