Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 281938 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 338 PM EDT Sun Aug 28 2016 .SYNOPSIS... The threat for showers and thunderstorms will increase across the area this afternoon and evening as an upper level trough of low pressure approaches from the west. Areas most likely to see the showers and storms will be across the northern Adirondacks of New York and the northern and central sections of Vermont. High temperatures will remain above normal today. Some showers will linger over the area Monday morning...but high pressure builds in and brings drier air and seasonable temperatures. && .NEAR TERM /THROUGH MONDAY/... As of 217 PM EDT Sunday...Current forecast in good shape. Composite radar loop showing some scattered rain showers developing over northern New York, mainly Clinton County at this time. Previous discussion from 652 AM EDT Sunday...Mid level moisture continues to move across northern New York and the northern half of Vermont this morning. There have been reports of sprinkles with these clouds and have added to the forecast for the next couple of hours. Otherwise...feel cloud cover will thin out mid-morning and allow temperatures to warm and eventually reach the upper 70s to mid 80s. This combined with dew points rising into the 60 to 65 degree range should help to create sufficient instability to enhance the convective potential. As usual the models are too high on the dew points and thus creating too much instability. Upper trough over the Great Lakes region will lift northeast today and thus dynamic support will be increasing over the area this afternoon. As trough approaches...deep layer shear will be increasing but will not be too strong. Feel enough ingredients exist for thunderstorms to develop this afternoon and evening...but none of them are strong enough to suggest storms become severe. Cannot rule out a strong storm or two however with gusty winds and heavy downpours being the main threats. Best potential for thunderstorms looks to be across the northern Adirondacks and the northern and central sections of Vermont. For tonight...areal coverage of showers and storms will be greatest during the evening hours...then quickly taper off after midnight as instability and forcing diminish. Lows will generally be in the 60s as plenty of low level moisture lingers over the region. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
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As of 335 PM EDT Sunday...Surface front will be along the New England coast Monday evening at the start of the short term period, with 500 mb shortwave trough exiting the coast. Surface high pressure and shortwave 500 mb ridging over the forecast area Monday night with dry air. Surface dewpoints fall into the 50s and 1000-500mb mean rh drops below 30 percent. With clear skies and light winds, good radiational cooling scenario, and lows Monday night in the mid/upper 40s in the Adirondacks and Northeast Kingdom, and 50s elsewhere. Will put in some patchy valley fog for the usual places Monday night as well for potential of radiational fog development. Southerly flow returns quickly Tuesday when high pressure shifts east of the area, and winds back in advance of next approaching trough. Dry air also shifts east, and precipitable water increases tuesday to around 1 1/4 inch, a little above normal. A weak surface trough will move out ahead of an approaching 500 mb shortwave trough and provide a focus for showers mainly in the north Tuesday night. Temps Tuesday in the lower 80s except upper 70s in the Northeast Kingdom of VT and Adirondacks, supported by 850mb temps around 13c. Warmer temps Tuesday night than Monday night with warmer southerly flow, cloud cover and higher dewpoints all to limit radiational cooling.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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As of 335 PM EDT Sunday...Wednesday is a transition day with ridge over the western US and flat trough in the east. 500 mb low moving through eastern Canada in northwest flow around the western ridge. Surface trough pushes on through the area Wednesday and is focus for afternoon convection, with upper trough lagging by 12 hours or so. Small amount of instability with capes near 500 j/kg. At this point will continue with just showers and no mention of thunder. Best chances for rain will be during the day Wednesday, and lingering Wednesday night over higher terrain in areas favored by upslope west to northwest low level flow. Cold front arrives Wednesday night, and upper trough carves out lower heights. Noticeably cooler and drier Thursday thru Saturday with nil rain chances for the remainder of the forecast period. 850mb temps near 5-6C supporting max surface temps in the 60s to around 70 depending on elevation. This will be a few degrees below their climatological normals for this time of year. Temperatures rebound late in the weekend with surface high shifting east for warmer southerly flow on Sunday. Building ridge in the east raises heights Saturday and Sunday, and 850 mb temps back to 12-14C, with max surface temps those days in the low 80s. Will see wide swings in temperatures the last half of the forecast period with clear skies and warm sunny days, and also clear skies and light winds at night conducive to good radiational cooling. Initially lows will be in the 40s and 50s Wednesday night, with a cooling trend for the remainder of the week. By Saturday morning patchy frost is possible at Saranac Lake and across the deeper valleys of the northeast kingdom. For Friday night/Saturday morning lows will range from the low to mid 30s to upper 40s...except mid 50s near lake champlain. Average 1st frost at SLK is Sept 7th...so pretty close to normal.
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&& .AVIATION /20Z Sunday THROUGH Friday/... Through 18Z Monday...Expecting showers and thunderstorms to develop across the region this afternoon into early this evening. Mainly VFR conditions expected with some areas of MVFR/IFR in showers and thunderstorms til 03Z Sunday. Some areas of IFR/MVFR in fog from mainly 05Z til 12Z Monday, especially in sheltered valley locations that receive rainfall this afternoon and this evening. Outlook 18Z Monday through Friday... 18Z Monday through Thursday...mainly VFR through 18Z Wednesday, as a ridge of high pressure builds into the region. Some areas of MVFR in scattered rain showers 18Z Wednesday through 00Z Thursday, as a cold front moves through the region. Mainly VFR Thursday and Friday, as a ridge of high pressure builds slowly southeast from Canada. && .MARINE... Winds will continue to increase out of the south today and reach the 15 to 25 knot range this afternoon and evening. Thus a lake wind advisory is in effect for this time period due to the stronger winds and choppy waters. In addition...the potential for thunderstorms will exist this afternoon and evening which will have the potential to produce gusty winds and heavy downpours. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Evenson NEAR TERM...Evenson/WGH SHORT TERM...Hanson LONG TERM...Hanson AVIATION...WGH MARINE...Evenson

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