Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 240223 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1023 PM EDT Fri Oct 23 2020 .SYNOPSIS... A cold front will move through Saturday morning, which will bring a few rain showers and falling temperatures through the weekend behind the front. After a dry and seasonably cold Sunday, wet weather will arrive by Monday morning across the entire area. Temperatures will stay below normal during most of next week. && .NEAR TERM /THROUGH SATURDAY NIGHT/... As of 1020 PM EDT Friday...Updated pops again to better capture broken line of rain showers with embedded rumbles of thunder approaching the SLV. Thinking convection is limited acrs our fa, as instability/dynamics are waning. Also, have bumped hrly temps/dwpts up by several degrees, as MSS is crntly 71 and BTV is holding at 68. Combination of southerly winds and increasing clouds ahead of cold front is helping to hold temps steady, before falling sharply after fropa later tonight into Saturday Morning. Still anticipating some localized gusts up to 30 knots acrs the SLV/dacks and parts of the CPV overnight before fropa. Changeable wx anticipated acrs our cwa, as a sharp cold frnt will swing thru the fa tonight into Saturday. The general idea of best s/w energy passing to our northwest still holds, while sharp convergence and good ribbon of mid lvl moisture with boundary produces a band of showers from west to east acrs our fa. This precip will impact slv after 04z, dacks btwn 06-08z, cpv 08z-12z, and thru most of vt by 16z, besides some lingering upslope precip. Overall qpf will generally be in the 0.05 to 0.25 range with highest values over the SLV. Have sharpened up the pop fields overnight, along with making some minor adjustments to hrly temps. Combination of southerly winds and advancing clouds will keep temps on the mild side overnight, until boundary sweeps through. Otherwise, fcst in good shape. Previous discussion below Was overall a very warm and breezy day today for the North Country, with highs in the low to mid 70s across northern NY and the Champlain Valley. Meanwhile east of the Greens, onshore southerly flow led to persistent marine stratus which has kept central and eastern Vermont in the upper 50s to mid 60s today. Southerly winds with some gusts 15 to 25 mph this afternoon will weaken some this evening, then strengthen again towards midnight as a southwesterly low-level jet moves overhead. Temperatures will decrease through the night tonight, but lows will still be relatively mild in the mid to upper 50s for much of Vermont and the Champlain Valley of NY. Low stratus clouds over eastern Vermont are expected to once again thicken and lower tonight. Meanwhile, a front will approach from the west overnight which will spread some mid and low-level clouds over northern NY during the early morning hours of Saturday. The front will be somewhere in the vicinity of the Saint Lawrence Valley around sunrise, thus lows will be colder in the Saint Lawrence Valley than elsewhere Saturday morning. As the front moves eastward during the late morning hours of Saturday, temperatures will continue to drop over the northern Adirondacks and the Champlain Valley, and high temperatures will be observed early in the day before the boundary goes through. There will be some rain associated with the frontal passage. Rain will start shortly after midnight over northern NY, then diminish into just some light showers as the front progresses eastward into Vermont during the late morning hours. Despite the expected showers with the frontal passage, Saturday will by no means be a washout, and total QPF amounts will only be in the 0.01 to 0.25 inch range. Highest amounts (generally 0.10 to 0.25 inch) are expected over the Saint Lawrence Valley into the northern Adirondacks, along with the higher elevations of the Green Mountains. Lower amounts (0.01 to 0.10 inches) are expected in lower elevations of the Champlain Valley and eastern Vermont. The front will clear the area by Saturday evening, and skies will generally trend less cloudy overnight. There may be some low-level moisture trapped near the surface which would lead to some low- clouds overnight despite drier air moving in aloft. However, expecting most of the cloud cover to dissipate towards sunrise, which would lead to rapid nocturnal heat loss with light winds as high pressure builds in. Overnight lows Saturday night will be in the mid 20s to mid 30s. