Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 210732 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 332 AM EDT Sun Aug 21 2016 .SYNOPSIS... A cold front across southeastern Ontario and western New York this morning will shift eastward, crossing the North Country this afternoon and evening. Gusty south winds will occur in advance of the front through early afternoon, followed by widespread showers and a few thunderstorms as the frontal rainband moves through mid afternoon through the evening. Some showers will produce locally heavy downpours. On Monday, high pressure returns bringing cooler temperatures and drier weather. Weather will remain dry through Thursday with high pressure in control, along with a gradual moderation in temperatures. && .NEAR TERM /THROUGH TONIGHT/... As of 239 AM EDT Sunday...Forecast generally on track. Active period of weather expected as vigorous shortwave trough across WI/upper MI at 07Z begins to make its way ewd with increasing large-scale forcing across the North Country by this afternoon. Generally dry and breezy this A.M., but a period of moderate to briefly heavy rain is expected later this afternoon into the first half of tonight. Attendant cold front across sern Ontario early this morning will shift into nrn NY by 00z Monday, and then sweep eastward across the North Country and east of the CT River Valley by 06Z Monday. Strong sea- level pressure gradient in place this morning across the North Country ahead of frontal system, along with 2-3kft winds of 40-45kts based on KTYX VAD. Should translate into widespread southerly surface winds of 15-25mph, with gusts to 30 mph, and locally 35 mph in the Champlain Valley morning through mid- afternoon with channeled flow. A lake wind advisory has been posted for Lake Champlain. Southerly flow in advance of approaching frontal system will rapidly increase PW values, reaching 1.6-1.7" by early afternoon, and around 2" along the cold front late in the afternoon/evening hours. SBCAPE is limited due to lapse rates near moist adiabatic, but values around 500 J/kg should be sufficient for some embedded thunderstorms, producing brief heavy downpours. In terms of timing, appears pre-frontal trough and associated showers begins affecting the St. Lawrence Valley 16-18Z, and slowly shifts across the Adirondacks into the Champlain Valley by 21Z. Bulk of rainfall for the Champlain Valley and points east will be between 21-03Z, and then ending from west to east by 06z Mon with strengthening mid- level wswly flow accelerating frontal motion overnight. Will generally see 0.5 to 1.0" rainfall amts, but locally higher with any embedded tstms. That said, motion of cold front appears progressive enough that we should avoid any hydro related problems. High temperatures this afternoon upr 70s to lower 80s with abundant mid- upr clouds followed by rain showers later in the day. Lower clouds have developed east of the Green mountains with moisture return, and will keep temps generally in the mid-upr 70s. Temps cooler quickly during the pre-dawn hours Monday with westerly wind shift and increasing low-level cold air advection. Lows generally in the 55-60F range across VT, but lower 50s across nrn NY. && .SHORT TERM /MONDAY THROUGH TUESDAY/...
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As of 332 AM EDT Sunday...Upper trough is exiting the area to the east Monday morning...but there may still be some lingering showers east of the Green Mountains in the morning. Northwest flow in the low and mid levels will promote cold air advection and below normal temperatures are expected with highs in the mid 60s to lower 70s. High pressure builds in Monday night and with clear skies and light winds...looking at below normal temperatures to continue with lows in the lower 40s to lower 50s. This shot of below normal temperatures will be short lived as temperatures quickly rebound to seasonal normals on Tuesday with plenty of sunshine and no precipitation expected.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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As of 332 AM EDT Sunday...The warming trend that began on Tuesday will continue into Wednesday and Thursday as southwest flow aloft becomes established over the region. Highs will be in the low to mid 80s both days. Dry weather will continue Wednesday into the first half of Thursday before a trough of low pressure moves in Thursday night and Friday. This will allow for increasing clouds and the chance of showers and thunderstorms Thursday night into Friday. High pressure follows in behind the trough of low pressure on Saturday for drier weather and slightly below normal temperatures.
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&& .AVIATION /07Z Sunday THROUGH Thursday/... Through 12Z Monday...Cold front approaching from SE Ontario and wrn NY will bring an active period of weather, especially 18Z Sunday through 06Z Monday. Early this morning, increasing S-SE winds occurring as pressure gradient intensifies. South winds 10-15kts expected areawide, and should see gusts to 25kt at BTV through 18Z Sunday associated with channeled flow in the Champlain Valley. Increasing low-level moisture is bringing MVFR ceilings along/east of the Green mtns, and expect this to be the case through the day, with HIR TRRN OBSCD. Elsewhere, VFR with lowering ceilings from west-to-east as front approaches from the west this afternoon. Should see scattered showers affecting MSS/SLK toward 18Z, and into the Champlain Valley by 21Z, and RUT/MPV toward 00Z Monday. Generally MVFR conditions late afternoon through evening within frontal rainband. Intervals of IFR possible with embedded heavy downpours, and with isold thunderstorms. Winds shift into the west and Northwest with FROPA overnight, and showers tapering off from west to east after 06Z Monday. Strong frontal inversion and trapped low-level moisture suggests areas of MVFR ceilings will persist through 12Z Monday with HIR TRRN OBSCD. NOTE: Rutland AWOS (RUT) is not operating. Because of the lack of disseminated observations, we continue our suspension of amendments for the RUT TAF. Once the communication problem has been resolved, and we again get routine observations automatically transmitted, we will lift that restriction. Outlook 12Z Monday through Thursday...High pres in place with mainly VFR conditions. Only exception will be LIFR fog possible MPV/SLK 06-13Z each morning. && .MARINE... As of 200 AM EDT Sunday...Southerly winds continue to increase this morning with strengthening pressure gradient in advance of surface cold front across sern Ontario/wrn NY. Will generally see sustained south winds 20-30kts across Lake Champlain through early to mid-aftn, before subsiding with onset of rain showers as frontal rainband moves into the region from the west. Showers will contain heavy downpours this afternoon, and a few thunderstorms are also possible late afternoon into early evening. Those planning on boating today should be aware of the strong south winds and potential for heavy rain showers later in the day. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Evenson LONG TERM...Evenson AVIATION...Banacos MARINE...Banacos

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