Area Forecast Discussion
Issued by NWS Burlington, VT

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604 FXUS61 KBTV 240535 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1235 AM EST Fri Nov 24 2017 .SYNOPSIS... Surface high pressure will move eastward tonight, allowing for mainly cloudy skies tonight with scattered snow showers across the Adirondacks and northern Green Mountains. Friday will be milder with increasing south to southwest winds. Highs Friday will generally be in the low to mid 40s. A low pressure system passing to our north on Saturday will bring a trailing cold front across the North Country allowing for periods of rain or snow showers Saturday into Saturday night. Overall, temperatures will be trending above seasonal levels over the next 5 to 7 days. && .NEAR TERM /THROUGH TONIGHT/... As of 1007 PM EST Thursday...Starting to get some light snow off of Lake Ontario and a weak shortwave moving across southern Quebec Province. Should last a few more hours before flow becomes more northwest and precipitation tapers off. Going forecast has this covered well and no changes needed at this time. Previous Discussion... Relatively quiet weather through Friday night. Chilly air mass in place Thanksgiving afternoon in association with sfc ridge axis extending from central PA newd across NY and northern New England. Highs generally reaching the upr 20s to lower 30s this aftn...roughly 10deg below seasonal averages for late November. Meanwhile, a weak 700-500mb shortwave trough is moving ewd across sern Ontario and nrn NY, and this feature is bringing widespread mid-level clouds across our region despite the sfc ridge. This evening, it continues to appear that some lake effect snow showers will develop off of Lake Ontario as sfc ridge slides ewd and deep-layer SW flow develops. This is reflected especially in NAM-3km and BTV-4kmWRF forecasts showing a brief period of lake effect snow 00-06Z across the Route 3 corridor from Star Lake wwd across srn St. Lawrence county. Maintained a period of likely snow showers, with possible snow accumulations around 1" across srn Franklin NY and St. Lawrence counties. May also see a few flurries ewd across the Champlain Valley and especially into the Jay Peak area overnight with trajectories favoring ENEWD advection of the lake moisture mainly 06-12Z tonight. Low temperatures won`t be as cold as last night, generally in the mid-upr 20s with abundant cloud cover and above mentioned light snow shower or flurry activity. On Friday, strengthening p-gradient will bring breezy conditions, with S-SW winds 10-20 mph, with a few gusts to 30 mph in vicinity of Lake Champlain. Expecting a good moderation in temperatures, with Friday`s highs generally in the low-mid 40s. Should also see mostly sunny conditions. South winds continue Friday night as next shortwave trough moves ewd into the Great Lakes region. Shouldn`t see much direct impact from that system and attendant cold front until the daylight hrs Saturday, but the south flow will keep our temps mainly in the low 30s for overnight lows, except upr 20s across the nrn Adirondacks and mid-upr 20s for ern VT where some of the deeper valleys may decouple with stable PBL conditions. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... As of 245 PM EST Thursday...Models remains consistent in showing a shortwave trough and attendant cold front approaching the area during the day on Saturday, then passing east and south by Saturday night. Have largely maintained persistence in showing increased chances of rain showers through the day as skies trend mainly cloudy. Highest coverage should occur across the northern mountains, especially in the Adirondacks as southwest boundary layer flow transports lake moisture downstream. Overall QPF will remain light however, and generally less than a tenth of an inch. Temperatures to remain mild - mainly 40s under modestly gusty south/southwest flow. Rain showers then transition to snow showers from north to south and higher to lower elevations over time Saturday night while waning in overall coverage as cold front exits east and synoptic flow trends northwesterly. Some minor accumulations of a dusting to 2 inches will be possible by sunrise Sunday, mainly across the northern mountains. Lows near seasonable late November norms from the mid 20s to lower 30s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 245 PM EST Thursday...Much of next week will continue to favor a progressive synoptic flow pattern across the northern tier of the nation with several weak shortwave features bringing periodic light rain/snow shower chances interspersed by brief interludes of high pressure and quiet weather. Any threat of arctic air will remain bottled well north of our area with near seasonable temperatures expected under an average airmass of eastern north Pacific and southern Canadian origin. This is in contrast to what the moderately negative AO and NAO indices would typically predict (i.e. much colder). The best threat of additional light precipitation will occur Sunday into Sunday evening, and again by next Wednesday with passage of aforementioned shortwave energy. Again any precipitation or snow accumulations will be light. High temperatures to range through the 30s during Sunday/Monday and in the upper 30s to mid 40s from Tuesday onward. Lows mainly in the upper teens to mid 20s Sunday night/Monday night, moderating into the 25 to 35 range on average thereafter. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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Through 06Z Saturday...Widespread OVC VFR ceilings with brief periods of MVFR is expected through 12Z before ceilings lift from south to north and scatter out to FEW200/SKC this afternoon. Exception will be KSLK where southwest flow off Lake Ontario will keep IFR ceilings persistent through at least 12Z, possibly longer. All sites will be VFR by 18Z and remain VFR through the rest of the period. Winds will be mainly south/southeast at 6-10kts from KPBG eastward with some gusts this afternoon and evening up to 20kts at KBTV. Westward at KSLK and KMSS southwesterlies will prevail at 08-12kts with gusts to 20kts and likely some LLWS and turbulence after 23Z as a low level jet streaks in. Approaches over Lake Champlain will also be quite bumpy this afternoon and overnight with low level winds in excess of 30kts likely over the open waters. Outlook... Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: Mainly MVFR, with areas VFR possible. Chance SHRA, Chance SHSN. Sunday: Mainly VFR, with local MVFR possible. Chance SHSN, Slight chance SHRA. Sunday Night: Mainly MVFR, with local VFR possible. Chance SHSN. Monday: Mainly MVFR, with areas VFR possible. Slight chance SHSN. Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday: VFR. Slight chance SHRA.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/Evenson SHORT TERM...JMG LONG TERM...JMG AVIATION...Lahiff is the U.S. government's official web portal to all federal, state and local government web resources and services.