Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 180259 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 959 PM EST Sat Feb 17 2018 .SYNOPSIS... High pressure sliding off the New England coast this afternoon is making way for a low pressure system passing south of Long Island and outside the benchmark. Light snowfall is expected across Southern Vermont and along the spine of the Greens, generally 1 to 4 inches. A significant warming trend is expected Monday through Wednesday of next week, along with increasing chances for rain. Near record high temperatures are possible Tuesday into Wednesday, with highs well into the 50s and possibly lower 60s. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 916 PM EST Saturday...Overall, forecast is on track with minor updates made to PoPs and temperature grids. While radar looks like snow has overspread the North Country, much of the leading edge is virga as precipitation is evaporated in the dry mid and low levels. However, latest observations upstream over southern Vermont/central New York show dewpoints rising quickly as deep moisture pushes in from the southwest and wet bulbing moistens the column. Areas of southwestern Vermont are already reporting snow at the surface, so given the fairly quick moistening of the column seen upstream, expect snow to start over most of Vermont by midnight. Previous Discussion...As high pressure moves away from the region this evening, a low pressure system will be skimming the New England coast to the South. Some light snow will spread into Vermont after about 11pm. Very progressive mid-level flow is in place, and will push this system east of the region pretty quickly. All snow should fall by about 8am. Snowfall totals will range from around an inch or less across Northern New York to two to five inches in Southern Vermont. There may be some higher totals along the spine of the Greens as well. Clouds and snow will keep overnight temps mild, ranging through the 20s. Another ridge of surface high pressure will build into the area Sunday and Sunday night from the South. Will take a bit to push the rest of the moisture eastwards on Sunday, but we should see some sunshine by the afternoon, especially in the Champlain valley. We may also see some upslope snow showers lingering through the morning hours in the NW facing slopes of the Greens. Temperatures will be above normal again on Sunday with some upper 30s in the Champlain and Saint Lawrence valleys with lower to mid 30s elsewhere. Gusty NW winds upwards of 20 mph at times during the afternoon. Sunday night high pressure center drifts eastward and pressure gradient will be increasing with a southerly return flow developing. Sunday night will also feature temperatures well above seasonal normals with mid 20s in the valleys and teens in the higher elevations. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 347 PM EST Saturday...High pressure will continue to exit to our east on Monday, placing the region under deep southwest flow. Hence we`ll see increasing warm advection and moisture, leading to a period of precipitation Monday and Monday night. It`ll take a bit for the dry air at the surface to saturate, so precipitation will mostly hold off until Monday afternoon, and temperatures will be above freezing in most areas by then. So expect most locations will see the precipitation start out as rain, though a bit of snow may mix in across the higher terrain of the Adirondacks and northern Greens at the onset. The rain will be steadiest overnight Monday night as a warm front lifts across the region. This will also allow temperatures to rise much of the night after a brief drop in the evening east of the Greens. Overall, 24 hour rainfall amounts will be about a quarter to a half inch, with the Champlain and Connecticut River valleys seeing the least due to shadowing in the southwest flow. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 347 PM EST Saturday...The focus for this term becomes very warm, near record warm temperatures, along with potential rainfall placement. The warm front looks to become nearly stationary north of the Saint Lawrence Valley through Wednesday morning, with waves of low pressure traveling along it. This will bring periods of rain, particularly across northern sections. There are still some model differences in frontal placement and the extent of the associated precipitation, but the consensus of the guidance shows 0.50-1.50 inches will be possible through Wednesday with the heaviest amounts along the border. In addition, temperatures will warm considerably through the period, approaching record highs on Tuesday and Wednesday. With temperatures well into the 50s to around 60, and Tuesday night`s low staying well above freezing, runoff from snowmelt and rainfall will be a concern. See the hydrology section for more details. The mild spell comes to an end later Wednesday with a cold front quickly crossing the region. Cooler and drier air will return under high pressure through Friday. However, temperatures will remain above seasonal normals, with highs remaining in the 30s to around 40 both Thursday and Friday. The threat of precipitation returns Friday night and Saturday with another surge of warmer air, though not nearly as mild as what we`ll see earlier in the week. Note that there are considerable differences in model solutions for next weekend, so have stayed close to a model blend to account for the uncertainty. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/...
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Through 00Z Monday...Ceilings will gradually lower but remain VFR through 02Z. Thereafter, will see some developing mainly light snow as low pressure passes well south of New England, and an upper level low moves across NY and central New England. Will see mainly MVFR conditions 03-12Z with periods of light snow, except 1SM light snow and IFR/LIFR expected at KRUT. Snow should exit quickly around 12Z Sunday with ceilings/vsby returning to VFR by mid-morning. May see minor impact to airport ground ops early Sunday morning at KRUT with 2-4" snowfall expected. Winds generally south 6-12kts overnight, becoming W-NW 5-10kts during the daylight hrs on Sunday. Outlook... Sunday Night: VFR. NO SIG WX. Washingtons Birthday: Mainly VFR, with local MVFR possible. Chance RA. Monday Night: Mainly MVFR, with local IFR possible. Definite RA. Tuesday: Mainly MVFR, with local IFR possible. Likely RA. Tuesday Night: Mainly MVFR, with local IFR possible. Likely RA. Wednesday: Mainly MVFR, with areas VFR possible. Likely RA. Wednesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, Chance SHSN. Thursday: VFR. NO SIG WX.
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&& .HYDROLOGY... As of 355 AM EST Saturday...A 48-hour period of anomalously warm temperatures will affect the region from Monday through Wednesday. Periods of rainfall, modest winds and dewpoint temperatures climbing into the 40s to lower 50s will foster rapid snowmelt across the entire area. Still some variability shown with this afternoon`s modeled 48-hr QPF, though the general consensus is for two day totals averaging from 0.5 to 1.5 inches, heaviest north. Taking this all into account, modest to substantial river rises look highly probable starting Monday night and continuing through Wednesday, supported by NAEFS/SREF MMEFS hydrograph data. While widespread open water flooding is not expected, several rivers may approach minor flood. Given the numerous ice jams in place from the substantial thaw this past January, localized high water/flood concerns near these features will also remain a concern. As future data helps hone the forecast in the coming 36-hours, a Flood Watch will likely be necessary for most if not all of the forecast area during this period. && .CLIMATE...
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Here are the current record high temperatures for February 20th and 21st: Record High Temperatures: ...............Feb 20th....Feb 21st.... BTV.............58 (1981)...59 (1981)... MPV.............56 (1994)...57 (1953)... MSS.............63 (1994)...62 (1953)... St. Johnsbury...60 (1981)...62 (1981)... Record High-Minimum Temperatures: ...............Feb 20th....Feb 21st.... BTV.............50 (1981)...49 (1981)... MPV.............47 (1981)...47 (1981)... MSS.............47 (1994)...41 (1981)... St. Johnsbury...40 (1981)...46 (1981)...
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Neiles NEAR TERM...Neiles/RSD SHORT TERM...Hastings LONG TERM...Hastings AVIATION...Banacos HYDROLOGY...JMG CLIMATE...TEAM BTV

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