Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 260544 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 144 AM EDT Thu Apr 26 2018 .SYNOPSIS... Areas of low pressure will affect the area through the upcoming weekend with near seasonable temperatures and a periodic threat of showers. Fair and much warmer weather returns to the region by the early to middle portions of next week as strong high pressure builds across the eastern half of the nation. && .NEAR TERM /THROUGH TONIGHT/... As of 1249 AM EDT Thursday...Area of showers across Vermont early this morning is lifting northeast and should exit the area in a couple hours. Meanwhile some showers to our south may move back in but it will take the upper circulation near the western portions of Lake Ontario to move east and increase dynamic support for a redevelopment of precipitation across northern New York toward sunrise. Have tweaked precipitation chances to fit this scenario...otherwise rest of forecast in good shape with plenty of cloud cover and temperatures falling little from current readings. Previous discussion below: The forecast remain on track as we head into the evening hours. Our first wave of light rain is now lifting into northern counties while a distinct dry slot surges northward in advance of a slowly approaching upper shortwave trough across the eastern Great Lakes. Our area will largely lie within the dry slot regime this evening into the first half of tonight, and as such precipitation will trend more scattered and showery in nature with areal pops lowering into the chance category - especially for the eastern half of the forecast area. By later tonight the aforementioned upper trough pivots into the area with a general redevelopment of activity later tonight. Low temperatures a blend of available guidance - mainly 40s. The upper trough then swings through the area during the morning hours on Thursday as bands of showers pivot east to west across the area - especially north. The central core of this feature is fairly compact with rather cool thermal profiles in the 700-500 mb level. This, along with good PVA and moisture convergence on the front nose of this feature warrants higher pops in the 60-80 percent range through the morning hours, again most concentrated across northern counties. By afternoon the main upper feature begins to exit east so pops gradually wane toward evening. Highs to run quite similar to today as winds trend light westerly over time - mainly 50s with a few upper 40s across the Adirondacks. A brief window of drier weather then arrives for Thursday night as weak shortwave ridging evolves between the departing trough and additional energy taking shape across the southeast. Given broad consistency in this idea among this morning`s models a mainly rain- free night is expected as skies trend partly cloudy over time. Low temperatures a tad cooler in the upper 30s to lower 40s in general. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 348 PM EDT Wednesday...Friday morning will start off dry as shortwave ridging builds in, however some showery precipitation will spread northward throughout the afternoon as a surface low lifts out of the southeastern United States. Models continue to struggle to come to a consensus on the track of this low, with the GFS remaining steadfast in the furthest west track, while the previous outlier ECMWF has come into better line with the NAM/GEM track that takes the low up the coast. By Friday afternoon however, models are coming to better agreement that the aforementioned low will become absorbed into the broader longwave trough, phasing to some extent with northern stream energy rounding the trough from central Canada. As multiple shortwaves gyrate within the base of the broader longwave trough over the northeastern US, the North Country will see an extended period of showery weather through Saturday. It looks like the entire Friday through Saturday time period certainly won`t be one big washout, but rather on and off showery precipitation closely tied to individual shortwaves. These features are notoriously difficult to time this far out, so have stuck with chance PoPs for this time period, but expect to have a better handle of timing/location of individual waves within the next few forecast packages. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 348 PM EDT Wednesday...The generally unsettled weather will continue Saturday night through Sunday night as the dynamic upper-level trough remains over the Northeast. The trough will also bring a shot of cooler air that will limit temperatures Sunday from climbing above the upper 40s/low 50s. The cold air advection will also support a well mixed boundary layer during the day time hours, so Sunday afternoon will feel a little breezy. The pattern shifts Monday morning however as the trough pushes east and expansive ridging pushes in from the west. Southwesterly return flow around a building surface high to our south will support a warming trend for the first half of the work week. Everything is still on track for us to see temps in the upper 50s/low 60s Monday, then into the low to mid 70s for Tuesday and Wednesday. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... Through 06z Friday...Precipitation has lifted northeast of the area early this morning...but deep moisture remains over the area. This is resulting in a wide variety of conditions with general MVFR ceilings and visibilities expected through about 14z...but there will be frequent periods before 14z where IFR and LIFR conditions are expected. Eventually after 14z an upper level low pressure system will move in from the west and mixing will take place as southwest winds develop at speeds around 10 knots. This will help lift ceilings and visibilities into the VFR and MVFR categories. At the same time showers will be numerous across the area through about 00z before the upper level low pressure system moves east and precipitation comes to an end with VFR visibilities for the remainder of the period. Ceilings after 00z should also be in the VFR category. Outlook... Friday: VFR. Chance SHRA. Friday Night: MVFR/IFR conditions possible. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with local IFR possible. Chance SHRA, Chance SHSN. Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA. Sunday Night: Mainly MVFR, with local IFR possible. Slight chance SHRA, Slight chance SHSN. Monday: Mainly MVFR, with areas VFR possible. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...Evenson/JMG SHORT TERM...RSD LONG TERM...RSD AVIATION...Evenson

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