Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 190207 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1007 PM EDT Mon Mar 18 2024 .SYNOPSIS... Periods of snow showers, mixed with rain in the valleys are expected through mid week. Best chance of over 4 inches accumulation will be over 1000 feet elevation as well as topographically favored upslope locations of the Green Mountains and the Adirondacks. Only minor accumulations are expected in the Champlain and Saint Lawrence valleys. A strong cold front overnight Wednesday will lead to below normal temperatures on Thursday and Friday. Unsettled weather may return for the weekend, but forecast confidence is very low at this time. && .NEAR TERM /THROUGH TUESDAY NIGHT/...
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As of 1004 PM EDT Monday...Minor changes needed with late evening update, but overall fcst remains in good shape. Radar shows intervals of upslope snow showers continuing acrs northern Dacks into parts of the central/northern Greens. Based on upstream radar and water vapor trends, feel areal coverage of precip wl decrease aft 06z as weak ridging develops. The pop/qpf and snowfall have this covered well. Temps are a bit tricky this evening with northern NY running a few degrees cooler, while VT is a few degrees warmer as winds have been slow to shift to the west/northwest, especially central/southern CPV. Did make some minor tweaks to hrly temps, but overall fcst remains in good shape. Previous discussion below: The one word to describe the weather through Tuesday night is unsettled. Current mesoanalysis shows up to 200 J/kg of CAPE which doesn`t sound like a lot but it`s enough to help support snow showers across the region. The cause for this instability is a pocket of cold air aloft that continues to get colder as cold air advects southward. This should drive a period of snow showers into this evening and overnight period. With prevailing west to northwest winds, which could be gusty up to 30 mph at times, good upslope flow is expected on the windward side of the Adirondack and especially the western slopes of the Green Mountains. Snow is going to be very elevationally dependent meaning those in low elevations will likely see little to no snow through Tuesday while locations above 1000, 2000, and 3000 ft could see more and more snow the further up you go. For example, we currently have an inch or less in the forecast for much of the Champlain and St. Lawrence Valleys but have 8-12 inches in the forecast for Jay Peak and Mount Mansfield. This will be great for those who enjoy spring skiing and a nice bonus for an overall lackluster winter for much of the North Country.
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of Monday 3 PM EDT...A potent piece of northern stream shortwave energy will trigger another round of convective snow showers and even a few embedded snow squalls. Snowfall accumulations look to be topographically driven and elevation dependent. Strong cold air advection will result in lapse rates of over 8.5C/km up to 800mb as well as 50-100 J/kg of surface based CAPE. Indeed, the SLU snow squall parameter is non-zero, with somewhat higher amounts across the Adirondacks and Northeast Kingdom. In addition, it would also be a breezy to even blustery day on Wednesday, with west winds gusting over 25-30 mph at times. During the day on Wednesday, most of the accumulations should be confined to the terrain mainly above 1000 ft elevation as 925mb temperatures remain in the 0 to -2C range. So expect minimal accumulation, with the best chance for a quick coating of roadways during a heavier snow shower or embedded squall in the valley locales. It would be a different story, however, across the typically favored upslope areas of the Adirondacks and spine of the Greens, where upwards of 4 inches could accumulate. High temperatures top out in the low to mid 40s across the valleys and mid to upper 30s across the higher terrain. It does get more interesting overnight Wednesday as cold air advection continues. 925mb temperatures fall sharply into the -7 to - 10C range, allowing it cold enough for snow to accumulate even down to the valley. However, the jet dynamics remain northern stream dominated, with minimal southern stream connection. The result is continued bouts of convective snow showers overnight Wednesday. A feature that bears watching is the 700mb low potentially closing off, which would lead to more impressive widespread snowfall amounts of over 4 inches rather than being orographically driven. However, the current suite of global deterministic guidance shows the low closing to our east, which would favor the best snow across Maine. And if we were to examine ensemble guidance, there remains little to no indication that the upper low will actually close off, so the most likely solution remains a terrain dependent snowfall event, with minor accumulations across the valleys. If the upper low does close off as some deterministic guidance are suggesting, then Northeast Kingdom could see higher amounts. But until more evidence presents itself, that is a low probability outcome. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of Monday 3 PM EDT...Upslope snow showers taper off during the day on Thursday. It will be an unseasonably cold day on Thursday. With 925mb temperatures -9 to -12C, highs might struggle to approach the freezing mark with the exception of the Champlain Valley and southern VT. Thursday night would be a cold one with lows in the single digits to low teens, except mid to upper teens in the Champlain Valley. Friday looks to be another day of below normal temperatures in the upper 20s to mid 30s. For reference, typical highs are in the mid 30s to low 40s. Heading into the weekend, we warm to near seasonable temperatures. There is potential for some form of unsettled weather due to the development of a coastal storm. However, there remains too much uncertainty in the storm track and consensus among model guidance to articulate any potential storm impacts at this time. Stay tuned. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Through 00Z Wednesday...Although most terminals are currently VFR, variable flight categories will be possible this evening as snow showers persist across the region making for bouncy flight categories. The best potential for IFR conditions will be at KEFK and KSLK due to more confidence in snow showers, although given the variability TEMPO groups were utilized. Outside of snow showers, a mix of VFR and MVFR ceilings will persist until around 12Z when most terminals should trend towards VFR. Winds overnight will generally be less than 10 knots and westerly, become gusty after 15Z. Outlook... Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHSN. Wednesday: Mainly VFR, with local MVFR and IFR possible. Likely SHRA, Likely SHSN. Wednesday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Thursday: VFR. Chance SHSN. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. Friday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Saturday: Mainly MVFR, with local VFR possible. Chance SHSN, Chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Chai NEAR TERM...Clay/Taber SHORT TERM...Chai LONG TERM...Chai AVIATION...Kremer

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