Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 241114 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 714 AM EDT Sat Mar 24 2018 .SYNOPSIS... A trough of low pressure aloft will prevail across the North Country this weekend with below normal temperatures and a few scattered snow shower expected. Given the lack of moisture any snowfall will be light and under an inch. Temperatures will be mainly in the 30s today, but warm into the 40s to lower 50s by Tuesday with increasing amounts of sunshine. Our next weather maker impacts our region with rain showers Wednesday into Thursday with temperatures in the mid 40s to lower 50s. && .NEAR TERM /THROUGH SUNDAY/...
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As of 708 AM EDT Saturday...Updated to capture latest satl trends and integrate into the sky grids...which shows a window of clear skies over northern ny, before additional clouds develop by 15z. Also, have sharpen elevation temp gradient as Whiteface currently 12F...indicating the cold air advection occurring around 850mb. Thinking with intervals of clouds/sun and northerly winds...temps will only rise several degrees at most today. All covered well in crnt forecast. Water vapor shows mid/upper level trof across the ne conus with our next short wave energy several hundred miles north of the international border. Based on water vapor presentation, this system has very limited moisture, but strong dynamics. The core of the coldest 850mb to 500mb temps will pass to our west overnight...while northerly winds prevail from the sfc thru 850mb. GFS/ECMWF and NAM 850mb to 500mb rh progs continue to show deeper moisture advecting from ne to sw across our cwa btwn 03z-09z tonight...which combined with energy aloft will produce some very light snow showers. Once again pws are <0.25" so any qpf/snowfall will be light and generally under 1.0" The best combination of lift/moisture will be northern Dacks/northern Greens, including the NEK, where I will mention high chc pops overnight. Temps will continue to be challenging, especially with periods of clouds and general low level cold air advection today into tonight. Progged 925mb to 850mb thermal profiles fall 1 to 3 degrees today under northerly flow...with values btwn -8c and -15c by 18z. Expecting steady or slowly falling temps today with mid 30s valleys with maybe a few readings near 40f lower CT River Valley and upper teens summits. Lows tonight will be highly driven by the areal coverage of clouds...which should thin aft 09z, especially slv/western dacks. I have lows from 10f to l/m 20s cpv/lower ct river valley. If more clearing develops, these values will be way too warm, especially with continued snow pack and low level thermal profiles. Sunday...will feature increasing amounts of sunshine with brisk north winds. Progged 850mb temps hover around -10c, with good mixing support upper teens summits to mid/upper 30s warmest valleys. Building ridge aloft and associated subsidence will help in development of mostly sunny skies, except central/eastern vt where some mid level moisture/clouds will linger.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 403 AM EDT Saturday...Sunday night will be colder as a ridge builds over the East Coast. At the surface, a strengthening high over southern Quebec will usher in colder, drier air from the northeast that will allow 850 mb temps to once again drop below -10C over the forecast area. This will set the stage for a night of fairly strong radiational cooling under clear skies and light winds. Temperatures over valleys will drop into the teens overnight and into the single digits in the northern Adirondacks and Northeast Kingdom. Monday will start off crisp and chilly. During the day however, expect temperatures to rebound and supply a fairly pleasant March day. The surface high will shift eastward to the Canadian Maritimes, putting the forecast area in the region of warmer, southerly/southwesterly return flow behind the high by late afternoon. The combination of warm air advection (850 mb temps progged to warm 5+ degrees during the daytime hours), and the strong March sun will allow daytime temperatures to climb to back into the upper 30s/low 40s. Monday night, warm air advection will continue under return flow. Despite the warming air mass, clear skies overnight will allow surface temperatures to drop to the teens/20s in the valleys and once again into the single digits in the northern Adirondacks and Northeast Kingdom. This should be the last night of the week with below average lows however, as Tuesday during the day we`ll see a pattern change with noticeably warmer weather commencing. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 403 AM EDT Saturday...High clouds will start to move in from southwest to northeast Tuesday morning as southwesterly warm air advection/moisture advection kicks into full gear. By this time, the aforementioned high pressure will have retreated to the east coast of Canada, drawing behind it a long, fetch of deep southwesterly flow extending from the Gulf Coast through New England. Meanwhile, further west, a trough will dig over the Rockies and into the central US, further reinforcing the southwesterly fetch downstream. In terms of sensible weather, this will bring us increasing coverage and thickening of clouds starting Tuesday along with daytime high temperatures that will top out near 50 Tuesday and only fall into the upper 20s/low 30s Tuesday night. By Wednesday morning, increasing isentropic ascent over the area as a warm front pushes northeastward will support some precipitation. Model progged precipitable water values of 0.75+ inch Wednesday indicate plenty of moisture available, however deep southwesterly flow will lead to highly variable coverage of precipitation controlled by terrain. The Saint Lawrence Valley and the western Adirondacks will see some measurable rain Wednesday out of this setup, however the majority of areas further east will be mainly downsloped with just some isolated showers sneaking in. This precipitation will mainly be in the form of rain, however higher terrain could see some snow or a rain/mix during the nighttime hours. Wednesday night, the pattern will temporarily become more zonal. This will act to cut off our better moisture feed from the southwest, resulting in a brief dry spell in the weather. The chance of precipitation then quickly returns Thursday night however as both northern and southern stream shortwave energy act to deepen the upstream trough over the central US. Daytime highs both Wednesday and Thursday will once again top out around 50 in many locations, a good 5-10 degrees above normal for late March. Looking further ahead into the early weekend, precipitation chances continue as the upstream upper level trough continues to send impulses through New England. As far as temperatures go, Saturday looks to be the end of this week`s warmup thanks to colder, northwesterly flow resuming after the trough axis finally pushes through. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
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Through 12Z Sunday...VFR conditions prevail today with perhaps some mvfr cigs at slk/mpv and btv overnight. The combination of increasing moisture and short wave energy will help to lower cigs by tonight...with a brief period of light snow possible at slk/mpv. Have utilized tempo group to place 4sm -shsn at slk. Otherwise...sfc analysis shows northerly gradient between high pres over the northern Great Lakes and departing low pres over northern Maine...supporting some localized gusts btwn 15 and 20 knots today. Any leftover snow shower activity and mvfr cigs will quickly improve by Sunday across our taf sites. Outlook... Sunday: VFR. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. Slight chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...RSD LONG TERM...RSD AVIATION...Taber is the U.S. government's official web portal to all federal, state and local government web resources and services.