Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 181028 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 628 AM EDT Tue Oct 18 2016 .SYNOPSIS... A warm front will lift north of the area today with unseasonably warm temperatures expected. A weak cold front with scattered showers will cross the area this evening and tonight. Mild and increasingly unsettled weather is expected across the area by Thursday into Friday, followed by much cooler, showery weather next weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 628 AM EDT Tuesday...Modest adjustments to hourly temperature and dewpoint trends as of 615 am to match current observational trends. Warm front has surged northward into most of the St Lawrence Valley, arcing across the Adirondacks into the Champlain Valley at this hour and continues to march northeast. Temperatures in the southern SLV are already in the mid to upper 60s in places like Wanakena, Edwards and Canton, with KBTV currently sitting at 64 with a 60 dewpoint. Meanwhile, KPB sits at 51F and KMSS remains with a light northeasterly flow sitting at 49 degrees. Given these stark disparities it will be difficult to exactly depict hourly evolution in these fields through the morning hours giving cloud cover, position of front and timing of pbl mixing. Nonetheless high temperature/wind/pop forecasts generally remain on track for this afternoon (see below). Have a great day. Prior discussion... An interesting day weatherwise across our area as a strong warm front lifts northeast through the area with very warm temperatures expected in many locales. Other than a scattered showers/isolated storms far north and east this morning, much of the day should trend very mild and dry as skies trend partly sunny in all but far northeastern counties. 24-hour back trajectory analysis at 21Z suggests source air arrives from southern Ohio in the Champlain Valley, and from near the KY/TN border across our northern NY counties. Values in these areas were in the lower to mid-80s yesterday, so readings in the upper 70s to lower 80s seem quite plausible from the Champlain Valley west this afternoon. Further east and north, the warm front will begin to slow as it encounters a more stubborn maritime airmass across eastern New England. In these northeastern counties clouds will likely linger a good portion of the day and keep resultant temperatures somewhat cooler (upper 60s to lower 70s). These values are still some 10 to 15 degrees above normal however. In addition to the mild temperatures, south/southwesterly winds will trend quite breezy to windy from the Champlain Valley west by this afternoon. Indeed, gusts into the 25-35 mph range will be likely in the Champlain Valley and Adirondacks with channeled flow boosting gusts into the 40-50 mph range in the SLV where a Wind Advisory is in effect from noon to 800 pm local time. By later this afternoon/early evening a weak cold front will approach from the northwest with scattered shower activity developing along an associated pre-frontal trough across northern NY counties. Given some nominal boundary layer instability and latest 3-hrly SREF/MOS t- progs have offered an outside shot of an isolated storm or two in these areas as well. Front then sinks through the area tonight with scattered showers/isolated storms as winds abate fairly quickly. Precipitation coverage should wane in coverage after midnight as front clears south. Larger-scale background flow remains deep southwesterly across and behind the boundary however, so an appreciable airmass change is not expected with lows generally holding on the mild side in the 50s to around 60.
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 415 AM EDT Tuesday...Cold front continues to depart to the east with the North Country. Westerly flow with cooler temperatures and dry conditions prevail for Wednesday and Wednesday night with brief period of surface high pressure over the region. Temperatures will remain above normal with maxes in the 60s and mins in the 40s. Clouds increase Wednesday night ahead of approaching low pressure system. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 502 AM EDT Tuesday...Pattern changes with potential long duration rain event. Mid-upper level trough will dig south and east from south central Canada, towards the Mississippi into the southern Ohio Valley late Thursday. At the surface, a low pressure system will gradually strengthen and bring a warm front into the North Country late Thursday. This low track up to Ohio River valley, continuing NEwd over PA by Friday morning. GFS and NAM depict strong area of frontogenetic forcing over portions of the North Country Friday. Mid level trough becomes negatively tilted late Friday as it interacts with coastal low followed by rapid strengthening of the surface low come Saturday morning. As the the surface low moves east into Maine, cold air filters in on NW flow. 540 thickness line moves into the area, indicating possibility for some snow showers Saturday morning, mainly in the higher elevations. Rain continues with possible breaks as dry slot may develop on Saturday. The low becomes closed and stacked during the day, with several pieces of vorticity embedded in cyclonic flow keeping a chance for precipitation through at least Sunday. Storm total QPF may vary widely based on where deformation zone develops Friday. && .AVIATION /12Z Tuesday THROUGH Saturday/... Through 06Z Wednesday...BKN/OVC VFR/MVFR prevalent through 12Z, then trending SCT/BKN VFR thereafter as warm front lifts through the region. Scattered showers may affect northern terminals 12Z or so with passage of front, with a return of showers possible late afternoon/evening (20Z onward) as cold front approaches from the west. A strong low level jet 30-40kts will develop late tonight into mid-morning over the Saint Lawrence Valley and with northeasterly drainage flow expect low level wind shear to be prominent at MSS from 09-14Z. Expect veering winds with the warm front gradually trending southeast 6-10 kts overnight and early morning. By mid morning tomorrow the low level jet will have moved over most of the North Country and winds across the Saint Lawrence and Champlain Valleys will become very gusty. Expect S-SW wind gusts of 25-35 kts developing at SLK/BTV by afternoon with sustained winds of 15-25 kts. At KMSS southwesterly gusts to 40 kts are possible. Outlook 06Z Wednesday through Saturday... 06z Wednesday - 12z Wednesday: VFR deteriorates to MVFR with showers along a cold front. 12z Wednesday - 00z Thursday: VFR under weak high pressure. 00z Thursday through Friday: Trending MVFR by 00z Thursday with MVFR to IFR at times through parts of Friday as steady rain advances northeastward. && .MARINE... A warm front lifting northward across the area this morning will allow increasingly strong southerly flow to develop on Lake Champlain by late morning into the afternoon hours. Sustained winds of 20 to 30 kts are expected with gusts to near 35 kts. This will create choppy to rough conditions on open waters and in bays/inlets with open southerly exposures. These conditions may pose a hazard to small craft and inexperienced mariners. A cold front will cross the area tonight with scattered showers as winds abate and veer to west/northwesterly over time. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...Wind Advisory from noon today to 8 PM EDT this evening for NYZ026-027-087. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...KGM LONG TERM...KGM AVIATION...JMG/Sisson MARINE...JMG is the U.S. government's official web portal to all federal, state and local government web resources and services.