Area Forecast Discussion
Issued by NWS Burlington, VT

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760 FXUS61 KBTV 090936 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 436 AM EST Mon Dec 9 2019 .SYNOPSIS... Light wintry mixed precipitation is ongoing this morning, and we may have some light icing or snow accumulation. This mornings commute may be impacted, but temperatures warm during the day changing precipitation over to rain showers. Winds will continue to be gusty out of the South until surface cold front finally pushes through later in the day Tuesday. Drier weather returns Tuesday night through Friday night with colder than normal temperatures anticipated. Saturday will bring our next chance for rain. && .NEAR TERM /THROUGH TUESDAY/... As of 400 AM EST Monday...Strong warm air advection over our area and gusty southerly winds as well as strong low level jet have helped to push temperatures into the mid 30s to around 40, except for areas East of the Greens where temperatures remain in the upper 20s. So far this morning most observations have been rain or snow, but isolated pockets of sleet are possible. Areas east of the Greens where the temperatures have remained colder will still have some freezing rain resulting in light icing. Untreated surfaces elsewhere may take some time for the pavement temperatures to come up and a light glaze will be possible as well. Precipitation this morning will mainly impact areas of VT north of I-89. We`ll have a brief break in precipitation, then more rain moves into the area from the South around 17z across Southern VT, spreading northward all the way to the international border by about 21z. With low level jet over the area, QPF will be terrain driven with highest amounts in the southeast upslope regions of the eastern Dacks and central/southern Greens. Downslope flow will limit QPF in the Champlain Valley and parts of the Northern New York north of the Dacks. Maximum temperatures today will reach the 40s areawide, then not fall too drastically overnight with strong winds, clouds and showers continuing, mainly lower 40s. Precipitation will become more showery following 00z tonight, and eventually ending from west to east towards early Tuesday morning. Areas of fog are possible through the period with rainfall on top of snowpack, especially deeper/protected valleys. Still not expecting any significant hydrology issues, though with heaviest rain in southern Vermont and some snowmelt as well, Otter Creek at Center Rutland is forecast to rise above flood stage. With low pressure system lifting through Great Lakes and then well to our Northwest, surface cold front will finally push through our area on Tuesday. Winds will veer from Southerly to Westerly, then eventually Northwest behind the departing front. Any remaining rain showers will change over to snow showers on Tuesday, with early morning high temperatures established in the 40s then dropping through the day. Temperatures will drop a good 15 degrees or so during the day Tuesday. As midlevel dry air settles in behind the front Tuesday afternoon, chances of precipitation will be decreasing. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 345 AM EST Monday...Cold air advection will continue Tuesday night behind the aforementioned cold frontal passage. Precipitation will come to an end across much of the region as best moisture and forcing move to our south and east, with northern areas seeing some breaks in the clouds as well. However, far southern/southeastern areas may see snow showers continuing as a weak wave of low pressure traverses along the front positioned off the New England coast. This southern focus to the precip will continue Wednesday morning, but snow chances will increase, particularly over northern NY, Wednesday afternoon as winds turn to the southwest ahead of a secondary cold front moving south out of Ontario. This will lead to lake effect snow over the favored areas east of Lake Ontario, with around an inch of accumulation possible through the daylight hours. Temperatures Tuesday night are a bit tricky as they will depend on extent of cloud cover and whether locations can decouple, but regardless, it`ll be turning colder. Lows look to be in the 10 to 20 range, with southern valley locations remaining in the lower 20s. Wednesday`s temperatures will rebound a bit owing to the south- southwest winds; highs will be in the mid 20s to around 30. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 345 AM EST Monday...A secondary cold front will move across the region early Wednesday night, turning winds to the west/northwest and shunting any lingering lake effect snow south. High pressure will settle over New England Thursday, making for a dry but cold day with highs only in the teens and 20s. Thursday night will be cold as well, though radiational cooling potential might not be fully realized as the ridge axis shifts east, placing us under southwest flow and increasing cloud cover by early Friday. This continues through Friday, which will be dry but quite a bit warmer than Thursday. The weekend continues to look wet, though the exact details remain in question. The latest GFS is stronger with an upper trough swinging across the Upper Midwest and through the Great Lakes, developing surface low pressure over the Ohio River Valley and pushing it northeastward through the St Lawrence River Valley Saturday and Saturday night. Meanwhile, the ECMWF is weaker with the upper shortwave and slower and further south with the surface low, taking it over Long Island Saturday evening and into coastal Maine on Sunday. Either way, would expect precipitation to move in Friday night or Saturday. Though it may start out as a bit of snow or perhaps a wintry mix, precipitation would change over to all rain Saturday and continue into the evening, then perhaps wind down overnight before showery conditions resume on Sunday as the main upper trough moves through. Have stayed close to a model blend for this time frame given the discrepancies between model solutions. Trends will need to be monitored through this week as the event draws nearer. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... Through 06Z Tuesday...Wind shear will continue to be an issue across much of the area through about 12z Monday with a lull in the winds between 12z and 18z on Monday and then a second low level jet moving in and creating low level wind shear once again across the area from 18z to the end of the period. During both periods of low level wind shear winds will be from the south at 2000 feet at speeds in the 40 to 50 knot range. This will result in areas of moderate to severe turbulence. Otherwise looking at VFR conditions with respect to ceilings and visibilities through about 12z. After 12z ceilings will be lowering into the MVFR category and possibly into the IFR category after 20z. Visibilities will be lowering as precipitation becomes widespread after 12z. Precipitation prior to 12z will be light and may be a mix of snow, sleet, freezing rain, and rain before becoming all rain between 12z and 18z. Visibilities will lower into the MVFR category after 12z and could briefly reach the IFR category. Outlook... Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. Tuesday Night: VFR. Chance SHSN. Wednesday: VFR. Chance SHSN. Wednesday Night: VFR. Slight chance SHSN. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. && .MARINE... A period of very strong winds will impact Lake Champlain through the day. South winds of 25 to 35 knots and frequent gusts to 40 knots will occur, creating very difficult boating conditions, especially on the north end of the lake where waves of 5 to 7 feet will occur because of the strong winds. Winds will eventually taper off a bit on Monday, but remain in the 20 to 30 knot range and waves of 4 to 6 feet. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Neiles NEAR TERM...Neiles SHORT TERM...Hastings LONG TERM...Hastings AVIATION...Neiles MARINE...Evenson

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