Area Forecast Discussion
Issued by NWS Burlington, VT

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091 FXUS61 KBTV 270523 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 123 AM EDT Thu Oct 27 2016 .SYNOPSIS... Partial clearing and light winds are expected tonight as high pressure briefly settles over North Country. This will lead to chilly temperatures tonight, with lows generally in the 20s. The next low pressure system will approach from the Great Lakes later Thursday, with the primary low tracking into the St. Lawrence Valley before a secondary low takes over closer to the New England coast during Thursday night. After increasing cloudiness Thursday morning, looking for precipitation to develop Thursday afternoon and continue through Thursday night into Friday morning. After a brief rain/snow mix, precipitation will be predominantly rain at elevations below 2000 feet. Several inches of wet snow accumulation is possible at the higher summits. Total rainfall amounts generally a half inch to one inch, highest along the eastern slopes of the Adirondacks and Green Mountains. && .NEAR TERM /UNTIL 2 PM THIS AFTERNOON/...
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As of 109 AM EDT Thursday...Overall forecast in great shape early this morning with only a few minor tweaks to clouds and both hourly and expected low temps. The combination of departing mid level clouds from days of cyclonic flow and approaching high clouds from next system will result in mostly cloudy skies overnight. These clouds will tend to keep temps several degrees higher...with lows mainly near 20f slk/northeast kingdom valleys to lower 30s near lake champlain. Previous discussion...Mostly cloudy to cloudy conditions persist in NW flow, with lingering inversion near 5kft (per RAP soundings) helping to trap moisture and stratocu layer. Sfc ridge axis across sern Ontario will gradually shift ewd this evening into tonight. Effect will be for winds to become light and variable, and should see some partial clearing during after sunset. Depending on amount of clearing and radiational cooling, should be a chilly night. Certainly lows in the 20s for most sections. If skies can become mostly clear, may see a few readings in the teens for the nrn Adirondacks. Other than a lingering flurry across n-central into nern VT late this aftn, expecting dry conditions overnight. Dry conditions will be short-lived as next wave of low pressure approaches from the Great Lakes region on Thursday. Surface low will shift across Lake Erie/nwrn PA late Thursday morning, with increasing mid-upr clouds across our area. Leading surge of 850-700mb warm advection and associated precipitation arrives around 18Z across s-central VT and into the Adirondacks of NY. Precipitation will overspread the remainder of the North Country late in the afternoon...early evening for far nern VT. In terms of precipitation type, PBL will have a chance to warm out ahead of the arriving precipitation, generally into the low 40s. Anticipate some wet-bulb cooling with precip onset as column saturates, allowing for wet snowflakes as low as 500ft elevation mid- afternoon Thursday, but thereafter, looking at mainly a rain event below 1500ft with continued WAA and strengthening S-SE flow. Generally no snow accumulation at all below 1500 ft. May see a slushy coating to an inch 1500-2500ft. Above 2500ft, temps will hold on below freezing longer, and could see 4-8" across the highest summits of nrn NY and central/nrn VT through Thursday night. With a 50-kt sly low-level jet, there is a warm (above freezing) layer that comes in above summit level, so may see some periods of sleet as well into Thursday night. So, not expecting any impact for population/roadways, but the highest summits could see a moderate accumulation of wet snow based on current trends. Highs on Thursday generally in the low-mid 40s, and near freezing across the highest summits of VT and nrn NY. One other issue will be moderate winds on the western slopes of the Green Mtns, and across all of the higher terrain. SE winds peak during Thursday evening, and should see 15-25 mph with a few gusts 30-35mph possible along the immediate western slopes, as primary surface low tracks into the St. Lawrence Valley. Later Thursday night, gradient slackens as secondary low development takes place across sern new England...and should see sfc winds weaken. Stable low-level conditions will limit areal coverage of gusty winds to the immediate wrn slopes. Winds at summit level could reach 50mph consistent with model soundings closer to 4-5kft. In terms of total QPF, looking for some precipitation enhancement along the ern slopes of the Greens and into the ern slopes of the Adirondacks given low-level sely (upslope) conditions. Total rainfall amts ranging from 0.6" across the St. Lawrence and Champlain Valleys, but locally around 1" in aforementioned upslope flow areas, from Ludlow up to Bethel, and across portions of Essex/Clinton Counties in NY.
