Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 020440 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1140 PM EST Thu Dec 1 2016 .SYNOPSIS... A closed upper low over southern Quebec will keep the north country in cyclonic flow through Saturday, with cloudy skies and chances for rain and snow showers from tonight through Saturday. A ridge of high pressure will build into the region on Sunday, with fair and dry weather expected from Sunday through Tuesday. && .NEAR TERM /UNTIL 6 PM FRIDAY EVENING/...
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As of 1031 PM EST Thursday...No significant changes with the late evening update. The closed, quasi-stationary mid-level low over swrn Quebec will maintain a moist cyclonic flow regime across the North Country overnight and during the day on Friday. Prevailing surface to 800mb winds will continue from the WSW overnight into Friday...which will be favorable for upslope snow shower activity in the nrn Adirondacks and central/nrn Green Mtns, but not offer much in the way of low-level CAA with trajectories coming from the open waters of the ern Great Lakes. Thus, temperatures will generally stay a bit too warm for snow shower activity in the valley locations. Will continue to see ISOLD/SCT light rain showers in the valleys, with more frequent rain/snow shower activity across the higher elevations of the nrn Adirondacks and central/nrn Green Mtns with more favorable orographic ascent. At 0330Z, mosaic composite reflectivity and surface observations indicate light snow shower activity at SLK, and light rain MVL/MPV/EFK/CDA, with snow levels generally around 1500-2000ft in the nrn Green Mtns. Should see snow levels fall slightly to 1000-1500ft during the overnight hours, with a coating to 2" possible above 1500ft or so overnight. Also, it appears there is a shortwave trough across southeastern Ontario, which will rotate across the region during the pre-dawn should see a bit of an increase in areal coverage of shower activity after 06Z, and indicated some increase in PoPs accordingly. Temperatures not falling much from current readings thru the remainder of the night. Other than some downslope clearing in the CT river valley, mainly overcast skies and west-southwest winds will help to keep temperatures above freezing overnight. MOS guidance looks too cold for overnight min temperatures, so have leaned toward the warmer GFS LAMP mos guidance for min temperatures overnight. Winds will stay up overnight and this combined with the cloud cover will keep temperatures several degrees warmer than MOS guidance overnight. On Friday, the North Country will continue to be under the influence of the closed upper low over southern Quebec which will keep in cloud cover, along with chances for rain and snow showers. Snow showers will be mainly confined to the higher elevations of the Adirondacks and Green Mountains where additional accumulations of 1-3" are possible for the higher summits of nrn NY and VT. Highs will be mainly in the low- mid 40s on Friday, except locally in the mid- upr 30s for the nrn Adirondacks.
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&& .SHORT TERM /6 PM FRIDAY EVENING THROUGH SATURDAY NIGHT/... As of 311 PM EST Thursday...500mb trough moves through the region Friday night with snow showers expected about 1000ft and above and rain/snow mix at lower elevations transitioning to snow for the latter half of the night. Min temperatures will randing from the mid 20s to low 30s. As surface low pushes eastward toward the Canadian maritimes, a ridge of high pressure builds across the lower Ohio valley, putting the north country in NW flow. This will result in precipitation becoming more orographic by Saturday morning. FROUDE numbers of 0.5 to 1 indicate slow moving blocked flow on Saturday, helping to focus snowfall on western slopes and in the higher terrain. There`s a chance for brief disruption in flow late in the day as 500mb vort swings across the North Country, providing a slight chance to chance of mostly snow across the forecast area. Max temperatures on Saturday will remain in the 30s. Saturday night the surface ridge shifts eastward over the eastern Great Lakes by Sunday morning. Moisture over the North Country looks to diminish from top to bottom with lingering clouds under inversion. Expect snow showers to end by daybreak. Forecast snowfall totals throughout the short term are a dusting to quarter inch in the broad valleys, with few tenths of an inch to 3 inches in the higher elevations. Min temperatures generally in the 20s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 311 PM EST Thursday...High pressure is the dominant feature Sunday and Sunday night, resulting in a brief period of dry weather. Remaining under light northerly flow, temperatures remain cooler Sunday with maxes in the 20s to mid 30s. Min temperatures will range from the mid teens to mid 20s Sunday night. Another mid level trough arrives Monday morning, weakening as it moves across the region and resulting in only chance POPs as ridging returns Monday night. With max temperatures in the 30s, generally expect light snow showers. A more significant system takes form Tuesday, bringing in precipitation from the south and west. Still much disagreement among models, but as initial precip looks to be the result of warm air advection/warm front, there`s a chance for mixed precipitation Tuesday night into Wednesday. GFS shows southern stream low develop into closed coastal low moving near the 70/40 benchmark as another surface low associated with very large 500mb trough approaches the region from the west. 12Z ECMWF not available at time of forecast for comparison. && .AVIATION /06Z Friday THROUGH Tuesday/...
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Through 06Z Saturday...Little overall change in aviation weather conditions as a moist WSW flow remains in place south of closed upper low over wrn Quebec. Expecting surface winds to continue W-WSW at 5-10kts...increasing slightly during the late morning through afternoon hours on Friday (10-12kts, with a few gusts 16-18kts). Ceilings start VFR (3-5kft) BTV/PBG/RUT and MVFR (1-3kft) at KSLK/MPV/MSS with favorable moist flow from Lake Ontario combined with upslope effects. It appears ceilings will lower somewhat later Friday afternoon into Friday night as upper trough rotates sewd across the area. That will bring prevailing MVFR conditions. HIR TRRN will remain OBSCD throughout the period. In terms of precipitation, not expecting anything significant through 18Z, with passing valley sprinkles/showers, and higher elevation snow showers at SLK with occasional 3-5SM vsby. Mid-level trough brings better chance for widespread shower activity later Friday into Friday night. Outlook 06Z Saturday through Tuesday... 06Z Saturday through 18Z Sunday...Upper trough remains in control with BKN-OVC skies, and general mix of MVFR/VFR ceilings. Will see some additional chances for mainly light snow showers, mainly with orographic effects at SLK/MPV. HIR TRRN generally OBSCD. 18Z Sunday through Tuesday...Mainly VFR with high pressure building in from the west. Can`t rule out lingering MVFR ceilings vcnty mtns, including SLK/MPV Taf locations.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...WGH NEAR TERM...Banacos/WGH SHORT TERM...KGM LONG TERM...KGM AVIATION...Banacos is the U.S. government's official web portal to all federal, state and local government web resources and services.