Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 030451 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1151 PM EST Fri Dec 2 2016 .SYNOPSIS... An upper trough will move southeast from Canada overnight, and will bring a chance of rain and snow showers. The region will remain under cyclonic on Saturday with a chance for more rain and snow showers. A ridge of high pressure will build into the north country on Sunday, and will bring fair and dry weather to the north country from Sunday through Tuesday. && .NEAR TERM /UNTIL 6 PM SATURDAY EVENING/... As of 1100 PM EST Friday...Best 850-700mb forcing for ascent with mobile shortwave trough has passed south of our region as of 03Z. Anticipate some continued light snow shower activity, mainly confined to orographically favored areas. Lapse rates are initially quite steep with Froude #s greater than 1, placing the majority of ongoing snow shower activity over and immediately downstream of the Green Mtns. The KCXX reflectivity at 0330Z shows majority of returns across the spine of the Greens, with some light snow being reported also by ASOS at MVL and MPV...so the idea of unblocked flow and associated pcpn patterns is consistent with current observations. Anticipate a modest temperature inversion forming toward daybreak, per 00z NAM model soundings, and this may yield some better chances for orographic blocking and some occasional snow showers in the BTV area toward 12Z. Again, not expecting any major impacts, but could see a slick spot or two for the higher elevation roads, including I-89 from Richmond east to Brookfield. Remainder of the forecast is on track. Previous Discussion...An upper trough will move southeast from Canada overnight, and will bring a chance of rain and snow showers to the North Country through the remainder of this evening and overnight. Modest low-level cold advection associated with this trough will allow snow levels to gradually fall, from near 1000ft at 00Z, to the valley floors after 06Z. With WNWLY flow bringing some orographic enhancement, the higher elevations of the northern Adirondacks and Green Mountains should see 2-3" of snowfall overnight, with a slushy coating to 1" possible at the lower elevations. Overnight lows temperatures will range from 33-35F in the Champlain Valley, to 27-32F elsewhere. On Saturday, the North Country will remain under cyclonic flow from the departing surface low pressure area over the Canadian maritimes. Will go with chance PoPs for rain and snow showers on Saturday. Highs on Saturday will be mainly in the 30s. && .SHORT TERM /6 PM SATURDAY EVENING THROUGH SUNDAY/... As of 349 PM EST Friday...Northwest flow persists with cloudy skies and snow showers, mainly across elevated terrain and western slopes. Froude number forecasts increasingly blocked flow throughout the night, but deeper moisture will be decreasing throughout the night. Therefore, high chance POPs focused around the terrain and immediate western slopes will decrease throughout the night with windward valleys possibly seeing a few snow showers. There is a chance for DZ/FZDZ as indicated by NAM BUFKIT thermal profiles as moisture layer shrink from above resulting in lack of ice nuclei. GFS BUFKIT brings this drier air aloft into the area later with moisture also eroding from the surface, more in line with stubborn low clouds than precipitation. At this point in time, confidence not high enough to include DZ/FZDZ in forecast. Min temperatures will generally range from the upper teens to mid 20s. Weakening northwest flow with drying trend will bring an end to snow showers mid-late Sunday morning as high pressure builds in from the Great Lakes region. Expect partial clearing of clouds under the ridge, but lingering low level moisture trap under an inversion may keep portions of the North Country in mostly cloudy skies. Max temperatures will range from the upper 20s to upper 30s. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... As of 349 PM EST Friday...Models consistent with regard to dry Sunday night and only low chances of light precipitation, mainly across our western counties Monday as a dampening shortwave trough moves across the region. Increasing clouds and scattered light snow, with rain mixing in the valleys will be accompanied by max temperatures in the 30s. High pressure returns with dry weather, partial sunshine and light winds Monday night through Tuesday. Temperatures will be near normal to slightly below normal for early December. A mid-week storm is poised to affect the North Country, however models still differ on the evolution of southern stream 500mb shortwave moving across the SE USA and reflected at the surface as a coastal low by late Tuesday. Ridging over New England will affect how far north the 500mb shortwave travels along with progression of larger 500mb low over south central Canada. Potential for mixed precip event as the surface high slides north Tuesday night keeping NE cold air advection near the surface while warming aloft occurs as precip moves in. Still much uncertainty. && .AVIATION /06Z Saturday THROUGH Wednesday/... Through 06Z Sunday...An upper trough is moving through the region. Scattered snow showers mainly in the higher elevations are occurring with a chance of some activity at the stations in the valleys as well. Expect VFR ceilings to trend down to MVFR overnight, with some local pockets of IFR mainly at KSLK/KMPV. Through the day Saturday, ceilings will linger at low VFR/MVFR before gradual improvement back to VFR overall after 21Z. Surface winds from the northwest overnight and into the daytime hours at 10-15 knots with gusts up 20 knots expected. Outlook 06Z Sunday through Wednesday... 06Z Sunday through 12Z Sunday...Mix of VFR/MVFR with local IFR possible at KSLK in scattered rain/snow showers. 12Z Sunday through 06Z Wednesday...Mainly VFR with high pressure building in. Periods of MVFR ceilings possible, especially at KMPV/KSLK. 06Z Wednesday through 00Z Thursday...areas of MVFR/IFR in rain and snow showers. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...WGH NEAR TERM...Banacos/WGH SHORT TERM...KGM LONG TERM...KGM AVIATION...MV

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