Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 182253 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 653 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 643 PM EDT Monday...The locals like to call this pattern bread n butter, where conditions are favorable for upslope accumulating snow showers every 6 to 12 hours, and produce free refills daily. Crnt radar is showing the areal coverage of mtn snow showers and mix rain/snow in the valleys increasing this evening associated with a sfc cold frnt and weak embedded s/w. As flow continues to shift back to the west/northwest in the 925mb to 850mb layer, expect upslope snow showers to prevail most of the night acrs the northern Dacks and central/northern Greens. A sharp and highly elevational snowfall gradient is anticipated from a dusting to an inch possible valleys to 2 to 6 inches mtns by morning. Temps have cooled quicker than expected acrs the SLV this evening, so have made the hrly temp adjustment and added more snow than rain. Otherwise, precip type should be mostly snow at all levels by 02z this evening, which is covered in fcst. No additional changes made attm. 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 /00Z TUESDAY THROUGH SATURDAY/... Through 18Z Tuesday...Outside of a burst of snow this morning, snowfall has generally been light throughout the day. Most locations seeing snow are reporting 3-4 SM vsby with ceilings in the 1500 to 2500 ft range with VFR conditions outside of snow showers. This trend is expected to continue into the evening hours before ceilings drop below 3000 ft at most terminals. Snow showers this evening could pick up in intensity and produce brief IFR vsby at KEFK, KSLK and KBTV but these should be directly tied to snow showers with quick improvement after they pass. Winds will remain gusty from the west/northwest at 15 to 25 knots through 23Z with winds weakening to less than 10 knots overnight. Winds will again become gusty after 15Z Tuesday. 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. Slight chance SHSN. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. Friday Night: VFR. Slight chance SHSN. Saturday: Mainly MVFR, with local VFR possible. Slight chance SHRA, Slight chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Chai NEAR TERM...Clay/Taber SHORT TERM...Chai LONG TERM...Chai AVIATION...Clay

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