Area Forecast Discussion
Issued by NWS Burlington, VT

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355 FXUS61 KBTV 172016 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 316 PM EST Tue Jan 17 2017 .SYNOPSIS... Low pressure will move northeast through the eastern Great Lakes today and up the St. Lawrence Valley tonight and Wednesday. A mix of wintry precipitation will begin in northern New York late this afternoon, and spread east across Vermont tonight, and continue area-wide through Wednesday. Be ready for slow travel conditions tonight and for the morning commute on Wednesday. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... As of 107 PM EST Tuesday...The only change to the forecast was to raise max temperatures for today up a degree or two, as temperatures in some locations already warmer than forecast. Previous discussion from 621 AM EST Tuesday...No changes to this first part of the forecast, so far tracking along well. Temperatures in the teens and lower 20s, with clear skies. KMSS reporting 6sm br but otherwise no other obstructions to visibility. A quiet first half of the day as the surface ridge shifts east ahead of our next approaching storm system. Light east to southeast low level flow ahead of the low, with increasing clouds already seen approaching on IR satellite. High temps today in the low to mid 30s. 500 mb shortwave trough will move out of the great lakes toward 00z and track west to east across the forecast area between 00-12z Wednesday. Southerly flow ahead of the shortwave will spread warm frontal precipitation across the region beginning after 18z in northern NY and into VT after about 22z, and continue overnight into Wednesday. Diurnal cooling will be offset by warm air advection tonight with a mix of precip types. Western portion of New York zones the most susceptible to the biggest mix, where warm air intruding up the St. Lawrence valley will allow for freezing rain to mix with sleet and snow. In Vermont, below freezing temps through the low levels will keep precip type more toward all snow although there will be a brief period at the onset of the event with sleet mixed with the snow for most all Vermont except the Northeast Kingdom. With east to southeast flow below 850 mb expect to see greater snowfall accumulations on the eastern slopes of the Green Mountains and to a lesser extent on the northeast slopes of the Adirondacks. Up to a half inch of precip forecast, equating to 3 to 6 inches of snow in east central VT and eastern Essex County NY. Lesser snowfall amounts toward St. Lawrence Valley where sleet/freezing rain mix lower snow ratios. Snow accumulations out there to be generally 1-2 inches, with up to a tenth inch of ice, mainly in southern St. Lawrence county. Southeast downslope flow in the northern Champlain Valley, especially northwest Vermont. This will keep NW Vermont out of the advisory with 2-4 inch snow totals. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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As of 316 PM EST Tuesday...Generally improving conditions as 500mb shortwave exits east and ridge begins to build in over the North Country. Lingering light showers focused over the high terrain will diminish Thursday and Thursday night. Cooler air will accompany high pressure with 925mb temperatures remaining in the negative single digits to single digits above 0C. As the 500mb ridge crests over the region, gradually clearing skies will result in min temperatures in the 20s to low 30s throughout the period. Max temperatures will generally range from the mid 30s to low 40s Thursday and Friday.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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As of 316 PM EST Tuesday...A shortwave will attempt to move into the 500mb ridge and produce a slight chance for precipitation but reinforcing ridge at the surface and limited moisture will likely lead to some clouds but not much precip Saturday into Saturday night. More significant system will develop a closed surface low Sunday night around the Ohio River Valley with large southern stream 500mb low. Moisture feeding from Carolina coast will bring PWATs around 1 inch into the North Country as negatively tilted 500mb trough moves NEwd. This will result in warm air aloft and possible mixed precip moving into the North Country from south to north late Monday. Models differ on track of primary surface low, affecting how much warm air moves into the region. But GFS and ECMWF agree on strong low level jet of 50-65kts late Monday through Tuesday.
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&& .AVIATION /20Z Tuesday THROUGH Sunday/... Through 18Z Wednesday...ceilings will continue to lower through 00Z Wednesday. Expecting precipitation to begin at the TAF sites between 22Z Tuesday-01Z Wednesday. Bufkit forecast soundings suggesting mainly snow across the Vermont, with some sleet mixed in at times across southern Vermont. Expecting a mix of snow, sleet, and a period early this evening of freezing rain across northern New York. Ceilings will lower to IFR across the region by 02Z Wednesday. 18Z Wednesday - 00Z Thursday...MVFR/IFR in periods of light snow. 00Z Thursday through 00Z Friday...VFR with brief MVFR/IFR rain/snow showers. 00Z Friday through 00Z Monday...VFR, as a ridge of high pressure will be over the region. && .BTV WATCHES/WARNINGS/ADVISORIES...
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VT...Winter Weather Advisory until 1 PM EST Wednesday for VTZ006>012-017>019. NY...Winter Weather Advisory until 7 AM EST Wednesday for NYZ029- 087. Winter Weather Advisory until 1 PM EST Wednesday for NYZ028- 030-031-034-035.
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&& $$ SYNOPSIS...Hanson NEAR TERM...WGH/Hanson SHORT TERM...KGM LONG TERM...KGM AVIATION...WGH

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