Area Forecast Discussion
Issued by NWS Burlington, VT

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857 FXUS61 KBTV 260228 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1028 PM EDT Tue Oct 25 2016 .SYNOPSIS... Low pressure over the Canadian Maritimes will maintain cloudy conditions and a few snow showers across the higher terrain of the Adirondacks and northern Vermont through tonight. High pressure building in from the west will yield lighter wind speeds and some additional sunny breaks during the day Wednesday. It will remain seasonably cold with afternoon highs in the upper 30s to lower 40s in most areas. A widespread precipitation event is expected later Thursday into Friday as low pressure approaches from the Great Lakes and Ohio Valley region. Precipitation type will be predominantly rain in the valleys, but some snow accumulation or mixed precipitation is likely in the mountains at times Thursday night into Friday morning. && .NEAR TERM /UNTIL 11 AM WEDNESDAY MORNING/... As of 1027 PM EDT Tuesday...Infrared satellite shows persistent broken to overcast stratocumulus in the northwesterly gradient flow regime across the North Country, with radar still showing weak reflectivities in and around the mountains. However, more breaks in the overcast are evident northwest of YUL. As the overnight progresses, we should begin to see a trend toward less cloud cover, though not fully cloud-free which should allow for temps to cool more quickly than they presently are. A general decrease in area coverage of mountain snow showers should also result as RH in snow growth layer begins to drop. All these trends well handled in going forecast with only noise-level adjustments made. Previous near-term discussion issued at 200 pm Tuesday follows... Continue to see some weak reflectivity returns associated with shallow instability showers in NW flow across nwrn and n-central VT. At 18Z, boundary layer is warm enough to generally yield rain in the Champlain Valley (38-42F), but seeing some intermittent light snow in surface obs across n-central into nern VT in sfc obs and available wx cams. Road surfaces are above freezing, so not anticipating any travel issues through this evening. Freezing levels this afternoon generally around 1500ft, and will gradually fall to around 500ft by 06Z tonight. Will see continued chances of upslope snow showers thru the first half of tonight, with a dusting to 0.5" possible in communities east of the Green Mtns. Could see a max of 1-2" at the higher summits of the nrn Greens, including Jay Peak and Mt. Mansfield. Thereafter, anticipate some low-level drying, and majority of mesoscale models indicate decreasing precip chances per simulated reflectivity fields. Moderate NW winds this afternoon (10-15kt with gusts around 20kt), will generally decrease overnight to 5-10kt, with little change in direction. Combination of continued stratus/stratocu and winds will keep temps from dropping too significantly; looking at overnight lows upr 20s to lower 30s, warmest near Lake Champlain. Generally going with a dry forecast Wednesday as surface high pressure builds ewd into nrn NY by afternoon. May see a few flurries far nern VT. Weaker p-gradient will also result in lighter winds, mainly 6-10mph. Decreasing low-level RH fields suggest we`ll see some additional sunny breaks, especially away from the higher terrain areas. 850mb temps at 18Z Wed still -9C to -10C, so will remain colder than normal for late October. Valley highs mostly 40-44F, with a few upr 30s far nern VT and across the nrn Adirondacks. && .SHORT TERM /11 AM WEDNESDAY MORNING THROUGH THURSDAY/... As of 331 PM EDT Tuesday...Wednesday night will remain quiet as a brief area of high pressure will move through the North Country. Clouds cover will be slowly decreasing with a few breaks likely working in but we will stay partly to mostly cloudy throughout. Cold air advection will remain in place and overnight lows will be on the chilly side will low 20s in the typical cold locations of the Northeast Kingdom and northern Adirondacks. Along Lake Champlain and the nearby locations temps will be in the upper 20s to low 30s. Thursday clouds will thicken as a low pressure system begins to dig in to the north country. Cold air will remain in place over the eastern portion of the forecast area as we will be in cold air daming situation with the high pressure over eastern Canada and the deepening low over the Great Lakes. The system looks fairly strong as a warm front will bring some warm advection snow Thursday morning before switching over to rainfall for all locations below 2500`. Above 2500 expect a mix of snow and mixed precip for the duration as the max t aloft hovers right at 0C or below. Guidance continues to show a strong 850mb southerly jet that develops during the day on Thursday however the max winds will coincide with the heaviest precip so mixing wont be all that strong. Downslope winds on the northern facing mountains will likely be in the 20-30mph range. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... As of 359 PM EDT Tuesday...Overnight Thursday the ptype forecast become a bit more tricky. Guidance shows a warm nose slightly above 0C at 925-850mb works in after 00z and this coupled with marginally warm boundary layer temps supports rain in the deeper valleys and a mixed bag of rain/snow/sleet/freezing rain across the Adirondacks and eastern Vermont. As the low pushes east on Friday, thermal profiles become more supportive of a transition back to snow elevations above 1000ft, but the boundary layer remains too warm at the surface supporting showers/rain as precip becomes more orographic in nature on developing northwest flow. Early thoughts on storm totals through Friday show the highest elevations with the highest snow totals in the 6-8" range along the spine of the Green Mountain with 8-12" across the high peaks of the Adirondacks. Elsewhere expect between a dusting to 2 inches. Next system looks to swing through Saturday through Saturday night, taking a more northern track than its predecessor, offering even warmer thermal profiles, enough to produce mainly rain showers with highs pushing into the mid/upper 40s. Behind it, high pressure looks to return for Sunday night into Monday. && .AVIATION /02Z Wednesday THROUGH Sunday/... Through 00z Thursday...BKN-OVC for most of area tonight but some SCT at times across St. Lawrence Vly (KMSS). Ceilings generally around 4kft (VFR), but will see MVFR ceilings possibly redevelop with passing flurries or light snow showers at KSLK/KMPV to occur thru the first half of tonight (04Z Wed). Decreasing clouds and becoming VFR all areas after 15Z Wednesday. Winds 5-10kts tonight into Wednesday. Outlook 00z Thursday through Sunday...Primarily VFR through 15Z Thursday with high pressure in place. Low pressure approaching from the ern Great Lakes and Ohio Valley will bring prevailing MVFR with intervals of IFR possible later Thursday thru early Friday. Will see valley rain, and possible snow/mixed pcpn at times for SLK/MPV during the event. After a brief break Friday aftn/night, a warm front approaching from the WSW could bring additional showers Saturday into Saturday night. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/Loconto SHORT TERM...Deal LONG TERM...Deal AVIATION...SLW is the U.S. government's official web portal to all federal, state and local government web resources and services.