834 FXUS61 KBTV 280103 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 803 PM EST Mon Jan 27 2020 .SYNOPSIS... Upper low will slowly depart across the Canadian Maritimes tonight, but will still maintain low overcast conditions and scattered snow showers overnight. An additional coating to 2 inches of snow will be possible through early Tuesday morning, and a few icy spots are expected as temperatures fall into the 20s. Thereafter, high pressure will build eastward from northern Ontario, bringing drier weather and more seasonable temperatures through the end of the work week. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 803 PM EST Monday...Quick update to introduce patchy/areas of -dz/-fzdz mixed in w/occnl light snows into the overnight hours per recent report from eastern Chittenden County and Pierre-Trudeau Intl in Montreal also reporting very light -fzra. Model sounding profiles are quite mixed, showing the dendritic snow growth zone going in and out of a saturated vs. unsaturated state overnight depending on the solution, though most recent HRRR output seems to be leaning toward the latter. Light snow accumulation forecasts were not changed with this update owing to uncertainty in future coverage of any -dz/-fzdz. The rest of the forecast in regard to cloud cover, winds, temperatures etc. also remain unchanged at this point. Prior discussion... A moist cyclonic flow prevails across the North Country on the swrn periphery of departing deep-layer low over the Gulf of St. Lawrence. A low overcast and periods of light showers will continue this afternoon through tonight, and 18Z radar trends indicate an increase in radar reflectivity across nwrn VT nwd into srn Quebec. PBL temperatures are marginal for snow in the valley locations, thus continued with the idea of a light rain/snow mix at times in the St. Lawrence and Champlain Valleys. As we get past sunset, low-level thermal profiles cool sufficiently that we should see just snow showers across the region, and a better chance at some accumulating snow at the lower elevations. It does appear based on 12Z BTV-4kmWRF that orographically blocked flow will become an increasing factor overnight, with Froude Numbers falling below 0.5 along the western slopes of the Green Mtns after 02Z. This is also reflected in the NAM-12 forecast sounding at BTV, with a slight increase in hourly snowfall rates late this evening through about 12Z Tuesday. Have increased PoPs upwind of the Green Mtns on the VT side of the Champlain Valley as a result as we head through the evening hours. Still a minor event overall, with total snowfall accumulations through 12Z Tuesday of a dusting to 2" in most locations, including 1-2" around BTV and points east. May see 2-4" across the higher summits of the nrn Adirondacks and central/nrn Green Mtns. Also, as temperatures fall into the upper 20s tonight, will see some developing icy spots, so drivers should exercise caution tonight and into the morning commute time frame on Tuesday. On Tuesday, snow showers will taper off to mountain flurries and a few breaks are expected to develop in the overcast with loss of cyclonic flow aloft and diminishing mid-level moisture. NW winds of 5-10 mph expected overnight into Tuesday bring modest low-level CAA, and temperatures several degrees colder for Tuesday. Highs are expected in the upper 20s to lower 30s. Surface high pressure builds ewd across northern Ontario on Tuesday night. Should result in a quiet night across the North Country. Lows mainly in the teens, but single digits above zero are expected across the northern Adirondacks and far nern VT. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 245 PM EST Monday...A 1030 mb surface high will sink south across the North Country on Wednesday which will cut off any lingering light snow showers along the higher terrain. Although this high pressure has origins over northern Hudson Bay in Canada, the cold air remains locked up in the arctic which will keep afternoon high temperatures on Wednesday right around normal with readings in the lower to upper 20s. Wednesday night, however, looks on the chilly side as the surface and boundary layer will decouple shortly after sunset which will allow winds to become light and variable while skies continue to clear. Overnight lows in the single digits above and below zero are expected, with the coldest temperatures expected across the Adirondacks and Northeast Kingdom. Some of the hi-res guidance shows 10-15 knots of due northerly flow right off the deck Wednesday night which could create some lake induced clouds across parts of the Champlain Valley given the lack of ice coverage on Lake Champlain. This could cause temperatures in a few locations to remain in the teens overnight with the possibility of a few flurries but otherwise should have little impact on the forecast. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 245 PM EST Monday...High pressure will remain entrenched across the North Country on Thursday and Friday with mostly sunny skies expected across the region. The air mass underneath the high pressure system will continue to moderate with high temperatures on Thursday in the lower to upper 20s and in the mid 20s to mid 30s on Friday. Overnight lows will be a bit warmer Thursday night with lows in the single digits above zero and in the teens Friday night. The next chance for any type of measurable precipitation won't occur until Saturday afternoon as a complicated system approaches the region as high pressure departs to the northeast. There will be two separate waves of energy with the first forming over the Gulf of Mexico and the second developing over the Mid-West. The Gulf of Mexico system will likely be the stronger of the two systems but it looks like it's going to pass well to our south and east into the Atlantic. There is some uncertainty amongst some of the ensemble members but the majority show this system pushing east of benchmark which would follow the pattern so far this winter with both positive NAO and AO currently being observed. This would likely keep us as spectators as all precipitation would likely be east of Vermont. The second wave will move across the Mid-West Saturday morning and track into New England Saturday night/Sunday morning. This wave will be enhanced by a closed 500 mb low that will help bring the return of some snow showers. Moisture will be extremely limited with the first system over the Atlantic shunting the majority of the moisture offshore. Nevertheless, it looks like 1-4 inches of snow will be possible with the highest amounts along the western slopes of the Adirondack and Green Mountains. The upper level trough will swing through Monday with upper level ridging building in Monday night into Tuesday. High temperatures will continue to moderate over the weekend with temperatures on Sunday warming into the lower to mid 30s across all of the North Country. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... Through 00Z Wedesday...Mainly OVC skies expected over the next 24 hours under light north/northwesterly flow in the 3-7 kt range. Cigs to range mainly MVFR to VFR, though some occnl IFR in light snows/snow showers likely to occur here and there through the evening/overnight hours, mainly at KBTV and KSLK. After 18Z Tuesday a gradual trend toward VFR at valley sites of KMSS/KPBG/KBTV expected. Outlook... Tuesday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...JMG/Banacos SHORT TERM...Clay LONG TERM...Clay AVIATION...JMG