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... As of 326 PM EDT Friday...Sunday is shaping up to be the coldest day of the fall thus far as cold air continues to filter in behind the cold front that moved through the region on Saturday. After seeing morning lows in the mid 20s to mid 30s, temperatures will struggle to climb into the lower to mid 40s; even with filtered sunlight. High pressure throughout the day should yield light winds and dry weather but an increase in precipitation chances will be seen late Sunday night as a shortwave tracks northeastward along the eastern periphery of the positively tilted upper level trough. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 326 PM EDT Friday...A cold, rainy and snowy day is in store for the North Country on Monday as a potent shortwave tracks across the region. It looks like a burst of snow can be expected across northern New York early Monday morning as all guidance shows the vertical thermal profiles initially below freezing. As the morning progresses, we will see a push of warm air advection between the 925 mb and 850 mb levels which may lead to a very brief transition to freezing rain before changing over to rain. Snowfall looks less likely to accumulate across Vermont given the timing of the precip occurring after sunrise. Temperatures at the surface may hover within a degree or two of freezing as precipitation starts but would quickly changeover to rain with the only accumulations in Vermont likely above 1500 ft. Even the higher terrain will transition to rain by mid-afternoon. When all is said and done, a dusting to an inch of snow will be common across northern New York with little to no accumulation across Vermont. Rainfall totals will be pretty decent given the strong dynamical forcing with anywhere from a quarter to a half of an inch likely. Temperatures will be a little tricky on Monday as rainfall and thick cloud cover will inhibit much diurnal heating but a strong push of warm air advection should allow our temps to rise into the mid 40s by late afternoon. Rainfall will slowly taper off Monday night with another quick shot of snow possible if temperatures can cool quick enough. This time, no accumulating snowfall is expected as the duration of any snow would be short and the intensity light. The remainder of the upcoming week continues to look unsettled with a series of disturbances tracking across the northeastern US. Each model run varies from the last given that shortwaves are very difficult to time and track in the extended period. Basically, periods of showers (both rain and snow) look possible through next week as we see temperatures remain around 10 degrees below normal. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Through 00Z Sunday...Currently VFR conditions across the forecast area, except KMPV where marine stratus continues to linger east of the Green Mountains. This has resulted in mostly MVFR cigs at KMPV, though clouds may occasionally scatter out to VFR during the next couple of hours before trending back down to MVFR. Elsewhere, VFR conditions are expected to persist until about 09z. At which time, a cold front will pass from west to east, bringing scattered rain showers and area wide MVFR to IFR cigs until 18z. Thereafter, a return to VFR conditions are expected except at KSLK where lingering low level moisture will keep MVFR cigs in place. Southerly winds are expected to increase within the next couple of hours, gusting up to 20-25 kts at KBTV, KRUT, KMSS, and KSLK in advance of the approaching cold front. Gusts will end at these locations after 12z. In addition, between 03-12z, LLWS is expected as a SSW low level jet moves overhead. Outlook... Saturday Night: VFR. NO SIG WX. Sunday: VFR. NO SIG WX. Sunday Night: VFR. Chance SN. Monday: Mainly MVFR, with local IFR possible. Definite RA. Monday Night: MVFR/IFR conditions possible. Chance SHRA, Chance SHSN. Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA, Slight chance SHSN. Wednesday: Mainly VFR, with areas MVFR possible. Slight chance SHRA, Slight chance SHSN. && .MARINE... A Lake Wind Advisory continues for southerly winds with gusts 15 to 25 knots today on the Lake. Gusts will increase this evening through tonight to around 30 knots, peaking in the early morning hours. Waves will be 1-3 feet today, building to 3 to 5 feet tonight after midnight. Winds will begin to diminish around sunrise Saturday morning. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Duell NEAR TERM...Duell/Taber SHORT TERM...Clay LONG TERM...Clay AVIATION...Duell/Hammond MARINE...Team BTV

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