Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 182014 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 314 PM EST Sat Feb 18 2017 .SYNOPSIS...
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A ridge of high pressure will slide east of New England tonight, with a weak mid level trough passing to our north across Quebec Sunday into Sunday night. This system will bring the possibility of light rain or snow showers, primarily later Sunday into Sunday night, with the best prospect for light precipitation in the form of snow showers across the Northern Green Mountains and northern Adirondacks. We`ll see increased clouds for Sunday, but temperatures will remain in the upper 30s to lower 40s for valley highs. Dry and seasonably mild weather is expected Monday and Tuesday with high pressure in place. The next weak mid- level disturbance approaching from the west will bring chances for light mixed wintry precipitation Tuesday evening through Tuesday night. A more significant precipitation system is possible Friday into Saturday. At this time, it appears the system at the end of the week will bring windy, mild, and rainy conditions. Temperatures are generally expected to be above average this week.
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As of 310 PM EST Saturday...Seeing some melting snow across the region this afternoon under nearly full sunshine and with 2-m temperatures reaching the mid-upr 40s, and locally into the lower 50s across the St. Lawrence Valley of NY. Readings at 20Z include 48F at BTV, 50F at SLK, and 53F at MSS. NWP thermal profiles have generally been too moist/stable at low-levels with current warm advection regime over the existing snowpack. As such, it appears low-level moisture and cloudiness is overdone in most of the models for tonight, and winds are too light. Seeing gusts 25-30kts at times in the Champlain and St. Lawrence Valleys, and that should continue until around sunset. Moderate p-gradient remains in place tonight as well, so anticipate continued mixing overnight with winds 5-10kts and veering into the SW and eventually into the west for Sunday morning. The 850mb thermal ridge (+8C per RAP analysis at 17Z over Lake Ontario) will also crest over the North Country will see temperatures much more mild than last night. Generally looking at lows in the upr 20s to lower 30s, warmest around Lake Champlain and in the St. Lawrence Valley. A few deeper valleys should decouple east of the Green Mtns, and may see some localized readings in the low-mid 20s in those locations. For Sunday, will see mid-level height falls along the intl border associated with shortwave trough moving across srn Quebec. This nrn stream wave is associated with limited moisture, but continued veering of the low-level wind profile will set up a favorable NW upslope flow regime, especially Sunday aftn into the first half of Sunday night. Thus, looking for increasing cloudiness areawide Sunday, with occasional light snow showers developing across the higher terrain, and occasional flurries/sprinkles across the nrn valleys. At the surface, it does appear that a weak cold front will push swd into the region late Sunday aftn into Sunday evening, with better chances for snow showers briefly Sunday evening thru about 06Z Monday. Daytime highs Sunday generally expected in the upr 30s to lower 40s, and then falling back into the mid 20s with nw winds and stronger CAA regime Sunday night. May see a few slick/icy spots across higher elevation roads/passes, but overall snow accumulations later Sunday/Sunday night only expected to be a coating to 2"...highest from Mt. Mansfield to Jay Peak.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 350 AM EST Saturday...Mid/upper level flow will be west/northwest during this time period as weak surface cold front pushes across our region. The combination of upper level energy in the jet stream winds aloft...along with a narrow ribbon of mid level moisture will interact with upslope flow to produce chance pops on Sunday Night mainly in the mountains. Thermal profiles cool enough to support mostly snow...with maybe an inch or two accumulation by Monday...especially northern Greens. Otherwise...modest low level cold air advection occurs on Sunday Night into Monday with progged 850mb temps dropping between -10c and -12c...supporting highs mid 20s to mid 30s Monday. Surface analysis shows 1030mb high pres nosing into our region Monday Night...supporting clear skies and light winds...with ideal cooling expected. Thinking lows will range between 0f and +15f depending upon location...with strong low level inversion developing as warming aloft occurs. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 350 AM EST Saturday...High confidence in much above normal temperatures during this time period...resulting in significant snowmelt...especially across the valleys. Next chance of valley rain showers and mixed rain/snow in the mountains will be Tuesday into Weds. Weak short wave energy in the fast flow aloft...along with narrow axis of enhanced 850 to 500mb moisture will move from west to east across our cwa between 06z and 18z Weds. QPF will generally be between 0.10 and 0.25 with no hydro issues anticipated. Plenty of uncertainty with regards to magnitude and timing of our next system late next week into next weekend. We still have plenty of time to sort out the details over the next 5 to 7 days...associated with thermal profiles and mid/upper level trof evolution...along with eventual track of surface low pres. Progged 850mb temps between 2c and 4c on Tuesday support highs well into the 40s to near 50f...but with ridge of high pres directly overhead...mixing will be limited so have kept temps in check. If we had no snow pack and better mixing...thermal profiles would support highs well into the 50s on Tuesday with plenty of sunny. Still mid/upper 40s in the valleys with sun and light winds will feel really nice...with mid 30s to lower 40s in the mountains. Minor cooling with more clouds hold temps mainly in the mid 30s to mid 40s on Weds...before more warming occurs for Thursday into Friday. Developing southwest flow and progged 850mb temps between 3c and highs well into the 40s with a few 50s possible in the warmer valleys with lows mainly in the mid 30s to lower 40s Thursday into Friday. Expecting much less snow depth in the valleys by the end of the week...with some increases on local waterways. && .AVIATION /20Z Saturday THROUGH Thursday/... Through 18z Sunday...VFR conditions are expected to persist at the TAF locations through the period with passing mid to upper level cloudiness. Main concern through early this evening will be gusty south to southwesterly winds, sustained at 10-15kts with gusts up to 25kts at BTV/MSS. Toward sunset, may see localized LLWS develop at SLK/RUT/MPV if boundary layer can sufficiently decouple. Still some uncertainty on this, so haven`t included in the 18Z TAFs, but will continue to monitor. Otherwise, anticipate winds 5-10kts, and gradually shifting into the west and eventually west-northwest during the day Sunday. Outlook 18z Sunday through Thursday...Will see periods of HIR TRRN OBSCD through 12Z Monday with mtn snow showers expected across the Adirondacks and nrn Greens. Any precipitation will be light. In terms of the TAF locations, any light pcpn most likely to affect MPV/SLK. Another shortwave trough approaching from the west will bring a period of light rain/snow Tuesday night with brief intervals of MVFR conditions possible. Significant precipitation is currently not expected during the outlook period. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos SHORT TERM...Taber LONG TERM...Taber AVIATION...Banacos is the U.S. government's official web portal to all federal, state and local government web resources and services.