Area Forecast Discussion
Issued by NWS Burlington, VT

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753 FXUS61 KBTV 241812 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 212 PM EDT Mon Oct 24 2016 .SYNOPSIS... The North Country will remain in cyclonic flow with variable cloudiness and cooler than normal temperatures through most of the week. A secondary trough moving into the region from the northwest late today will bring a chance of light rain showers, with snow showers possible across the northern Adirondacks and northern Green Mountains through Tuesday night. A more significant wave of low pressure approaching from the Great Lakes and Ohio Valley will bring the next chance for rain, generally late Thursday into early Friday. && .NEAR TERM /THROUGH TUESDAY/...
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As of 150 PM EDT Monday...Overall quiet weather, but variably cloudy conditions will continue today in broad cyclonic flow, still influenced by the closed, slow-moving low pressure system over ern Quebec and Labrador. Will again see gusty surface winds, generally from the WNW, at 10-20mph, with gusts to 25-28mph through this afternoon. Wind gusts will be aided by steep lapse rates promoting turbulent mixing. Associated shallow instability will continue to produce stratocu clouds, which will be most prevalent across the higher terrain of nrn NY and central/nrn VT. Water vapor imagery showing weak shortwaves embedded in 500mb flow that looks to affect the North Country with slight to low chance for rain showers, especially in upslope and higher terrain areas of Green Mtns and Adirondacks this afternoon but more so overnight. Areas above 1500 feet likely to see snow showers mixing with mostly snow expected above 2000ft (freezing levels generally around 2500ft this aftn and eve, falling to 1500-2000ft late this eve and overnight). With dewpoint temps in the 20s overnight, can`t rule out a couple wet flakes in the valleys. Light snowfall accumulations expected this afternoon and overnight...generally a dusting to 2 inches in the highest elevations of n-central into nern VT. Temperatures today look to peak today in the mid 40s to around 50 for most areas, but generally 40-45F in the 1-2kft elevational band. Overnight lows will range from the upper 20s to mid 30s.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 400 AM EDT Monday...A 1 to 2 STD below normal mid/upper height field associated with a trof across the northeast CONUS will continue to provide our region with below normal temps through midweek. The combination of favorable 925mb to 850mb upslope flow and ribbons of deeper layer moisture associated with cyclonic circulation will continue to produce terrain focused precipitation through Tuesday. The associated low level wind fields are between 20 and 30 knots on Tuesday result in limited low level forcing from upslope component...but weak embedded vort at 500mb and some low level cold air advection will be enough to produce light qpf across the mountains. Will mention likely pops for Tuesday...with qpf generally 0.20 or less across the northern dacks and western slopes...with only a trace to couple hundredths in the valleys. Thermal profiles show both 925mb and 850mb temps below 0c...with 850mb temps near -10c by 00z Weds...supporting mostly snow...except the valleys and near the warmer Lake. Speaking of Lake Champlain...some enhanced precipitation is possible on the east side of the lake with moderate instability created between the air/water temp difference...especially on Tuesday. Also...noted with boundary layer heating and cold air aloft...lapse rates steepen on Tuesday afternoon...supporting some convective elements with potential graupel in the valley. Thinking any snow accumulation below 1000 feet will be difficult during the daytime...but some minor accumulation above 1000 feet between a dusting to several inches is likely across the northern dacks and mountains of central/northern VT. Its never too early to start building the snow pack. Thermal profiles support about a 20 degree difference between lower/mid 20s mountains summits to lower/mid 40s valleys on both Tuesday and Weds...with lows mainly upper teens to lower 30s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 400 AM EDT Monday...Active pattern continues for days 4 thru 7 with additional chances for rain and snow on Thursday into Friday and another system next weekend. Overall...given the progressive west to northwest flow aloft...temps will stay below normal thru the period with additional chances to increase snow pack across the mountains...especially Thursday Afternoon. GFS/GEM and ECMWF in good agreement with potent 5h energy in the northern