Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 261928 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 328 PM EDT Fri Aug 26 2016 .SYNOPSIS... Fair and seasonably warm weather will prevail across the region into Sunday as high pressure dominates the sensible weather pattern. The next chance for scattered showers will occur by later Sunday into Sunday evening as a weak front crosses the area. Behind this system a return to fair and dry weather is expected for early next week. && .NEAR TERM /THROUGH SATURDAY/... As of 245 PM EDT Friday...A quiet 24-hour stretch of weather is expected across the area as surface high pressure across southern Canada combines with deep subtropical upper ridging over the southeastern states to provide broad-scale subsidence and mainly clear skies. Other than some patchy mist/fog across favored locales later tonight skies should be mainly clear through the period with no rain expected. Temperatures generally a blend of bias-corrected model output offering overnight lows in the 50s to near 60 and highs on Saturday from 78 to 85 or so under moderate humidity levels. Winds light. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... As of 327 PM EDT Friday... The mid-level pattern beginning on Saturday night will feature geopotential height rises from an anomalous ridge centered over the mid--Atlantic states. Increasingly more neutral to weak mid-level height falls are then anticipated later Sunday into Sunday night associated with more unsettled weather. Saturday Night: Much of the area should remain dominated by subsidence associated with building 500 mb heights. The one exception will be along the outer periphery of the ridge primarily across St. Lawrence County and along the Canadian border counties where at least mid to high-level cloudiness is expected. Due to the spatial differences in cloud cover, expect central and southern areas to remain locally cooler with more radiative cooling versus the more cloud-covered areas. Lows should run about +5 to +10 degrees warmer than normal - in the 50s to mid 60s. Sunday: Mid-level ridge axis begins to shift eastward with variable cloud cover increasing through the day. I suspect that precipitation chances through the first part of the day to be limited given neutral heights and lack of a good trigger, with chances ramping up into the high-Chance range for the afternoon. NAM-based instability values are in the 500 J/kg range with LI`s barely negative so there is a limited potential for thunder, with mainly showers predominating. Since areas to the south are likely to see more early breaks, I`ve raised highs up some in this area and correspondingly lowered them to the north. Highs should then range in the upper 70s to mid 80s, above 30-year climo normals by a couple degrees. Sunday Night: Ongoing showers and/or thunderstorms to progress eastward through midnight with PoPs decreasing into the Slight Chance range, with a weak/nebulous frontal passage anticipated during the overnight. 925 mb temps still around +18C by 12z Monday and mostly cloudy skies keep temperatures in the upper 50s to mid 60s. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 327 PM EDT Friday... 500 mb shortwave trough associated with frontal passage moves through early Monday with lingering slight-chance PoPs trending dry by Monday afternoon. 12z GFS/ECMWF guidance then point to a pattern change in mid-levels across North America, with amplified ridging building into central North America and a cyclonic gyre setting up across the Northeastern states beginning around the end of August.Temperatures begin around 30-year climo normals to end August,closing what has proven to be a warm meteorological summer across the North Country, with a trend near to below normal by early September as upper low and its thermal trough overspread the area.The more active period of weather in the extended is around Wednesday with a seasonably strong frontal passage heralding the change toward cooler-than-normal temps. Given the amplified nature to the upper-level pattern by mid- week, I generally sided closer to the slower and cooler ECMWF idea into Thursday and Friday. && .AVIATION /19Z Friday THROUGH Wednesday/... Through 18Z Saturday...VFR through the period with mainly scattered cumulus bases in the 035-045 AGL range through 00Z, then SKC. Patchy IFR/LIFR br/fg possible at KMPV/KRUT/KSLK in the 06-12Z time frame tonight. Mixed signals on potential br/fg occurrence given dry advection regime with MOS-based guidance most bullish. Confidence moderate on occurrence but given morning rainfall, at least some added low level moisture input will be present overnight with light winds aloft. Winds generally light west to northwesterly 5-10 kts through 00Z, then light and variable thereafter. Outlook 18Z Saturday through Wednesday... 18Z Saturday through Wednesday...mainly VFR through the period with high pressure. Two main threat periods for scattered showers and brief MVFR conditions - Sunday afternoon/evening, then again Tuesday afternoon/evening with weak trough passages. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...Loconto LONG TERM...Loconto AVIATION...JMG

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