Area Forecast Discussion
Issued by NWS Burlington, VT

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357 FXUS61 KBTV 201109 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 609 AM EST Fri Jan 20 2017 .SYNOPSIS... Relatively quiet weather will persist across the region through the upcoming weekend with mainly cloudy skies and very mild temperatures. A more significant weather maker is looking more likely to affect the region Monday night into Tuesday with potential significant accumulations of snow or mixed precipitation. Behind this system continued mild temperatures with on and off chances of rain and snow shower activity are expected by the middle to later portions of next week. && .NEAR TERM /THROUGH SATURDAY/...
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As of 609 AM EST Friday...Overall forecast remains in decent shape as of 600 am. Did tweak hourly temperatures and dewpoints and also made some adjustments to sky cover through the morning/afternoon, leaning more heavily toward WRFARW/WRFNMM output which is capturing current trends well. Again, sky cover and the degree to which we can achieve some spotty afternoon partial clearing will be the biggest near-term forecast challenge. Have a great day. Prior discussion... Quiet conditions continue today as pronounced and blocking upper ridge remains parked across the northeast. With lingering moisture trapped beneath a semi- permanent subsident inversion the timing and coverage of any partial clearing today will remain the biggest forecast challenge. Background flow does trend southerly over time however, and with the inversion weakening slightly the prior idea offering at least some breaks in the overcast still appears reasonable by afternoon in many spots. Time will tell though as we`re still near the annual bottom in regard to weakness in insolation. As has been the case over the past few days temperatures will remain remarkably steady, climbing only some 4 to 6 degrees from our overnight lows - generally from 35 to 41. By tonight into Saturday we`re still advertising a weakening impulse and associated spotty light precipitation to arrive from the southwest over time. Mid-level warm thermal advective processes are rather unimpressive and with the described weakening trend as system runs into our blocking ridge I expect rather scant, very light QPF at best across the area. Some minor concern that where surface temperatures do drop near or slightly below freezing some spotty very light -fzra and/or -fzdz will be possible. Indeed FRAM model output does show a light glaze of a few hundredths of an inch here and there across the SLV into portions of the Dacks and Vermont later tonight into the morning hours on Saturday. However, given the expected spotty, light QPF coverage will only mention in our Hazardous Weather Outlook at this point. As boundary layer temperatures warm by late morning on Saturday any threat of spotty light icing will end. With little airmass change very uniform temperatures will continue with overnight lows in the upper 20s to lower 30s (mid 20s northeast VT) and highs on Saturday in the upper 30s to lower 40s.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... As of 345 AM EST Friday...Model guidance showing plenty of low level moisture will be over the region Saturday night and Sunday which will trapped below a low level temperature inversion, with a weak upper ridge over the region. Expecting mostly cloudy skies for Saturday night and Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 345 AM EST Friday...GFS and ECMWF models showing a ridge of high pressure at the surface and aloft over the region Sunday night, so have lowered superblend pops Sunday night and will keep the region dry Sunday night. Plenty of low level moisture still will be present over the region Sunday night, so expecting skies to be cloudy Sunday night. Models continue to show a prolonged period of unsettled weather from Monday through Thursday. Models continue to show a surface low over the mid Atlantic states on Monday, underneath a closed upper low. Models bring this moisture slowly northward into the region mainly Monday afternoon, as a ridge of high pressure at the surface and aloft will be over the Canadian maritimes. This moisture will spread northward by a negative upper trough closed upper low over Pennsylvania late Monday night and Tuesday. Models continue to hint at a mixed precipitation event from Monday through Tuesday, with chances for rain, sleet and snow across the region from Monday through Tuesday. Expecting precipitation to wind down late Tuesday night, as an upper ridge builds into the region. The region will see a brief break early Wednesday, before another system approaches from the Great Lakes by late Wednesday bring more chances for rain or snow across the region Wednesday and Thursday. Temperatures expected to remain above normal in the long term portion of the forecast. && .AVIATION /12Z Friday through Tuesday/...
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Through 12Z Saturday...BKN/OVC MVFR/VFR cigs and light winds generally expected over the next 24 hours though some partial clearing in the 18Z-06Z time frame will be possible. Difficulty lies in degree to which synoptic inversion and trapped moisture can thin over time. Confidence only modest that partial clearing will occur at any given terminal. After 06Z weakening system approaching from the southwest may spark a spotty light shower or spotty light freezing rain where surface temperatures are near freezing. Coverage of pcpn quite scant so have omitted discrete mention at this point. Outlook 12Z Saturday through Tuesday...Areal coverage and cigs heights associated with plenty of low level moisture continues to be the aviation focus for Friday night into Saturday. A few sprinkles or flurries possible Saturday with general mvfr mountains to vfr valleys. Next system spreads a wintry mix across our taf sites late Monday into Tuesday with widespread mvfr to ifr conditions likely...along with breezy southeast downslope winds possible at Rutland.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...WGH LONG TERM...WGH AVIATION...JMG/KGM

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