Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 212336 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 636 PM EST Wed Feb 21 2018 .SYNOPSIS... A surface cold front will continue to move across the North Country tonight with much cooler temperatures and breezy northwest winds. Temperatures will drop below freezing with some icy spots possible from any leftover standing water. A weak system will spread a chance of light snow across southern and central Vermont on Thursday afternoon with more mixed precipitation arriving on Friday into Saturday. && .NEAR TERM /THROUGH THURSDAY/... As of 608 PM EST Wednesday...Overall forecast in good shape with just some minor tweaks to temperature trends...slowed down the cooling by a couple of hours. And bulk of the precipitation has shifted out of the area with just some lingering scattered showers across the southern areas. Thus have lowered precipitation chances downward just a bit and blended into the dry forecast that is expected overnight. Previous Discussion... Flood watch for ice jam related flooding has been extended until 7 AM Thursday. Several rivers are approaching action stage with others reporting ice jam related flooding, especially northern NY. Water vapor shows mid/upper lvl ridge being suppressed as upper level trof and sfc cold front pushes across the ne conus. Cold air aloft quickly moving into northern NY with Whiteface summit down to 36f...which will help to decrease rate of snow melt in NY. This cold air will quickly spread into the mountains of central/northern VT in the next 1 to 2 hours. Still noticing a strong channel of deep layer moisture advecting from the Gulf of Mexico into the MS Valley in the fast west/southwest flow aloft. This active flow aloft with embedded pieces of energy and associated sfc boundary draped across the region will be the focus for several rounds of precip over the next couple of days. Tonight...sfc cold front sweeps across the region with strong low level cold air advection prevailing on 925mb to 850mb winds of 30 to 40 knots. 850mb temp profiles show a sharp nw to se gradient with values between 0c near VSF to -7c at MSS...these temps cool another degree or two by 12z Thursday. Even with a 20 to 30 degree drop in temps...we will still be above normal for lows tonight...with values ranging between 18 and 28f. Given the lack of snow cover and some gradient flow...have gone several degrees above guidance. Any leftover rain showers with change to mountains snow flurries...with limited accumulation expected...due to the lack of moisture. north to south moisture gradient develops from 1042 mb high pres over southern Canada and mid level moisture streaming from southwest to northeast over the Ohio Valley into Southern New England. Models still disagree on northern placement of qpf/snowfall across our cwa...but either way anything that falls will be light. Have bumped pops to low likely across extreme rutland/windsor counties for Thursday aftn with nil values along the international border. Highs will range from the mid 20s mountains to mid 30s warmer valleys...a little closer to normal. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 316 PM EST Wednesday...Active southwest flow aloft pattern continues as next system impacts our cwa on Friday into Friday Night. Still some uncertainty on timing of precip and associated ptype...given the complex thermal profiles across our cwa. Can 1040mb sfc high pres to our north, supply enough low level cold air to support a mix of freezing rain/sleet or does the progressive 850mb southwest winds of 30 to 40 knots push warm layer north of our cwa with mainly rain? NAM is colder with boundary layer and 925 to 850mb thermal profiles and would support a snow to mix to rain type of an event with freezing rain/sleet prevailing east of the Greens/NEK. Meanwhile...GFS is much more aggressive with pushing warm nose north into our cwa...with a mix to rain event expected. Given...uncertainty have a wintry mix in grids with rain likely in the warmer valley locations. The details can be worked out as we approach this event...initial thoughts would be an advisory maybe needed for eastern/central VT and parts of nny. Once again qpf will be light and any ice accumulation system is very progress in the fast flow aloft. Temps warm into the upper 30s/lower 40s cpv and western dacks with lower/mid 30s east of the greens/northern SLV. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 257 PM EST Wednesday...A deep subtropical high over Florida will lead to a persistent and mild WSW flow aloft through the long term period. High pressure over the east will lead to a rather mild day on Saturday with highs in the 40s before the next round of precipitation moves in later in the evening. A strong low pressure moving out from CO through the western Great Lakes early Sunday morning before finally moving into James Bay Canada Sunday night. The associated occluded frontal system and precipitation will move through the North Country late Saturday into Sunday. While we`ll be on the warm side of that system, with the arrival overnight and below freezing temps across area at that time, we can expect a wintry mix, especially across northern NY, of snow/sleet and freezing rain. By mid morning, temps bounce back above freezing, changing precipitation over to rain, though NEK could hold on to a mix until later in the day Sun. The winds should be stronger on Sunday as we see some downsloping developing. Anticipate 20-25kts with gusts of 25-35kts along the western slopes of the Greens and the northern slopes of the Adirondacks, though a wind advisory isn`t of the question for part of the day Sunday. Looking into next week, things look a little drier and slightly cooler Monday and Tuesday with ridging aloft and a NW flow, but highs will still be above seasonal normals, upper 30s to lower 40s with lows overnight in the mostly in the mid 20s to low 30s. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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Through 00Z Friday...Expect MVFR/VFR ceilings through about 04z then VFR ceilings are expected for the remainder of the period. Visibilities will be in the VFR category through the entire period. Winds will be gusty from the northwest through about 04z...then taper off under 10 knots for the remainder of the period. Outlook... Thursday Night: VFR. Slight chance SHSN. Friday: Mainly VFR, with local MVFR possible. Likely RA, Chance SN. Friday Night: Mainly MVFR, with local IFR possible. Chance RA, Chance FZRA, Chance PL. Saturday: Mainly MVFR, with areas VFR possible. Slight chance SHRA, Slight chance SHSN. Saturday Night: VFR. Chance SN. Sunday: Mainly MVFR and IFR, with local VFR possible. Definite RA, Definite SN. Sunday Night: Mainly VFR, with local IFR possible. Chance SHRA, Chance SHSN. Monday: VFR. Slight chance SHRA, Slight chance SHSN.
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&& .HYDROLOGY... As of 330 PM EST Wednesday...Flood watch has been extended until 7 AM Thursday for the entire North Country. Rivers continue to rise this evening from significant snow melt at the mid/upper level elevations. The good news temperatures are quickly cooling aloft which will greatly reduce snow melt runoff tonight. Still expecting localized ice jam related flooding overnight, especially on rivers where ice jams remain in place from the mid January thaw. These river include but are not limited to the following: The Little Salmon, St Regis, Saranac, Great Chazy, Ausable, Lamoille, Missisquoi, Winooski, and Passumpsic. && .CLIMATE... A RECORD HIGH TEMPERATURE OF 70 DEGREES WAS SET AT MONTPELIER VT TODAY. THIS BREAKS THE OLD RECORD OF 57 SET IN 1953. THIS ALSO BREAKS THE ALL TIME MONTHLY FEBRUARY RECORD OF 63 SET BACK ON FEBRUARY 23RD OF 2017. A RECORD HIGH TEMPERATURE OF 69 DEGREES WAS SET AT BURLINGTON VT TODAY. THIS BREAKS THE OLD RECORD OF 59 SET IN 1981. A RECORD HIGH TEMPERATURE OF 63 DEGREES WAS SET AT MASSENA NY TODAY. THIS BREAKS THE OLD RECORD OF 62 SET IN 1953. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Flood Watch through Thursday morning for VTZ001>012-016>019. NY...Flood Watch through Thursday morning for NYZ026>031-034-035- 087. && $$ SYNOPSIS...Taber NEAR TERM...Evenson/Taber SHORT TERM...Taber LONG TERM...Verasamy AVIATION...Evenson/Verasamy HYDROLOGY...TABER CLIMATE...TEAM BTV is the U.S. government's official web portal to all federal, state and local government web resources and services.