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&& .SHORT TERM /2 PM THIS AFTERNOON THROUGH FRIDAY NIGHT/... As of 328 PM EDT Wednesday...The potential low pressure system will be losing energy Friday morning as a shortwave vorticity maxima pushed the center of the low south and east from the Saint Lawrence to off the coast of New Hampshire. As this happens the warm air will continue to surge north and generally rain will be falling over the North Country except for a few higher elevation sites over the Adirondacks and northern edge of the spine of the Greens. By mid day northwest flow develops and there will still be some low level moisture at 925mb rh still exceeds 98% however moisture in the snow growth zone will be minimal so any snow/flurries will be confined to the areas with orographic lift. Friday should only see 0.10-0.20" of qpf across the eastern Vermont zones mainly falling as rain with a couple of hundredths of qpf across the rest of the north country. Snow totals will really be continued to elevations 2500-3000 feet and above and should only amount to an inch or two of additional accumulation of heavy wet on Friday adding to the 4-8 already from Thursday. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 357 PM EDT Wednesday...To start the weekend we will be under marginal warm air advection on Saturday. A ridge of high pressure will be slowly moving east in and 850 temps warm to +6C - +8C. Clouds will be increasing and thickening as a weak northern stream low tracks well to the north of the forecast area. With boundary layer temps warm and little cold air to speak of it will be just a typical late October rain event. QPF totals will be on the lower side but most of the area should see some light rain showers. Behind that low, a eastern conus ridge builds in and leads to dry air through the mid week before another low pressure system tracks just north of the Great Lakes and brings an additional chance for showers to start November. && .AVIATION /06Z Thursday THROUGH Monday/...
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Through 06z Friday...Several impacts to aviation expected over the next 24 hours associated with approaching storm system. Vfr conditions will prevail through 15z Thursday...with precip and mvfr cigs developing at MSS/SLK/RUT by 18z...with a period of wet snow providing intervals of ifr vis at slk. The precip overspreads PBG/BTV and MPV by 20z with mvfr cigs and potential brief period of ifr vis at MPV in -sn. Expecting mainly a cold rain by 00z at all taf sites with mvfr cigs...some ifr cigs are possible at MSS associated with northeast flow and MPV/SLK. Next concern is developing low level jet of 45 to 55 knots at 5000 feet lifting from southwest to northeast across our taf sites between 00z and 06z. This will create areas of turbulence and enhanced low level wind shear...especially when this jet interacts with the higher terrain. A few surface gusts between 30 and 35 knots can be expected at RUT between 00z-06z Friday with gusts up to 30 knots possible at BTV. Outlook 06z Friday through Monday... Precip will be slowly ending from southwest to northeast by 12z Friday with lingering upslope focused precip impacting mpv/slk. Profiles support mostly rain. As winds shift to the northwest on Friday morning...intervals of ifr cigs are possible at BTV/RUT/MPV/SLK...given the amounts of low level moisture available. A warm front feature lifting across our taf sites on Saturday morning will shift the winds to the southwest with some scattered showers possible...especially mss/slk. Expecting mainly vfr conditions with intervals of mvfr cigs possible across northern NY taf sites on Saturday. Gusty southwest up to 35 knots are possible at MSS with 30 knots expected at SLK/BTV on Saturday. Another wind shift to the west/northwest will occur Sat Night into Sunday with additional scattered showers. Drier conditions with vfr flight conditions for Sunday afternoon into Monday.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/Taber SHORT TERM...Deal LONG TERM...Deal AVIATION...Taber is the U.S. government's official web portal to all federal, state and local government web resources and services.