Area Forecast Discussion
Issued by NWS Burlington, VT

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868 FXUS61 KBTV 222315 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 715 PM EDT Sat Jul 22 2017 .SYNOPSIS... An isolated shower or thunderstorm remains possible this evening across the northern Adirondacks and south-central Vermont. Otherwise, high pressure across Quebec will bring light north winds and dry conditions overnight and through the daylight hours on Sunday. Our chances for showers increase as an upper level trough will bring widespread showers to the North Country beginning Sunday night and lasting through Monday and into Monday night. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 709 PM EDT Saturday...At 2305Z, regional composite reflectivity still showing isold shower activity across Essex County NY ewd across central/s-central VT. Have adjusted PoPs to account for this activity, which should generally dissipate after 02-03Z with loss of daytime heating. Into the overnight hours, high pressure across Quebec will generally be in control with light northerly winds. Dewpoints are a few degrees lower than 24 hrs ago, and will be dealing with some mid-upr level cloudiness overnight, especially across s-central VT. As a result, fog should be relatively limited compared to last night. With high pressure in firm control Sunday expect another quiet day to start. The upper level trough will still be east of the the Great Lakes mid day so while clouds should be on the increase during the day, precip will be slower to arrive. The flow aloft will be generally northwest with northeasterly surface flow. The weak cool air advection and increase cloud cover should only allow the temps to warm to the mid 70s on Sunday. Heading into the evening hours the upper level clouds low will continue to track over the Great lakes and a meso low will develop over Lake Ontario. That meso low will ramp up shower activity quickly and should lead to widespread showers over northern New York late Sunday night. && .SHORT TERM /MONDAY THROUGH TUESDAY/... As of 332 PM EDT Saturday...Low pressure system will bring showers and possible thunderstorms to the North Country Monday through Tuesday. Surface low pressure will approach from the southwest as a mid level trough digs into the eastern Great Lakes during the day Monday. PWATs will climb to around 1.25" as low level deformation increases with approaching low. While moist environment will be in place, CAPE will be lacking over most of VT and 500-1000 J/kg over northern NY on Monday. Expect thunderstorms to affect northern NY with just showers over VT. SE to easterly winds around 925-850mb could result in some downsloping and slightly less POPs in the leeward valleys. Overcast skies, rain showers, and decreasing 925mb temperatures on Monday, expect maxes in the 60s. Monday night into Tuesday will see surface low near Lake Ontario translate some of its energy to a coastal low off the Jersey coast. While this coastal low takes the bulk of moisture with it ENEwd out to sea, the 500mb trough will move across the North Country on Tuesday, resulting in more showers. Temperatures still below normal with Monday nigh min in the 50s and Tuesday max in the upper 60s to mid 70s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 332 PM EDT Saturday...Expect the 500mb trough to move east of VT by 00Z Wednesday with high pressure building at the surface. Clearing skies Tuesday night could lead to areas of patchy fog. Drier air filters in with PWATs falling to 0.5-0.75 Tuesday night into Wednesday. Wednesday will be dry and warmer with maxes in the mid 70s to around 80. Ridge of surface high pressure slides east Wednesday night, putting the North Country in south to southwest flow. A surface cold front is progged to move into the St Lawrence Valley for the latter half of Thursday, producing showers and thunderstorms. This will continue into Thursday night as the cold front continues to cross the region. Model guidance diverges as the ECMWF stalls the frontal boundary over New England Friday as energy rides along the front and develops into a surface low. This low strengths and moves northward over western New England resulting in a wet weekend. On the other hand, the GFS builds high pressure into northern New England through the rest of the period. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... Through 18Z Sunday...Mainly VFR conditions are expected through the period. SCT-BKN cirrus deck around 20kft will continue to stream over the area today with some fair weather cumulus developing over the mountains. A weak frontal boundary may provide an isolated shower or storm across southern Vermont through the evening but the chances remain small so I opted not include any mention of VCSH. As we lose the diurnal heating, the fair weather cu will dissipate and we should go back to partly cloudy skies. IFR fog still remains a possibility for SLK/MPV and the feeling is that visibility`s will jump up and down with periods of mvfr/ifr 2-4SM visibility`s generally between 8z- 11z. Outlook... Sunday Night: VFR. Chance SHRA. Monday: MVFR. Likely SHRA...Slight Chance TSRA. Monday Night: VFR/MVFR. Likely SHRA...Slight Chance TSRA. Tuesday: VFR/MVFR. Chance SHRA. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. Chance SHRA...Slight Chance TSRA. Thursday: VFR/MVFR. Likely SHRA...Likely TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Banacos/Deal SHORT TERM...KGM LONG TERM...KGM AVIATION...Deal is the U.S. government's official web portal to all federal, state and local government web resources and services.