Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 160530 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 130 AM EDT Fri Mar 16 2018 .SYNOPSIS... Snow showers will become confined mainly the higher elevations tonight into Friday with only light additional snow accumulation. Fair and seasonably cold weather returns by this weekend into Monday of next week as Canadian high pressure settles across the area. Low pressure may bring a returned chance of snow by the middle of next week, but current indications suggest higher impacts from this system will remain largely south of our area. && .NEAR TERM /UNTIL 2 PM THIS AFTERNOON/... As of 1038 PM EDT Thursday...Only minor adjustments to temperatures and winds with this update. The main focus will continue to be snow showers - primarily over the mountains - as the region remains under northwest flow with upslope conditions into the northern Adirondacks and northern Green Mtns. Have seen some brief periods of flurries at BTV this evening, but any additional light accumulations should be confined to the immediate western slopes of the Greens, and the higher summits of the Greens/Adirondacks overnight. The upper low currently spinning over eastern New Brunswick will push toward the Canadian Maritimes tonight and Friday while an upper shortwave rotating around the back of the departing low digs toward the region. The favored upslope areas of the mountains will continue to see light snow through Friday afternoon with another 1 to 3 inches of snow accumulating in the higher elevations. There could be some slight increase in precipitation coverage this evening as a weak boundary crosses the North Country, but overall expect a downward trend through Friday as the upper low pulls away. Winds will surge aloft as we see cold air advection behind this weak boundary, and expect these will mix down to the surface on Friday. Temperatures on Friday will only be in the lower/mid 20s in the mountains and the mid/upper 20s in the valleys, and wind gusts of 20-30 mph will make for a brisk day. Snow showers will wind down Friday evening with the loss of daytime heating and upper support, but precipitation chances will increase late Friday night ahead of a stronger frontal passage. Friday night`s lows will be quite chilly, ranging from around 10 in the northern mountains to the upper teens in the wider valleys. && .SHORT TERM /2 PM THIS AFTERNOON THROUGH SATURDAY NIGHT/... As of 315 PM EDT Thursday...Mid/upper level trof prevails with much below normal temps anticipated. Interesting setup for Saturday with regards to modified arctic boundary and associated potent 5h short wave energy dropping south across our cwa and potential for snow showers with isolated snow squalls. Utilizing the local developed snow squall parameter shows the best combination of instability/moisture and lift across our central/northern cwa btwn 12z-16z Saturday...before front drops to our south...along with better moisture. Thinking scattered snow showers develop along the boundary with a few embedded snow squalls...but coverage will be limited by available moisture. A quick inch or two is possible in the heavier convective elements...especially northern Greens into the NEK on Saturday morning...where the best 925mb fgen forcing and sfc based instability is located. Elsewhere...scattered snow showers with a quick dusting possible...but moisture will limit areal coverage of activity...along with quick movement of boundary. Moderate low level cold air advection develops as progged 850mb temps drop to near -20c by 18z, on brisk northwest winds of 25 to 35 knots. These temps/winds will produce mid winter conditions on the summits with highs only in the single digits on Saturday with much colder wind chill values. Highs in the valleys mainly upper teens to mid 20s with lows -10f to +5f. The combination of clearing skies, lighter winds...and fresh snow pack will allow temps to quickly drop on Saturday Night. Would not be surprised a few readings near -15f in the colder valleys across northern ny given the position of 1020mb high pres. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 315 PM EDT Thursday...Northwest 700 to 500mb flow continues with below normal temps and mainly dry conditions for Sunday and Monday. Several embedded 5h vorts in the flow aloft will have very limited moisture to work not expecting much precip...maybe a few scattered mountain driven snow showers during the afternoon hours. 1030mb high pres axis from Hudson Bay to Mid Atlantic along with deep dry layer will produce mostly sunny skies with cool temps. Progged 850mb temps warm 2 to 4 degrees on Sunday with values -14c and -18c...supporting single digits to lower teens mountains to upper teens to mid 20s warmer valleys. Expect large differences between valley floors and mountains summits for Sunday and Monday in terms of temps. Once again...overnight lows will be tricky and highly depend upon winds/sky cover...but expecting values mainly below zero deeper/protected valleys to lower teens cpv/slv. Next large scale mid/upper level trof and multiple energy pieces in a complex pattern approaches the eastern conus late Tues thru Thursday. As we have seen the past 3 storms...models have struggled handling timing and magnitude of s/w energy...along with amount of phasing between the northern and southern streams. The upper atmosphere is extremely complex by mid week with split flow developing over the central conus and some upstream blocking over the northern Atlantic prevailing, while a trof deepens over the eastern conus. Guidance continues to show considerable spread with mid/upper level trof evolution and s/w interaction, along with cyclone development. At this time, no one solution is favored over another...and we will continue to mention chc pops in the forecast. The good news is...most guidance keeps thermal profiles cold enough for mainly snow...but lots of uncertainty on placement of qpf and amount, as well as track of surface low pres. Will continue to mention chc pops with a north/south gradient based on latest rh progs and position of surface high pres to our north. Plenty of details to be resolved in future runs and lots of time to fine tune the forecast. Temps mainly in the 20s mountains towns to mid/upper 30s valleys. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Through 06Z Saturday...A mix of VFR/MVFR through 14Z with scattered flurries and light snow showers, trending mainly VFR after 14Z with any lingering light pcpn becoming more confined to higher terrain. MVFR may linger at KSLK slightly longer. Winds west/northwesterly from 7 to 15 kts with occasional gusts to 20 kts through 12Z. Gusts increase into the 18-25 kt range after 12Z as atmospheric mixing deepens. Outlook... Saturday: VFR. Windy with gusts to 30 kt. Chance SHSN. Saturday Night: VFR. NO SIG WX. Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: Mainly MVFR, with areas VFR possible. NO SIG WX. Monday Night: Mainly MVFR, with areas VFR possible. NO SIG WX. Tuesday: Mainly MVFR, with local IFR possible. Slight chance SN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings NEAR TERM...Banacos/Hastings SHORT TERM...Taber LONG TERM...Taber AVIATION...JMG is the U.S. government's official web portal to all federal, state and local government web resources and services.