936 FXUS61 KBTV 172320 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 620 PM EST Mon Feb 17 2020 .SYNOPSIS... Clouds will quickly develop after midnight tonight as our next storm system impacts our region on Tuesday. This will produce a period of snow on Tuesday, along with breezy to localized gusty winds. Snowfall will generally be in the 1 to 3 inch range with isolated amounts of 4 to 5 inches possible in the High Peaks and mountains of Vermont. A wind advisory has been issued for portions of the northern Adirondacks and northern Champlain Valley for localized gusts up to 50 mph possible on Tuesday, elsewhere winds will range in the 30 to 40 mph range. Temperatures will cool this evening, but warm toward morning withs on Tuesday well into the 30s most areas, before dropping back into seasonable levels for midweek. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 600 PM EST Monday...Few changes were made to the going forecast. Currently, skies are clear across the forecast area and temperatures are expected to drop fairly quick under optimal radiational cooling conditions. However, satellite trends indicate clouds are moving in from the west a bit faster, which will inhibit said cooling. Thus, I have bumped the overnight low temperatures up by a few degrees; still, a chilly night is in store with lows in the teens for the Champlain Valley and southern Vermont, single digits across northern New York, and near or below zero for the Northeast Kingdom of Vermont. The onset of precipitation for tomorrow is still on track, beginning around 12z in northern New York and then spreading eastward. Previous Discussion... Wind advisory has been issued for portions of the northern Adirondacks and northern Champlain Valley from 12z to 03z Tues for localized gusts up to 50 mph. Water vapor is unimpressive this aftn with a very flat and fast 120 to 140 knot east to west orientation jet at 250mb acrs the central conus. In addition, limited mid level moisture is present, as westerly jet over the southern conus is minimizing sub-tropical moisture advection from Gulf of Mexico into the system. Low pres will organize over the central Plains tonight and race northeast acrs the central Great Lakes and toward Hudson Bay by Tuesday, while 1035mb modified arctic high pres shifts into northern Maine. The collision btwn cold arctic air and developing warm pacific air will produce a period of favorable 850 to 700mb fgen lift on Tuesday, resulting in a band of light to occasional moderate snow. The axis of favorable 850 to 500mb rh is narrow, as well defined dry slot develops and best forcing lifts east of our cwa by 21z Tues, resulting in a 2 to 4 hour window of accumulating snowfall from west to east. Heaviest snowfall occurs btwn 12z-20z acrs our cwa, with amounts generally in the 1 to 3 inch range with isolated 4 to 5 inches possible High Peaks/Green Mountains of VT. Precip ends by 21z as a period of drizzle/freezing drizzle but any qpf will be very light as depth of moisture and forcing is limited, with soundings showing rapid drying in all levels by 03z Weds. A very light glaze possible mainly above 1500 feet, where slightly better moisture is located. In addition, extremely fast flow aloft and developing 925mb winds of 45 to 55 knots and 850mb winds of 60 to 75 knots will lift precip quickly from southwest to northeast acrs our cwa on Tues, and create trrn focused pop/qpf fields based on strong llvl winds. Speaking of winds, have issued wind advisory for northern dacks and northern cpv for localized gusts up to 50 mph. BTV4km sounding data at Malone shows bottom of mixed layer of 40 to 42 knots, with top values of 50 to 52 knots, supporting gusts up to 50 mph or so. In addition, have examined sounding data near Alburgh and see the potential for gusts in the 45 to 50 mph, which may cause isolated power outages. South/southeast direction is climo, so no anticipating too many issues. Western slopes are tricky, as sfc to 925mb winds seem just a bit too much from the south and top of the mixed layer is in the 35 to 40 knot range, not quite strong enough, but localized gusts to 40 to 45 mph looks possible. On tues evening mixing increases behind boundary, but 850mb winds are around 50 knots, supporting gusts in the 35 to 40 mph range over the SLV and northern Dacks. Temps will be on a roller coaster ride the next 24 to 36 hrs with a chilly night tonight, followed by a mild day on Tues and another mild night on Tues. Lows tonight with clear skies/light winds and sfc dwpts in the single digits above/below 0F, range from -5F NEK/SLK to 10/15F CPV/SLV. On Tues strong llvl jet advects 850mb temps near 0c, while 925mb values range from -2C NEK to +3C SLV, supporting highs lower 30s to near 40F. Temps with clouds and winds hold in the upper teens to mid 20s. