Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 261322 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 922 AM EDT Tue Mar 26 2024 .SYNOPSIS... Ahead of a weak frontal passage mild temperatures are expected today, and areas of drizzle tonight with scattered rain showers following for Wednesday. Mild temperatures continue for the remainder of the week with additional chances for showers Thursday, possibly ending as a light coating of snow. Cool and dry weather is expected for the upcoming weekend. && .NEAR TERM /THROUGH WEDNESDAY/...
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As of 918 AM EDT Tuesday...Have further increased cloud cover in today`s forecast given satellite trends. Mid/upper-level clouds spreading in from the west ahead of a frontal boundary draped over the Ohio River Valley. Meanwhile from the east, low clouds continue to push in from the east amid onshore flow regime. Temperatures in Burlington quickly warmed to 40 over the last hour, but rate of additional temperature rise will be tempered as low clouds fill in. Given the evolving cloud cover coupled with warm air advection from the west/southwest, temperature forecast remains the trickiest part of today`s forecast. Previous Discussion...Outside of some light patchy drizzle across the southern mountains, today`s forecast features increasing clouds and mild temperatures ahead of a frontal passage tonight. Increasing southeasterly flow will filter in low clouds across eastern Vermont this morning, while mid/high clouds approach western/northern areas from the west. A sharp gradient in temperatures is expected with low clouds keeping temperatures in the 40s east of the Green Mountain spine, while westward, 925mb temps rising to +8-10C will support highs well into the 50s with some low 60s possible in the St. Lawrence Valley. For tonight, chances for showers increases especially across northern New York as low pressure tracking well west of the region through the central Great Lakes will advance an occluded front toward the region. Additional chances for showers follow for Wednesday across the entire region as the front stalls to our west and several waves of upper level energy ride ahead of the boundary through the forecast area. Precipitation should be scattered in nature, with limited QPF expected. A mild night is expected tonight west of the Green Mountains with lows mainly in the 40s, while eastward cooler temps will remain with lows in the 30s supporting the idea of the potential for some patchy freezing drizzle. Warmer temps eventually develop across the entire region Wednesday afternoon with widespread highs in the upper 40s to lower 60s. It should be noted that with a deep snowpack across the region and warm air moving over said snowpack, there could be areas of fog tonight through Wednesday where winds decouple. Confidence is low right now as dewpoints remain in question, so have left out of the forecast for now.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 414 AM EDT Tuesday...On Wednesday night, a decaying cold front will shift east into northern New York. There`s some question on whether it washes out entirely before reaching out area or not. If it does make it, there should be a few showers along the boundary. If it does not make it, it is hard to say because there`s even question on whether there is still some positive thickness advection across eastern Vermont. I suppose this would define the airmass as "junky" with spotty showers streaming northeast along the thermal gradient that remains along the washed up front. Lingering warm air means temperatures will likely remain above freezing ranging in the mid 30s to lower 40s. During the day, an embedded shortwave within the longwave troughing across the eastern CONUS, in conjunction with some convective activity along the coastline, will send a surge of moisture northward. Where that thermal gradient is will play a large part in whether it crosses here. Forecast guidance is split between dry or very wet, with only a few middle ground solutions in some ensembles. What we`ll have to watch is another embedded shortwave a bit closer to the upper low that digs southeast about the same time, which will advect dry air into the region. This will result in a very sharp precipitation/PoP gradient. If the northern stream system is progressive, most precipitation should remain well east. There`s quite a bit of spread with this. The forecast employs a technique often used this cold season with these high uncertainty events. It`s a blend of blends, and future updates will follow statistical trends where it needs to be taken. High temperatures in the 40s should support snowmelt across the region as well. If there`s a westward shift with the moisture plume, then we`ll have to keep a close watch on how much liquid is getting into our rivers. Some probabilistic guidance indicates sharp rises, potentially near minor flooding at Otter Creek at Center Rutland and the Mad River at Moretown. Overnight, the system appears most likely to head off shore. Again, there remains a few uncertainties. The main one being whether there is any level of phasing between the two systems. If they do interact, then precipitation will be slower to shift east, and with cold air and falling heights, a transition to snow would then take place sometime near or after sunset. This possibility would mainly be confined to eastern Vermont based on present information. Temperatures overnight will sink into the 20s to lower 30s, Thursday night. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 414 AM EDT Tuesday...On Friday, we`ll be in the subsidence side behind the offshore system that will have developed into a deep, stacked low. Cool northwest winds will result in temperatures relatively close to seasonal normals, which are mid 40s and overnight lows in the 20s. A shortwave blitzes east in zonal, channeled flow aloft on Sunday. The placement of it is widely variable at this stage, but if it comes through overnight, it could support some snow. If it comes through in the day, then it`d be elevation dependent rain and snow. By next Monday, conditions appear likely to favor dry conditions, with temperatures trending back upwards. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... Through 12Z Wednesday...MVFR ceiling are quickly advancing through central/southern Vermont and the expectation for the remainder of the day is that this northward advancement will continue reaching KMPV within the next 2 hours, KEFK/KBTV/KPBG by 19-21Z, and eventually KSLK/KMSS by 22-02Z. Further lowering of ceiling is expected after 00Z with most sites IFR by 06Z. Winds will generally be <8kts from the SE except locally NE at KMSS through much of the period, with areas of LLWS after 06Z. Outlook... Wednesday: Mainly VFR, with local IFR possible. Chance SHRA. Wednesday Night: MVFR/IFR conditions possible. Chance SHRA. Thursday: MVFR/IFR conditions possible. Chance SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. Friday: VFR. Slight chance SHRA. Friday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Saturday: Mainly VFR, with areas MVFR possible. Slight chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff SHORT TERM...Haynes LONG TERM...Haynes AVIATION...Lahiff

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