Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 291949 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 249 PM EST Tue Nov 29 2016 .SYNOPSIS...
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An initial wave of low pressure will exit to our north and east this evening, allowing steady precipitation to end from west to east early tonight. Skies will remain cloudy with patchy drizzle and fog developing overnight. Another wave of low pressure and associated warm front will bring additional moderate rainfall to the North Country Wednesday afternoon through Wednesday night, along with locally gusty south to southeast winds. Rainfall amounts between a half and three- quarters of an inch are generally expected. A large upper trough will then persist across New York and New England, providing mostly cloudy skies and chances for rain showers Thursday and Friday, and scattered snow showers for the weekend.
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As of 206 PM EST Tuesday...Will allow the Freezing Rain Advisory to expire on time at 21Z with temps generally above freezing as of 19Z across central/ern VT. Just a couple of mesonet sites and KVSF still at 32F, with just a chance of some ice still around on untreated surfaces, especially in the deeper/more sheltered valleys. Elsewhere, temps have generally risen into the low-mid 40s, except locally in the upr 30s with nely terrain channeled flow locked in across the immediate St Lawrence Valley of far northern New York. Per IR satellite imagery, initial shortwave trough is exiting to the north and east at 1930Z. Rainfall as already ended generally across the St. Lawrence Valley and nrn Adirondacks, and anticipate back edge of rainfall to shift slowly ewd per mesoscale model suite. Generally looking for -RA to end in the Champlain Valley around 00Z, and eventually end across central/ern VT 01-03Z. Once this happens, sea-level pressure field becomes nearly flat across our region, and weak flow regime with saturated conditions will prevail thru the remainder of the overnight hrs into Wed morning. Looking at continued low stratus deck, with some patchy drizzle and fog expected...right thru 14-15Z Wednesday with little flow to mix out near surface inversion layer. Temps quasi-steady tonight, mainly holding in the upper 30s to lower 40s. Meanwhile...developing surface low across the upper Ohio Valley and ewd extending, strong warm front will be lifting nwd across PA at 15Z Wed, with the warm front reaching central NY and wrn MA by 21Z Wed. Strong low- level WAA and isentropic ascent will overspread the North Country from south to north Wednesday afternoon into Wednesday evening, with surface low tracking to our west into southeastern Ontario during Wednesday night. PoPs near 100% Wednesday evening with periods of moderate rain expected. Total rainfall by 12Z Thursday generally 0.50-0.75", but 900-800mb SE flow increasing to 50-60kts will allow for some orographic enhancement on the ern slopes of the Greens, where localized 1" amts are expected. Mild temps on Wednesday...with highs mainly mid-upr 40s, and lower 40s for Wednesday night. Only other issue will be possible period of gusty winds, as SE 925mb flow increases to 40-45kts around 00-03Z Thu, per 12Z NAM, just in advance of the warm front. Anticipate steady rainfall during this time frame, which tends to lead to stable PBL conditions mitigating downward mixing and momentum transfer. Did include some SE winds 20-25mph with gusts to 35mph on the immediate wrn slopes of the Green Mtns with possible downslope effects. Otherwise, higher gusts should be confined to the exposed higher terrain areas of the Green Mtns into the nrn Adirondacks, peaking during Wednesday evening. As surface low moves past, will see a band of strong SWLY 925mb winds of 45-50kts moving across the St. Lawrence Valley. This may also cause some gusty winds to 35-40mph around KMSS and the surrounding St. Lawrence Valley toward daybreak on Thursday. Will continue to monitor.
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&& .SHORT TERM /THURSDAY THROUGH WEDNESDAY NIGHT/... As of 341 AM EST Tuesday...Overall very little change for the middle of the week from previous forecasts as low pressure centered over the Minnesota/Wisconsin border Wednesday morning moves very slowly east over the central Great Lakes by Thursday morning. After a dry but cloudy Wednesday morning, well advertised second wave of low pressure develops along the attending cold frontal boundary extending south/southwest from the Ohio Valley to the Gulf of Mexico, and quickly shifts into the Northeast states by the afternoon accompanied by another round of widespread rainfall with temps continuing above normal in the low 40s east to low 50s west. Rain continues into the first half of Wednesday night as well, until deep layer moisture shifts east of the region after midnight and is replaced by a mid-level dry slot. Some concern is developing for a brief period of southeasterly downslope winds Wednesday evening ahead of the frontal passage as a strong 925-850mb jet of 40-50kts traverses the area, but timing will be critical and current progs indicate mixing will be limited by precipitation during the late afternoon and evening hours. If precipitation moves through faster and the jet is delayed slightly, the potential for 40-50mph gusts will exist, but for now have just highlighted 30-40mph in the climo favored downslope regions along the western slope of the Greens and Adirondacks. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 341 AM EST Tuesday...Unsettled weather continues to be the theme for extended forecast with the aforementioned deep low dominating the North Country`s weather through the weekend as it slowly tracks eastward through southern Quebec Thursday/Friday, and offshore Saturday. Surface cold front shifts east of the area Thursday morning but the mid level flow remains out of the southwest supporting some lake enhanced rain/snow showers, before turning to the west/northwest for Friday and the weekend where a return of more seasonal temperatures and periods of off and on orographic rain/snow showers are expected each day. Finally by Sunday night and Monday, a brief period of surface high pressure and ridging aloft looks to build in, with some sunshine possible to start the work week. && .AVIATION /19Z Tuesday THROUGH Sunday/... Through 18Z Wednesday...Widespread IFR-MVFR conditions through the period. Light rain and patchy freezing rain far eastern VT will gradually end from west to east late this afternoon/evening. Will see prevailing low stratus and patchy fog overnight with diminishing winds areawide and TRRN OBSCD. Generally expecting widespread IFR 04-14Z Wednesday, with some improvement back to VFR possible locally at BTV 14-18Z Wednesday. Most other TAF locations should remain IFR/MVFR. Warm front approaching from the south with the next frontal wave will bring developing rainfall from south to north right at the end of the TAF period. Included VCSH at SLK/RUT for this developing rain, but majority will hold off until beyond 18Z Wednesday. Outlook 18Z Wednesday through Sunday...Widespread moderate rainfall with combination of MVFR/IFR conditions 18Z Wed through 12Z Thursday. Also, localized SE wind gusts in excess of 25kts possible KRUT 23Z Wed thru 05Z Thu, along with areas of LLWS areawide. Isold to sct showers remain possible Thu/Fri with VFR/MVFR conditions, followed by isold/sct snow showers Friday night through Sunday with continued VFR-MVFR conditions, and perhaps brief IFR with passing snow showers at TAF locations. && .MARINE... As of 343 AM EST Tuesday...A LAKE WIND ADVISORY is in effect for the open waters of Lake Champlain today. South to southeasterly winds will briefly increase to 15 to 25 knots along the passage of a warm front today. Winds will likely peak around mid-day to early afternoon, before lowering below 15 knots early this evening. Small vessels should exercise caution if heading out on Lake Champlain today, as forecast winds will create choppy conditions with waves possibly as high as 4 feet for a brief period. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Freezing Rain Advisory until 4 PM EST this afternoon for VTZ003-004-006>008-010-012. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Banacos MARINE...Lahiff is the U.S. government's official web portal to all federal, state and local government web resources and services.