Area Forecast Discussion
Issued by NWS Burlington, VT

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652 FXUS61 KBTV 021433 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 933 AM EST Fri Dec 2 2016 .SYNOPSIS... Deep low pressure moving slowly east through southern Quebec will continue to influence the North Country`s weather through Saturday, with abundant clouds and periods of higher terrain rain and snow showers. Some sunshine is in the forecast for the later half of the weekend as a ridge of high pressure builds into the region on Sunday, with fair and dry weather continuing into the early part of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 933 AM EST Friday...Composite radar loop showing some scattered rain and snow showers over portions of northern New York and northwest Vermont at this time. Previous forecast of rain and snow showers for today still looks good, so no changes have been made to the current forecast. Previous discussion from 634 AM EST Friday...Very little change from the previous forecast thinking for the next 24 hours as deep low pressure currently over southeast Quebec very slowly drifts eastward to the Canadian maritimes by early Saturday morning. Saw a little bit of a break in shower activity earlier this morning as deeper moisture associated with the occlusion that passed through yesterday shifted north and east of the area, with very very slight mid-level ridging occurring in its wake. But now as we move through the mid-morning hours, additional shortwave energy currently shifting into the eastern Great Lakes will round the base of the upper trough and redevelop rain and snow showers again as more favorable west/northwest flow develops, focusing precipitation along the higher terrain of the western slopes of the Adirondacks and northern Green Mountains. As this energy drops further into the region early this evening, we`re likely to see some activity light up in the northern Champlain Valley before the flow turns fully to the northwest and precipitation once again becomes more orographic in nature through the remainder of the night. Freezing levels begin the period this morning generally around mid- slope at 2500 feet, then gradually lower to around 1500 feet by 00z, and further almost right to the valley floor around 500 ft overnight. In general this supports snow as the dominant ptype across the higher summits, while lower elevations will be mainly rain during the day today, and a rain/snow mix tonight. The resulting snow accumulations will be only a dusting to perhaps an inch below 1500 feet, but upwards of 4-6" can be expected above 2500 feet. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... As of 300 AM EST Friday...Then more of the same for Saturday as we remain in northwesterly flow and a final upper shortwave swings through the region. Mainly cloudy skies with solid pops in the 40-60 percent range will be maintained, mainly across elevated terrain where orographic forcing will aid in boundary layer ascent supportive of snow shower activity. Considerably drier weather is expected in the valleys however with just a passing light rain or snow shower here or there. High temperatures continue seasonably cool in the 30s. By Saturday night clouds will hang tough in the mountains despite thinning moisture as weakening northwesterly flow persists with weak high pressure approaching from the Great Lakes. Valley locales should see some partial clearing after midnight however. Pops will continue to wane leaving just some scattered light snow showers or flurries across the highest of elevations by sunrise Sunday. Low temperatures mainly in the 20s. By Sunday high pressure will build across the region with sunny to partly sunny skies and light winds. Little airmass change is expected. In fact mean 925 mb thermal profiles actually cool slightly so high temperatures generally ranging through the 30s looks reasonable once again despite the added insolation. Winds light. Pops nil. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 300 AM EST Friday...Overall a fairly quiet period of sensible weather is expected during the Monday/Tuesday time frame with seasonably cool early December temperatures and only low chances of light precipitation, mainly across our western counties. Models remain generally consistent in tracking a dampening shortwave trough through the area on Monday into Monday evening with little fanfare. There will be a broad increase in cloudiness, though with weakening dynamical upper support and isentropic lift any precipitation should be light and scattered at best, most focused across our northern New York counties. By Tuesday high pressure returns to the region with partial sunshine and light winds. Again, negligible airmass change is expected with seasonal highs in the 30s both days and overnight lows in the 20s to around 30. Looking further out, this morning`s medium range guidance continues to suggest the mean flow trends more amplified across the lower 48 from mid-week onward as the year`s first decent polar airmass dives south into the Rockies and Northern Plains. This will eventually drive cyclogenesis across the Southern Plains/northwestern Gulf Coast which will track northeast toward the region. Still plenty of uncertainty in regard to how quickly this system will consolidate into a primary low pressure center with several solutions showing some sort of lead energy and associated precipitation affecting the area as soon as Tuesday night. At this point a blended solution appears most reasonable given this uncertainty, and will concentrate the bulk of higher precipitation chances during the Wednesday and Thursday time frame. Still too early to confidently predict p-type, though signals and synoptic pattern would suggest some sort of mix and/or rain seems most probable at this point as warm advective signatures increase solidly over time. Temperatures warm slightly during this period as mean background flow trends southerly with highs from the mid 30s to lower 40s or so, and lows in the mid 20s to lower 30s. && .AVIATION /15Z Friday THROUGH Tuesday/... Through 12Z Saturday...Generally VFR conditions out there this morning outside of KSLK where IFR cigs persist. Trend through the day though will be towards MVFR cigs, even at KSLK with some light rain showers developing during the early/mid afternoon. Brief reduction in vsby to MVFR is possible, but should mostly remain VFR. After 00Z, showers become more terrain focused so for almost all terminals should just be VCSH. Exception will be KSLK where freezing levels will fall low enough to support a transition to snow reducing vsby to IFR. Wind will be generally out of the west-southwest at 5-10kts with few gusts up towards 20kts at KMSS/KSLK. Outlook 12Z Saturday through Tuesday... 12Z Saturday through 12Z Sunday...Mix of VFR/MVFR with local IFR possible at KSLK in scattered rain/snow showers. 12Z Sunday through Tuesday...Mainly VFR with high pressure building in. Periods of MVFR ceilings possible, especially at KMPV/KSLK. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...WGH/Lahiff SHORT TERM...JMG LONG TERM...JMG AVIATION...Lahiff

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