Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 181442 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 942 AM EST Sat Feb 18 2017 .SYNOPSIS... High pressure slides to the east today, putting the North Country in south to southwest flow. Temperatures will moderate considerably, with valley high temperatures in the upper 30s to lower 40s for both Saturday and Sunday. Also, a weak upper level disturbance will bring increasing clouds, with a slight chance for light rain or snow showers, mainly Saturday night into Sunday. The next chance for widespread precipitation will arrive the middle of next week. && .NEAR TERM /THROUGH SUNDAY/...
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As of 939 AM EST Saturday...Have made some upward adjustments to wind gusts and temperatures from the Champlain Valley wwd based on observational trends. It appears the models are having difficulty with low-level WAA over the snowpack, keeping lapse rates too stable and not realizing the extent of the turbulent mixing in the PBL already this morning. Have seen observed gusts to 26kt at BTV, and should continue to see gusts 25-28kt in the Champlain Valley thru mid-afternoon. Consistent with that, raised afternoon high temperatures another degree or two, going with 46F this afternoon at BTV and generally low-mid 40s areawide. Skies will remain mostly sunny with just passing - and mostly thin - cirrus. Previous Discussion...Clouds eroding from W to E this morning. Will likely see some sun before more clouds move in. Above normal temperatures as strong 850-700mb WAA develops in southwest flow. Expect winds to increase and become gusty this afternoon especially in the Champlain and St. Lawrence Valleys with gusts up to 20-30 mph. Under this WAA, expect max temperatures in the upper 30s to mid 40s today - even with some clouds from a weak northern stream shortwave trough. This shortwave will also bring a chance for a few sprinkles/mtn snow showers tonight into Sunday. Min temperatures tonight will range in the low-mid 30s in the valleys and upper 20s above 1000-1500ft elevation. Winds are expected to subside overnight as well, shifting west towards Sunday morning. Mid level vorticity looks to push southward across portions of the North Country on Sunday, especially in the afternoon, keeping the chance of showers over the mountains.
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&& .SHORT TERM /SUNDAY NIGHT 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 FRIDAY/... 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 5c...support 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 /15Z Saturday THROUGH Wednesday/... Through 12z Sunday...VFR conditions persist through at least the next 12 hours. Winds will start light out of the S-SE, then shift S-SW during the daylight hours on today, with increasing gusts of 15-25kts through this evening. Otherwise MVFR cig expected to develop as warmer air moves in over cold snowpack. This will likely result in MVFR stratus developing during the evening/Eal overnight hours. Winds are expected to subside after 06Z as the low level jet begins to weaken and exit east. Outlook 12z Sunday through Wednesday... Will see periods of HIR TRRN OBSCD through 12Z Monday. Any precipitation will be light, mainly isold/sct light rain or snow showers during Saturday night into early Sunday. Significant precipitation is not expected during the outlook period. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos/KGM NEAR TERM...Banacos/KGM SHORT TERM...Taber LONG TERM...Taber AVIATION...KGM

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