Area Forecast Discussion
Issued by NWS Burlington, VT

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158 FXUS61 KBTV 100854 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 354 AM EST Sat Dec 10 2016 .SYNOPSIS...
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A cold and blustery day is expected with scattered snow showers. Highs will only reach the teens mountains and 20s in the valleys today. Our next system arrives on Sunday Night into Monday with a widespread accumulating snowfall expected. Total snow accumulations will range from 3 to 7 inches by Monday afternoon. A slippery Monday morning commute is expected.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 353 AM EST Saturday...The coldest airmass of the season will be parked over our region today into Sunday...as northwest flow aloft continues. Forecast challenge today will be potential areal coverage of snow showers...as several weak features are showing up in water vapor and we have cold air moving over relative warm lake champlain water. Have bumped pops to chance across the Champlain Valley and western Slopes today...as water vapor shows weak ribbon of mid level moisture dropping southeast in the northwest flow aloft...along with weak 5h vort just north of the Great Lakes. This energy/moisture...will combined with low level cold air advection to produce scattered mainly light snow showers across the champlain valley and western slopes. Would not be surprised a few locations get a dusting to maybe an inch or two given the synoptic and mesoscale setup. By later this afternoon winds shift to more of a westerly direction and this will limit fetch across Lake Champlain...resulting in decreasing pops chances toward sunset. Progged 850mb temps drop between -16c and -18c today with 925mb temps between -13c and -15c...resulting in below normal readings. Thinking highs mainly in the teens mountains to mid 20s warmer valleys. For tonight...winds become light and variable as 1032mb high pres builds overhead. Big question will be if skies can clear with drying aloft and how temps are impacted. Soundings continue to show some moisture between 925mb and 800mb overnight...which supports clouds and slightly warmer temps. Low mainly in the single digits mountain valleys with fresh snow pack to mid teens champlain valley. if more clearing develops than anticipated...northeast kingdom and slk area could see first night of below 0f of the winter season. Sunday...relatively quiet and dry weather expected as we wait the arrival of our next system. Have mention some chance pops southern Saint Lawrence county as winds veer to the southwest winds...thinking weakening lake effect snow band may impact this region. Any accumulation would be light...given weak flow and developing shear. Based on warm air advection pattern and progged 850 to 500mb rh>70% off the gfs...have increased pops to chance by 00z across our southwest cwa. Thinking precip will quickly expand into our region...associated with strong developing low level southerly jet after 00z Monday. Temps continue below normal with highs mainly in the teens mountains to mid 20s valleys.
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&& .SHORT TERM /SUNDAY NIGHT/... As of 218 PM EST Friday...By Saturday night into Sunday generally quiet conditions are expected with surface high pressure being the dominant driver of sensible weather. A moderately moist, light westerly flow pattern argues for persistence in this period with partly cloudy skies and perhaps a few flurries or snow showers, especially across the higher terrain and to the lee of Lake Ontario across the southern SLV/western Dacks. Temperatures remain seasonably cold with lows more or less in the 5 to 15 above range and subsequent highs on Sunday in the 20s. By Sunday night our next system is progged to arrive over time as occluding cyclone across the upper Great Lakes drives strong moisture and warm occlusion northeast into our region. Thermal profiles solidly cold enough for all snow, which should arrive in steady fashion from southwest to northeast over time as robust isentropic lift in mid-levels interacts with the prime dendritic snow growth layer. South to southeasterly 925-850 mb flow also increases sharply during this time (30 to 50 knots) so valley shadowing effects will be possible at least to some extent with possible upslope enhancement along eastern facing slopes of the Adirondacks and Greens. As we draw closer to the event finer scale detail offered by the higher-resolution models should provide some additional value. However, a general accumulation of 2-4 inches by the Monday morning commute seems plausible at this point as temperatures hold steady, or slowly climb through the 20s. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 218 PM EST Friday...Best forcing for precipitation then swings through and north/east of the area Monday morning through early afternoon with best moisture advection/isentropic lift associated with the occlusion. Precipitation will taper off to very light snow/drizzle and/or freezing drizzle by afternoon as a pronounced dry slot works in aloft. Some light icing will be possible across portions of the area during the later part of the day, mainly across the eastern portions of the Dacks and eastern VT where sheltered sub-freezing air will be tough to scour out. Snow totals for the event fairly typical for a strong warm advective event - generally 3-7 inches with local variation. Highs on Monday mainly in the upper 20s to lower 30s in the Dacks and eastern Vermont, with lower to mid 30s in the Champlain and St Lawrence Valleys. The remainder of the forecast from Tuesday onward generally features broad west to northwesterly flow with periodic chances of snow showers as a large, modified arctic airmass persists across nearly the entire northern tier of the lower 48. There remains some disparity among solutions in regard to additional energy ejecting from the plains states east/northeast along the polar front by mid to late week and additional chances for steadier snows in our area. The eventual solution seems to hinge on the degree this energy can phase with a rather potent polar gyre dropping through central and eastern Canada, and the extent to which moisture can be drawn back north atop the polar boundary. Given the current uncertainty will maintain persistence here capping pops in the chance category as temperatures start seasonably cold and trend quite chilly by later next week as modified arctic air continues to bleed south and east from central Canada. && .AVIATION /09Z Saturday THROUGH Wednesday/... Through 06Z Sunday...Looking at VFR to MVFR ceilings through the forecast period. Scattered snow showers will exist through about 12z on Saturday...but visibilities will generally be in the VFR category. However...any snow showers will have the potential to briefly reduce visibilities into the MVFR category. West to northwest winds will continue to taper off early this morning and will generally be under 10 knots for the remainder of the period. Outlook 06Z Sunday through Wednesday... 06z Sunday through 06Z Monday...VFR under high pressure. 06z Monday through 00z Tuesday...Widespread MVFR cigs and IFR vsby in light snow. 00Z Tuesday through 00z Thursday...Mix of MVFR/VFR cigs with scattered snow showers locally reducing vsby to IFR at times, mainly at KSLK/KMPV. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...JMG LONG TERM...JMG AVIATION...Evenson/Lahiff

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