Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 142325 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 725 PM EDT Mon Aug 14 2017 .SYNOPSIS... High pressure will keep the North Country dry through the first half of tonight. A weak warm front lifting northeast from western New York will bring increasing clouds during the pre- dawn hours, along with a few rain showers, mainly across northern New York. As a low pressure system deepens to our north we`ll see scattered showers and thunderstorms during the afternoon hours Tuesday. A few stronger storms are possible. The cold front moves through late Tuesday into Wednesday morning ushering in cooler temperatures for Wednesday and Wednesday night. Our next chance for showers and thunderstorms arrives on Friday. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 651 PM EDT Monday...A pleasant evening underway with daytime cumulus clouds decreasing as boundary layer temperatures cool. Will see light S-SW winds overnight with pleasant humidity levels (Dewpoints mostly in the low-mid 50s). There is a weak frontal zone and sfc convergence across Lake Ontario, and mosaic reflectivity indicates a few weak showers near vcnty of the bndry. Will see this frontal zone lift newd with weak 850-700mb warm advection after midnight. Should be mostly clear thru 04-06Z, followed by increasing cloud cover from SW-NE and potential for a few rain showers across nrn NY (PoPs 20-30 percent). It appears the increase in cloud cover and winds 10-20kts just above the bndry layer will preclude fog in most locations overnight. The only exception might be the deeper valleys of far ern VT. Lows overnight will fall into the mid 50s to low 60s in the valleys. The forecast challenge in the near term is what happens on Tuesday aftn. Energy from a vort will lift through the Adirondacks during the overnight hours early Tuesday morning and with orographic lift should be enough to cause some showers to move up through the Adirondacks and into the Northeast Kingdom. During the morning hours, warm air advection and diurnal heating should warm the North Country to the low 80s. Those temps combined with dewpoints increasing to the upper 50s to low 60s should mean there will be plenty of instability to initiate some storms. NCAR ensembles show quite a bit of scattered 40dbz composite reflectivity values but no distinct locations. The best downdraft CAPE is well to our south with the best signal over the Mohawk valley and along the MA/VT border. We will be right in the nose of the right rear quadrant of a robust 250mb jet so there will be ample divergence aloft for any of the storms that do develop. As such, I`ve followed the lead of SPC`s marginal risk and included the mention of gusty winds for the forecast area during the afternoon hours Tuesday. I dont anticipate any widespread severe activity but rather a storm or two that could become storm and produce strong winds. The front then clears through the North Country overnight and we see a return of northwest flow aloft and cold air advection although we shouldn`t cool much more than Monday night as our lows will be in the mid to upper 50s. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 400 PM EDT Monday...There will be a chance for some light rain showers Wed morning as upper level shortwave crosses the region. By Wednesday afternoon and into the overnight hours drier air will be moving into the North Country with ridge of surface high pressure building into the area out of the North. Cooler air will also be moving into the area for this time period. Winds will be gusty out of the Northwest. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 410 PM EDT Monday...Dry weather will continue for Thursday and the first part of Thursday night ahead of next approaching system. On Friday a low pressure system will lift from the Northern Great Lakes region northeastward into Central Quebec by early Saturday morning. Have likely pops mentioned across the CWA for Friday and the first part of Friday night. Drier weather is expected for Saturday, though upper level trough will linger a bit behind this system. Some showery weather remains as this upper trough pushes eastward across our forecast area, but drier weather will return from Sunday night through Tuesday with another ridge of surface high pressure ridging into the area. && .AVIATION /23Z MONDAY THROUGH SATURDAY/... Through 00Z Wednesday...Mainly VFR expected through the TAF period. A short period of MVFR cigs possible as low stratus may develop just around sunrise lasting until mid-morning in the St. Lawrence Valley (KMSS) and western Adirondacks(SLK). Can`t rule out an isolated shower or rumble of thunder in that area during that time frame with some elevated instability but not enough confidence to include in the TAFs. Elsewhere just some sct low and broken mid-level clouds are expected to move into the region by morning. Left fog out of the TAFs at this point due to a tightening pressure gradient and increasing boundary layer winds overnight and relatively low cross-over temps. Additional showers and scattered thunderstorms develop by midday into the afternoon Tue so included showers but left TS out because confidence of a storm hitting any individual TAF location is low at this point. Winds will generally be light or southerly less than 10 kt overnight but around 10 kt or a bit more at KBTV on Tuesday. Outlook... Tuesday Night: VFR. Scattered SHRA...Scattered TSRA. Wednesday: VFR. Slight Chance SHRA. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX. Thursday Night: VFR. Slight Chance SHRA. Friday: VFR/MVFR. Likely SHRA. Friday Night: VFR/MVFR. Chance SHRA...Slight Chance TSRA. Saturday: VFR/MVFR. Chance SHRA...Slight Chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Banacos/Deal SHORT TERM...Neiles LONG TERM...Neiles AVIATION...Sisson

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