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 318 PM EST Monday...Only small changes made to short-term forecast. A secondary frontal boundary will push across the North Country Wednesday morning and will bring with it the chance for scattered snow showers across our northern zones. Snow squall parameter shows instability (40-90 J/kg) along with a narrow axis of f-gen situated along the International Border. Given lack of robust convergence and moisture thinking that any snow that does develop on the leading edge of this front will be a somewhat disorganized snow band(s), with a few heavier areas of snow embedded. Best chances for this snow will be near the International Border -- Massena-Malone- Allburgh-Jay Peak. Chances for some light snow with minimal accumulations are possible into the northern Adirondacks, northern Champlain Valley and northern Green mountains including the NEK. While not expecting any significant accumulations, a quick half inch to one inch of snow is possible along with sharply reduced visibilities. These snows may impact the morning commute on Wednesday. Winds will remain breezy on Wednesday behind this frontal passage with NW winds around 10-15 mph with gusts upwards of 25 mph during the afternoon areas. As cold pool moves in aloft the potential exists for some scattered convective snow showers, however available instability varies greatly between NAM/GFS. Sounding profiles off NAM guidance are definitely the most bullish with a dry-adiabatic sounding to the top of the mixed layer (upwards of 8000ft)...GFS much more tempered with very dry sounding (no CAPE) and mixed layer only extending to around 5000ft). Have included a mention for slight chance of snow showers during the day on Wednesday but given lack of moisture, PWATS drop to less than 0.25" therefore thinking any snow that does fly will be minimal. Temperatures Wednesday should be non-diurnal with highs occurring in the morning hours before dropping by mid afternoon behind this front into the low to mid 20s. 925mb temperatures drop to around -20C by 12z therefore expecting a pretty cold night with lows once again in the single digits above and below zero. Winds abate slightly overnight but still remain out of the NW between 5-10 mph. Wind chills as low as -15F are possible in the NEK and northern Adirondacks Wednesday night. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 318 PM EST Monday...The extended remains relatively quiet with high pressure generally in control through the entire period. NW flow will be in place aloft Thursday with below normal temperatures expected as highs will be in the upper single digits to low teens north and mid teens/20s south. Winds will continue to be somewhat brisk which will make temps feel like they're in the single digits above and below zero. Temperatures Thursday night will be chilly as well, but shouldn't completely tank (single digits above and below zero again) as gradient flow increases once again across the North Country as low pressure brushes by to the north of us. A very weak attended "front" may pass through Friday morning but should only bring an increase in clouds. Temperatures will warm but still be below normal in the low to mid 20s. As we head into the weekend, temperatures should warm a couple degrees each day with highs returning above normal in the mid to upper 30s. A few impulses will pass through zonal flow aloft but not looking at any real precipitation. With high pressure situated to our south-southwest and several lows passing to our north the remainder of the week/weekend look breezy with relatively persistent gradient flow across New England. && .AVIATION /23Z MONDAY THROUGH SATURDAY/... Through 18Z Tuesday...High pres with clear skies and light northwest winds prevails thru 06z with vfr conditions. Low pres tracking across the central Great Lakes will produce a period of snow showers and ifr/lifr conditions on Tuesday from roughly 12z to 18z across all our taf sites. Expecting cigs to lower to mvfr conditions during this timeframe, with potential vfr cigs at Rutland due to downslope se winds. In addition, strong llvl jet at 3500 to 5000 ft of 65 to 80 knots will lift acrs our taf sites on Tues, resulting in areas of moderate to severe turbulence and shear, especially near the higher trrn toward 18z on Tues. Outlook... Tuesday Night: Mainly VFR, with areas MVFR possible. Chance FZDZ, Slight chance DZ, Slight chance SHSN. Wednesday: VFR. Slight chance SHSN. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Wind Advisory from 7 AM to 10 PM EST Tuesday for VTZ001. NY...Wind Advisory from 7 AM to 10 PM EST Tuesday for NYZ027-028- 030-031. && $$ SYNOPSIS...Taber NEAR TERM...Hammond/Taber SHORT TERM...LaRocca LONG TERM...LaRocca AVIATION...Taber