Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 201806 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 106 PM EST Mon Feb 20 2017 .SYNOPSIS... North winds will provide the North Country with cooler temperatures and dry conditions today with increasing sunshine. Clear skies and calm winds this evening will allow temperatures to quickly fall before warming during the pre-dawn hours Tuesday. A weak disturbance will spread a wintry mix of precipitation in the mountains and mainly rain in the valleys on Tuesday Night into Wednesday...with only minor accumulations expected. The trend of much above normal temperatures continue for most of the week...with more rain arriving Friday into Saturday. && .NEAR TERM /THROUGH TUESDAY/... As of 936 AM EST Monday...Visible satellite trends indicate continued clearing trend across the region with clouds eroding last across e-central into nern VT. Have made slight adjustments based on current observations, but forecast is generally on track. Previous Discussion...Increased hourly temps by 2 to 4 degrees across the board due to slowly than expected cooling associated with breezy northwest winds and low level cold air advection. Thinking temps will fall another several degrees through 15z...before becoming steady and increasing during the afternoon hours. Highs mainly teens mountains summits to mid 30s warmer valleys...especially lower ct river valley near VSF. Otherwise...the combination of low level upslope flow and leftover moisture continues to produce some clouds especially from northern NY into the mountains of VT and parts of the CPV. Expecting these clouds to dissipate by late morning with mostly sunny skies this afternoon under building surface high pres. Water vapor showing a very amplified and active pattern across the CONUS with trof over the northeast...ridge central Plains...and deep trof over the inter- mountain west. The combination of dry air aloft/subsidence behind departing short wave energy and building ridge will produce increasing amounts of sunshine today...under breezy northwest winds. Our forecast area continues under modest 925mb to 850mb cold air advection through 15z today...with progged 850mb temps dropping between -12c and -14c...before warming again. This makes for a tricky high temp forecast...especially with warm temps to start...but will trend toward the warmer side of guidance with highs ranging from the upper teens mountain summits to l/m 30s warmer valleys. A couple of mountain flurries are possible...especially northern Greens through 15z today...otherwise...soundings show drying with mostly sunny skies by this afternoon. Tonight..1031mb high pres is over northern NY at 00z and shifts into eastern VT by 06z...before moving into central New England by sunrise on Tuesday. This will provide ideal cooling conditions through midnight...before winds shift and warming aloft occurs. Expecting a strong low level inversion to develop with coldest values in the deepest/protected valleys with lows ranging from 0F SLK/NEK to mid/upper teens CPV and Southern SLV. I would expect large ranges between the cold valleys and warmer midslope and summit regions overnight. Tuesday...Short wave ridge shifts across our region as mid/upper level moisture and associated 500mb energy approach our western cwa by 00z Weds. Southerly 850mb winds of 25 to 35 knots will produce moderate low level waa with progged 925mb to 850mb temps climbing above 0C by 18z Tuesday. The developing fast southwest/west 500mb winds of 45 to 55 knots will help to quickly push a ribbon of enhanced 850 to 500mb rh from west to east across our region after 18z...with some light rain arriving by sunset over the Saint Lawrence Valley. Looks like some cooling occurs east of the Greens with temps quickly dropping to near 0c by 00z support a threat for pockets of freezing rain and sleet. Thinking some wet bulb cooling will result in areas of sleet...especially northeast kingdom of VT on Tuesday evening. Any qpf thru 00z Weds will be light and under tenth of an inch. Meanwhile...temps warm into the upper 30s to mid 40s for highs. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 339 AM EST Monday...Fast moving warm frontal system with westerly flow aloft along with narrow and weakening ribbon of high and mid level moisture will produce a progressive narrow axis of rain/snow/mix of light precipitation Tue night into Wednesday. Thermal profiles still showing mostly rain in the valleys but a mix of precipitation possible in the Adirondacks and possible freezing rain east of the Green Mountains as colder air lingers through Wednesday morning. QFP looks to be one to two tenths in the Dacks and Greens with some downslope shadowing likely here in the Champlain Valley associated with 850mb winds of 30 to 45 knots. Mild surface flow from the south and southwest will continue to keep temps above seasonal norms with Wednesday highs in the 40`s and pushing 50 in the Champlain Valley with overnight lows in the mid to upper 30`s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 339 AM EST Monday...Well above seasonal temperature trend continues late week into the weekend with developing eastern CONUS mid/upper level ridging. The next storm system continues to look like it will come Friday into Saturday with a low pressure system tracking north and west of our region. Thursday sees a weak short wave move to the north of the CWA with some warm moist advection ahead of a weak cold front which passes through late in the day or Thu eve. Highest chances for precipitation will be in the north and mainly in the form of light rain showers. High temperatures will range in the upper 40s to around lower 50`s with 925-mb temps of 3-8C north to south but cooling below 0C late Thursday night. Rising 500mb heights forecast along with primary low pressure tracking north and west of our region through the Great Lakes Friday through Saturday. Models have backed off potential secondary low near the NE coast, keeping it much further to the southeast, opening the door for even warmer conditions for Saturday before precipitation moves in. ECMWF shows temperatures in the Champlain Valley to reach nearly 60 degrees, so have opted to trend closer towards the warmer temps with highs in the mid 50`s. Things still look like we`ll be affected first by a warm front Fri evening/Fri night and cold occluded front Sat night before things quiet down on Sunday as the storm exits the region. Looks like a mix of precip may fall with the warm front on Friday followed by mainly windy and mild with rain showers on Saturday, before changing back to snow showers Sat late night. Sunday will see a return to closer to normal temps with highs in the mid to lower 30`s. && .AVIATION /18Z Monday THROUGH Saturday/... Through 18Z Tuesday...High pressure building ewd from sern Ontario will bring mostly clear skies and VFR conditions to the region through the TAF period. Will see increasing clouds above 15kft after 12Z Tuesday as high clouds advance from W-E ahead of the next trough across the Great Lakes. Winds generally north this afternoon at 10-12kts, becoming light and variable as boundary layer stabilizes around sunset. As the high pressure system shifts to the east, will see winds developing from the south toward daybreak Tuesday, increasing to 10-12kts with gusts to 20kts at BTV by 18z Tuesday. Outlook 18Z Tuesday through Saturday... A weak trough will bring periods of light rain, with pockets of freezing rain east of the Green Mtns during Tuesday night. Brief MVFR conditions are possible with this system, mainly during the pre-dawn hours Wednesday. Generally returning VFR with high pressure Wednesday afternoon through Friday morning. Warm front approaches from the southwest Friday afternoon with increasing chances for rain and periods of MVFR/IFR conditions. Will also see possible sfc wind gusts locally in excess of 25kts with low-level turbulence and wind shear late Friday through Saturday as deep low pressure passes to our west across the Great Lakes and Ontario. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Banacos/Taber SHORT TERM...MV LONG TERM...MV AVIATION...Banacos is the U.S. government's official web portal to all federal, state and local government web resources and services.