167 FXUS61 KBTV 280000 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 700 PM EST Fri Nov 27 2020 .SYNOPSIS... Rather dreary conditions will continue through tonight as low stratus clouds remain firmly in place with some patchy drizzle. A weak cold front passing tonight through Saturday will favor continued drizzly weather through Saturday morning, although clouds should begin to break some by Saturday afternoon and may finally see a few peaks of sunshine later in the day. High pressure for Sunday will keep the area dry with increasing sun. A strong low pressure system tracking to our west will bring rain and windy conditions Monday into Tuesday. && .NEAR TERM /THROUGH SATURDAY NIGHT/... As of 700 PM EST Friday...The forecast remains in great shape as we head into the evening hours. The only change was to increase cloud cover to mainly 100% overcast for much of the night through mid-morning on Saturday based off new model guidance and current observational data. Otherwise patchy drizzle/very light showers, light winds and seasonably mild late November temperatures look to be the rule overnight. Have a great evening. Prior discussion... Main story for the near term forecast continues to be persistent low stratus and areas of drizzle as low-level moisture remains trapped near the surface under a strong mid- level subsidence inversion. A weak cold front will move through overnight tonight into tomorrow, which will allow for some mid- level cooling overnight and steepening of lapse rates under the inversion. However, not expecting much change in the clouds overnight with forecast soundings indicating moisture remaining trapped near the surface and potential for areas of drizzle overnight into Saturday as the front moves trough. May see some very localized freezing drizzle in higher elevations of the Greens/Adirondacks and parts of the Northeast Kingdom overnight, but the remainder of the forecast area will remain above freezing and thus no impacts expected. By the time Saturday afternoon rolls around, may see just enough mixing in parts of the Champlain Valley and southeastern VT to see clouds break a bit and allow in some sun. This is further supported by Froude numbers finally approaching 1 for the first time in a few days, indicating an end to the highly blocked pattern we've seen since midweek. Higher elevations, however, will hold on to clouds and maybe even some drizzle through the day Saturday. Highs Saturday will be in the low to mid 40s. Lows Saturday night will be in the upper 20s to mid 30s. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... Other than the potential for a few sprinkles during the pre-dawn hours, Sunday is shaping up to a quiet yet seasonably cool day across the North Country. In the wake of the cold front seen on Saturday, high pressure will build overhead and help scour out any lingering moisture. This will allow for a clearing trend to be observed across the region with partly to mostly sunny skies prevailing during the afternoon hours. Temperatures on Sunday will warm into the upper 30s to mid 40s under these clearing skies which should make for a very nice late November day. Don't get too used the sun, however, as we will see a thick blanket of cloud cover move over the region Sunday as the next storm system approaches from the southwest. && .LONG TERM /MONDAY THROUGH FRIDAY/... We expect to see a phasing of the northern and southern jet stream energy Monday morning across the Mid-Atlantic which is expected to yield a strengthening area of low pressure. This system is expected to track across western Pennsylvania and ultimately across the western and central Great Lakes. By the late morning hours on Monday, a warm front will begin to lift across southern Vermont with strong isentropic lift and frontogenesis expected along the leading edge of the frontal boundary. This should yield a period of light to moderate rainfall across the region as the front lifts north. Our rainfall rates will be somewhat limited as the moist conveyor belt transporting the highest PWAT values will remain offshore. Nevertheless, the dynamics in the low to mid-levels are expected to help compensate by creating efficient rainfall processes. During the late afternoon and evening hours, there is good model consensus that a dry slot will develop across Vermont as a strong southeast to northwest oriented low level jet moves overhead. Based on the NAM12 and BTV4, this low level jet is expected to be in the 70 to 80 knot range which is quite strong especially when we see these winds coming from the southeast. In addition, the dry slot is expected to allow for additional warming which should help increase our low level lapse rates. All of this in turn could create some strong and gusty winds across the western slopes of the mountains as well as the mountaintops. Based on the guidance we have now, it looks like winds in the 35 to 45 mph will be common along the western slopes of the Green Mountains Monday afternoon and evening but the potential for even stronger winds exist. These stronger winds will be tied to the stability of the air mass as the potential for downsloping winds and/or mountain waves cannot be ruled out until we get closer to the event and can analyze the stability with higher resolution model guidance. The good news is these stronger winds should only last 3-5 hours and not all day as the low level jet will quickly shift to the north and east. Additional rain showers are expected through the night Monday into Tuesday as the upper level low slides slowly eastward. As this upper low tracks further east Tuesday night into Wednesday we will see rain showers transition over to snow showers with a couple inches of snow accumulation possible; especially at higher elevations. It'll take some time for the upper low to finally exit to the east so we are generally carrying 30-40 percent PoPs through much of the extended as no days next week look totally dry but they aren't expected to be overly wet either. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... Through 00Z Sunday...Low ceilings remain the primary aviation forecast challenge as low-level moisture is stuck in place thanks to a building subsidence inversion in the mid- levels. Ceilings will genrally be better than last night but still primarily IFR/MVFR ceilings through 15z. Will also see areas of drizzle and mist with the frontal passage. Gradual lifting of ceilings expected after 15Z. Winds will be light and variable through the 12-15z but a slight west component around 5-7kts aft 16-18z with perhaps some SCT skies in the Champlain Vly aft 20z. Outlook... Saturday Night: VFR. Slight chance FZDZ. Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: Mainly VFR, with areas MVFR possible. Windy with gusts to 35 kt. Definite RA. Monday Night: Mainly MVFR, with areas IFR possible. Definite RA, Numerous SHRA. Tuesday: Mainly MVFR, with local IFR possible. Scattered SHRA. Tuesday Night: Mainly MVFR, with areas VFR possible. Scattered SHRA, Scattered SHSN. Wednesday: Mainly MVFR, with areas VFR possible. Isolated SHRA, Isolated SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Duell NEAR TERM...JMG/Duell SHORT TERM...Clay LONG TERM...Clay AVIATION...SLW/Duell