565 FXUS61 KBTV 060518 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 118 AM EDT Wed Oct 6 2021 .SYNOPSIS... High pressure located over southern Canada will slowly build into the North Country tonight into Wednesday. This will result in a clearing trend with mostly sunny skies developing by Wednesday afternoon. Some areas of patchy fog are likely tonight as temperatures cool back into the 40s and 50s. A prolonged period of warm and dry conditions can be anticipated for the remainder of this week into early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 112 AM EDT Wednesday...Clouds continue to slowly decrease in areal coverage near the International Border this morning, but fog/br is quickly developing. PBG scattered out and within 15 to 20 mins fog/br developed. Expect this trend to continue acrs the central/northern CPV and parts of northern NY thru early Weds morning. Did bump temps up another degree or two, given dwpts are in the mid 50s most locations. Rest of fcst in good shape. Previous Discussion...The forecast challenge tonight is clouds and impacts on fog/br potential and temps. Crnt GOES-16 vis satl imagery shows widespread clouds acrs our fa with some breaks over the northern SLV and parts of central VT. Water vapor shows large scale drying in the mid/upper lvl directly overhead, indicating moisture is trapped below stubborn subsidence inversion. Expecting clouds to linger in most locations overnight, which wl kept temps from reaching cross over values and limit fog/br production. However, thinking some clearing develops acrs the SLV, northern CPV, and parts of central/northern VT to allow temps to reach cross over values with some br/fog development likely toward midnight. Have continued to mention threat in grids from 04z-12z Weds. Temps are tricky, but have trended on the warmer side of guidance based on anticipated clouds, which support mid 40s to mid 50s, but if clearing develops NEK or SLK, l/m 30s would be possible. On Weds, soundings show deeper dry layer with 1000 to 850mb rh mixing out as drier air aloft works toward the sfc. Expect increasing amounts of sunshine as 1029mb high pres builds directly overhead. Progged 925mb temps btwn 11-13c at 18z Weds, supports highs well into the mid 60s to lower 70s most locations. A clear night with calm winds expected on Weds night as high pres is directly overhead. Expect a sharp fall in temps with some patchy fog likely, especially dacks and central/eastern VT valleys. Have trended toward the cooler side of guidance with clear skies and light winds expected, lows mid/upper 30s to lower 50s. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... As of 354 PM EDT Tuesday...With high pressure overhead, attention is towards fog and daily temperature. Areas of dense fog will redevelop overnight into early daytime hours with lack of boundary layer winds and active vegetation areawide persisting without a hard freeze occurring so far this season. Forecast currently has all of the favored river valleys fogging in, with expected small dewpoint depressions given the excellent cooling conditions will also lead to areas of fog elsewhere. With the thermal ridge sliding to our southwest a bit on Friday, it looks like the back door cold front may slip into our area sooner rather than later. No precipitation is expected with its passage, but winds will become more easterly by late in the day. Boundary layer winds will be light to support shallow mixing each day, minimizing potential high temperatures. The air mass will still be plenty warm to achieve above normal highs in the low 70s in most places each day along with plenty of sunshine. With midday dew points mainly 50-55, low temperatures will drop below crossover values into the 45-50 range most spots, which will still be roughly 10 degrees above average for this time of year. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 354 PM EDT Tuesday...More active, but low impact, weather is expected during the long term period. It will be noticeably windier, especially over Lake Champlain, over the weekend with channeled southerly flow. These winds will be supported by the squeeze play of strong high pressure migrating southward from eastern Canada and deepening low pressure over the northerly Plains states, with deep southwesterly flow aloft in between. However, upper level energy will tend to focus precipitation north and west of our area through this period. As such, low chances for precipitation are indicated at this time. At some point early next week there should be a period of widespread showers, but if the flow amplifies as much as the latest model guidance suggests, mainly dry and unseasonably warm conditions will prevail through Tuesday. Moist advection will lead to ample clouds, especially from Sunday onward over most of the area. It still looks like localized drizzly and cool weather in the lower Connecticut River Valley is probable on Saturday given the moist southeasterly flow, especially in the morning, around the aforementioned high pressure system to our east. Temperatures will be tricky during this period with the push and pull of unseasonably warm air mass with the lowering sun angle and potential of cloudy skies. Therefore, the model blend utilized suggests temperatures tending to remain about 10 degrees above normal, or trending even milder for lows given the effect of increasing winds and cloud cover. && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/... Through 06Z Thursday...Crnt obs show a wide range of flight categories from vfr at btv/mpv/efk to mvfr at pbg/rut to ifr/lifr at slk/mss. Trends will be for fog/br to develop or persist at mss/slk/pbg with ifr/lifr thru 12z, while fog/br with intervals of ifr conditions are expected at btv aft 08z and toward 10z at rut/mpv and efk. Conditions wl slowly improve from ifr/lifr to mvfr and vfr at all sites by 16z Weds. Winds remain light and variable thru the entire 24 hour period. Outlook... Thursday: VFR. NO SIG WX. Thursday Night: VFR. Patchy BR. Friday: VFR. Patchy BR. Friday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: VFR. Chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...Kutikoff LONG TERM...Kutikoff AVIATION...Taber