Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 202039 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 339 PM EST Mon Feb 20 2017 .SYNOPSIS...
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High pressure will build eastward across the North Country tonight bringing mostly clear skies, diminishing winds, and chilly temperatures. Morning lows early Tuesday will be in the single digits to mid teens across the region. A weak mid-level disturbance approaching from the west will bring increasing cloudiness and developing south winds on Tuesday, with light precipitation Tuesday night. Precipitation will fall mainly as light rain. However, pockets of light freezing rain are possible east of the Green Mountains, and may result in a few icy spots. Well above average temperatures are expected through the remainder of the week, with a strong area of low pressure passing to our west expected to bring widespread rainfall Friday night through Saturday night.
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&& .NEAR TERM /THROUGH TUESDAY NIGHT/...
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As of 936 AM EST Monday...Tranquil weather conditions this evening and overnight as 1030mb surface high pressure drifts ewd from sern Ontario with dry deep-layer RH profiles. Skies are already clear across the North Country at 20Z, and anticipate north winds (currently 10-15mph) diminishing as ridge axis moves overhead and PBL stabilizes under clear skies. Expecting a strong low level inversion to develop, with the coldest readings tonight in the deeper valleys within the northern Adirondack Region and Northeast Kingdom (near 0F). Lows elsewhere will be in the upper single digits to mid teens, likely warmest near Lake Champlain. For Tuesday, a shortwave ridge crests across the area with sfc ridge shifting to our east into the Gulf of Maine by afternoon. This will induce a southerly gradient flow with surface winds increasing to 10-20 mph, with gusts to 25mph during the afternoon hours (especially with channeled flow in the Champlain Valley). The 12Z NAM RH profiles suggest increasing mid-upper level clouds by 18Z from west to east ahead of next shortwave trough across the Great Lakes. Despite increasing clouds, should see warmer temps with highs in the upr 30s to lwr 40s. Mid-level height falls and trough axis shift thru quickly during Tuesday night. Low-levels remain relatively dry, and overall it appears that approaching precipitation will undergo a dissipating trend as the trough axis moves thru Tuesday night. Maintained Likely PoPs during the overnight period, but QPF values only 0.05-0.10" for most locations, and period of precipitation will likely only span 2-3 hrs in most spots. Vertical temperature profiles with continued south winds support mainly rain with lows in the mid 30s. That said, should see pockets of temps near freezing as the precipitation moves thru in spots east of the Green Mtns, and have gone with a light ZR/R for the ern half of VT. A few hundreths of an inch of freezing rain is possible, and introduced mention in the Hazardous Weather Outlook as a few icy spots are possibly for travelers overnight Tuesday night. We will continue to monitor.
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&& .SHORT TERM /WEDNESDAY 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 MONDAY/... 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 /20Z 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...Banacos NEAR TERM...Banacos SHORT TERM...MV LONG TERM...MV AVIATION...Banacos

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