jet stream crossing the Great Lakes and NE CONUS on Thursday into Friday. Meanwhile...initial surface low pres tracks across the central Great Lakes with weak secondary development over southern New England by 12z Friday. The combination of 1036mb high pres over eastern Canada and developing secondary low pres...suggests warmer air will have difficulties advecting into our region...supporting potential for additional snow accumulations in the mountains. Sea level pres fields show a cold air damming signature. Latest ECMWF only briefly increases the 850mb temps to 0c around 06z Friday...before winds shift to the northwest and colder air follows. Current thinking a band of rain/mixed with wet snow flakes develops from southwest to northeast on Thursday...associated with moderate to strong warm air advection. The combination of evaporational cooling and progged 925mb to 850mb profiles below 0c initially supports even some wet flakes in the valley with no accumulation...before quickly turning over to rain. Meanwhile...cold air remains locked east of the greens and across the northeast kingdom with a longer duration of snow...with several inches of wet snow accumulation possible Thursday afternoon/evening...before changing over to rain. Mountain thermal profiles are tricky as progged 850mb temps stay near 0c...but warm nose around 5000 feet associated with southerly jet...supports some freezing rain possible near the summits of the dacks and greens on Thursday Night. It shall be interesting to see what the picnic table on Mansfield receives. Otherwise...the potential for gusty downslope southeast winds will have to be latest GFS shows 850mb winds of 40 to 50 knots. The strongest winds are collocated when precip will be falling and difficult to determine how much mixing will occur...but something to watch along the western slopes on Thursday afternoon/evening. Next system arrives late Saturday into Sunday with additional chances for precipitation and once again thermal profiles support mainly rain valleys and a mix in the 850mb 0c line bisects the area. Temps during the period mainly in the 30s mountains and 40s valleys with lows in the 20s to mid/upper 30s. && .AVIATION /18Z Monday THROUGH Saturday/...
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Through 18z Tuesday...Persistent W-NW flow will bring variably cloudy conditions, but mainly VFR (ceilings 3.5-5kft) at the TAF locations. Sole exception should be at SLK, which will occasionally see ceilings 2-3 KFT. Visibility generally unrestricted with gusty/well-mixed low-level conditions. Will see a few orographic showers/snow showers develop as we head into tonight thru Tuesday morning. This may bring some VSBY restrictions vcnty of the HIR TRRN. Also, may see brief MVFR at SLK in snow showers toward daybreak. W-NW winds will remain moderately strong...12-15kt with gusts to 25kt thru sunset. Winds will diminish somewhat overnight (8-10kt), then increase to similar speeds (12-15ktG25kt) from the NW during the daylight hours Tuesday. Outlook 18z Tuesday through Saturday... 18Z Tuesday through 12Z Wednesday: Isold/sct rain and snow showers will persist vcnty of the nrn Adirondacks/nrn Greens Tuesday aftn into first half of Tuesday night. Could see intervals of MVFR conditions at SLK, and possibly also at MPV. At the remaining TAF sites, BKN-OVC conditions but with VFR ceilings expected. Winds NW 8-15kts. 12Z Wednesday Through 12Z Thursday: Surface high pressure across the region will bring generally VFR conditions and lighter winds. 12Z Thursday Through Saturday: Low pressure system approaching from the Great Lakes/Ohio Valley brings developing rain Thursday afternoon into Thursday night, with MVFR and intervals of IFR conditions possible. After a brief break on Friday, another wave of low pressure brings additional showers and possible MVFR conditions on Saturday.
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&& .MARINE... AS OF 420 AM EDT MONDAY...A Lake Wind Advisory goes into effect for Lake Champlain this afternoon. Winds out of the west at 10 to 20 knots today will shift northwest and increase to 15 to 25 knots this afternoon. This will result in choppy waters as wave heights increase to 2 to 4 feet with the highest waves along eastern shores exposed to a greater fetch on northwest winds; specifically those locations adjacent to the open waters north of the Charlotte Ferry and south of Valcour Island. Expect these strong winds and waves to continue into tonight. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Taber LONG TERM...Taber AVIATION...Banacos MARINE...KGM is the U.S. government's official web portal to all federal, state and local government web resources and services.