Area Forecast Discussion
Issued by NWS Burlington, VT

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009 FXUS61 KBTV 170603 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 103 AM EST Fri Nov 17 2017 .SYNOPSIS... Colder air will is moving into the region today with snow showers tapering off early this morning except lingering in all the mountains for until midday. Falling temperatures and accumulating snow in the mountains and their western slopes will yield a some icy roads for the morning commute on Friday. Dry weather returns for this afternoon as a weak area of high pressure moves in. The next low pressure system brings another round of rain and snow along with gusty winds for Saturday night and Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 102 AM EST Friday...Current forecast on track, just a few tweaks to temperatures and winds which are gusting over 30 knots from the NW. Secondary 700mb trough and associated surface cold front has shifted east of the Champlain Valley at 0315Z. Developing WNWLY flow behind the front and frontal inversion is beginning to result in orographic blocking, with enhanced reflectivity developing along the nrn slopes of the Adirondacks and across the Champlain Valley into the wrn slopes of the Green Mtns. This trend should continue thru the remainder of the overnight hrs. Concurrently, low-level CAA will allow temperature profiles to cool enough to change rain over to snow. Already down to 28F with light snow at SLK, and should see temperatures near freezing at BTV by 10Z. May see some developing icy spots on roadways for the morning commute, especially across the wrn slopes of the Green Mtns where orographic enhancement and cooling temps will combine the most favorably. No significant changes to snowfall amts through 12Z...generally a coating to 0.5" across the northern valleys. May see first measurable snow of the season at BTV. Could see 2-3" for the higher summits from Camels Hump to Mt. Mansfield to Jay Peak. Some snow showers linger across central and northern Vermont going into Friday mid-day, but by the afternoon sunshine should break out as high pressure builds in across the mid-Atlantic and Northeast states. Winds remain brisk from the northwest, and this combined with air temps topping out in the 30s will create some decent wind chills through the day in the teens and 20s. The high centers over the region Friday night with clearing skies for the first half of the night, and some high clouds building in from the west ahead of our next system. Shouldn`t affect temps from plummeting into the teens and 20s area-wide with some single digits possible in the Adirondacks and Northeast Kingdom, while warm air advection riding in aloft will keep the highest peaks in the 20s warming into the lower 30s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 358 PM EST Thursday...On Saturday a large low pressure system is set to impact the North Country. The system is expected to bring a mix of rain/snow/sleet as it progresses into the region with a return to snow as the system exits Sunday night. The 500mb trough on Saturday will be amplifying into a full latitude trough with a deepening surface low over the Ohio Valley region. That low will track northeast through Lake Erie and Ontario into the Saint Lawrence valley or just north. The surface track will lead to warm air advection surging into the North Country on Saturday along with the leading edge of the precip shield. Guidance continues to back off on the timing of precip and so I`ve pulled back the arrival of precip until mid to late afternoon on Saturday. With the delayed timing, there`s an increasing chance for the warmer nose aloft to work into the region and cause some mixed precip to fall. Given uncertainty in timing, I`ve continued to just mention the boundary layer impacts of either rain or snow because its a tad early to feel confident in specific mixed precip type. By Saturday evening the warm air will be fully into the area and full melting will occur with rain expected for the bulk of the overnight hours. The surface low should be just over the Saint Lawrence valley Sunday morning and there`s growing evidence that the dry slot may work into the forecast area by early Sunday morning. The impact of this is two fold, one our precip could come to an end early, and second the pressure driven winds will start to see some mixing of the stronger low level jet. Based on the latest blends of guidance I`ve indicated gusts of 35-45 mph will be possible in the Saint Lawrence with 30-35 across the rest of the Champlain Valley and Vermont. Much of this will be dependent on how much mixing occurs and the stability of the region. The cold front clears the North Country Sunday afternoon and cold air aloft returns switching any remain precip back to snow. With northwest flow aloft the western slopes should pick up some measurable snow due to orographic effects. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 423 PM EST Thursday...High pressure builds into the North Country to start the work week and other than a weak clipper expected to bring some lake effect snow over Northern New York the longer term forecast remains quiet with near normal temps which will be beneficial for travel during the holidays. The clipper system has some potent energy but much of that stays too far north to impact the forecast area. Expect Lake Effect snow with some orographic enhancement on Wednesday into Wednesday evening with a return to dry weather for Thanksgiving Afternoon/Evening. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Through 06Z Saturday...Mainly MVFR with periods of IFR vsby at times through about 10z or so. Precipitation will be mainly ties to the higher terrain, affecting KSLK and KMPV the most, but will also occasionally make it into BTV and other valley locations. Falling temps may lead to icy runways by morning. Between 13-15Z Friday conditions will trend back to VFR as high pressure builds in. Winds will also be a factor through the period, gusty from the northwest with gusts 20-30kts likely until about sunset then winds go light and variable with SKC-SCT250. Outlook... Saturday: Mainly VFR, with local MVFR possible. Likely SHRA, Chance SHSN. Saturday Night: Mainly MVFR, with local IFR possible. Likely SHRA, Likely SHSN. Sunday: Mainly MVFR, with local IFR possible. Windy with gusts to 35 kt. Chance SHRA, Chance SHSN. Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHSN. Monday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Monday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Tuesday: Mainly VFR, with areas MVFR possible. Slight chance SHRA, Slight chance SHSN. Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHSN, Chance SHRA. && .MARINE... As of 102 AM EST Friday...A Lake Wind Advisory remains in effect for today. Winds will be northwest and gusty at 20 to 30 knots through mid-afternoon as cold air pours over the 50 degree lake waters leading to a very unstable boundary layer hence the gustiness. Anyone out boating will need to be aware of the rough conditions that will result from the strong winds. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Sisson NEAR TERM...Sisson SHORT TERM...Deal LONG TERM...Deal AVIATION...Sisson MARINE...Sisson is the U.S. government's official web portal to all federal, state and local government web resources and services.