Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 151428 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 928 AM EST Mon Jan 15 2018 .SYNOPSIS... High pressure overhead will keep the area dry through the daytime hours today. Overnight tonight, a weak low will bring some light snowfall lasting through Wednesday afternoon. Following this system, a return to more zonal flow will keep temperatures near seasonal norms. A few weak upper level disturbances could bring some light showers to the North Country through the early weekend. There is the potential towards the end of the weekend into early next week for a more significant frontal system to push through and bring some more focused precipitation. && .NEAR TERM /THROUGH TUESDAY/...
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As of 928 AM EST Monday...Temperatures still running on the cold side and have been slow to warm. Have tweaked temperatures to account for this slower trend...but highs in the teens still look good at this point. No other changes needed at this time. Previous Discussion: Quiet but cold weather continues overnight as a surface arctic high centered over southeastern Canada shifts northeastward. Under the high, winds are light, allowing for effective radiational cooling in the early overnight hours. Even with the high clouds moving through, a cold polar airmass is overhead, consisting of 850 mb temperatures -15 to -20 degrees C throughout the forecast area. In addition to the cold air mass, deep snowpack over the northern portion of the forecast area is also keeping overnight low temperatures 10 to 20 degrees below normal. Overall, a cold morning is in store for the North Country. As the surface high shifts further north and east today, general flow will gain an increasing southerly component through the afternoon hours in advance of a clipper low over the Great Lakes. The switch to southerly flow will advect in warmer air, resulting in widespread daytime high temperatures in the teens today and nighttime lows generally in the single digits tonight. By Tuesday, the warm air advection will allow temperatures to reach the 20s. The clipper low will weaken as it lifts northeastward out of the Great Lakes Region this evening. Weak warm air advection in the low levels ahead of the surface low and modest height falls ahead of an upper level trough will provide enough synoptic scale ascent to bring some light snow to the area starting tonight. Moisture associated with the system is lacking, so accumulations will be fairly light...generally thinking under 2 inches over northern New York and northern and central Vermont. Blocked flow Tuesday will allow for some orographic enhancement of snow on the western slopes of the Green Mountains. Southern Vermont will see the best moisture transport under a weak low level southwesterly jet, so expecting 2-4 inches over Windsor and Rutland Counties through Tuesday night.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 306 AM EST Monday...Consistent with previous forecasts, appears some light stratiform snowfall (1"-2.5") is likely across central/s-central/ern VT Tuesday night into Wednesday morning, with relatively high snow ratios expected. Positive tilt 700-500mb trough extending across sern Ontario into the Ohio Valley will be associated with development of a modest sfc low Tuesday night off the NJ coast per 00Z GFS/ECMWF solns. Overall idea is that this system will slowly deepen while tracking newd across sern MA/southeast of Cape Cod and into the Gulf of Maine. The 00z GFS and 00Z NAM are a bit further south and east with this system, resulting in lighter QPF amts across central/ern VT as compared to the 00Z ECMWF. Went with a compromise for now, resulting in a light snow accumulation of 1-2.5" across central/s-central VT for Tuesday night into Wednesday morning, with the highest totals across the srn Green Mtns. North and west of KBTV, not expecting much in the way of snowfall with this system, though as upper trough shears out across the area, there may be some scattered lake effect/orographic snow showers across the Northern Adirondacks late Wednesday into Wednesday night. Have included 30-40 PoPs across srn St. Lawrence and Franklin NY counties for this possibility. Clouds and moderating air mass will result in somewhat more seasonable temperatures thru the period. Will see lows Tuesday night mainly in the teens, with a few low 20s possible across the valleys of s-central VT. Temperatures will warm into the mid-upr 20s in most valley sections on Wednesday afternoon, before falling back into the teens for Wednesday night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 306 AM EST Monday...Main story during the long-term period will be continued moderation of temperatures across the North Country as W-SW low-level flow regime develops across the ern Great Lakes into the nern CONUS. While the warm up won`t be as dramatic as what was experienced last Friday, should see high temperatures rise into the upr 20s Thursday, low-mid 30s Friday, mid-upr 30s on Saturday, and potentially into the 40s for Sunday. Any precipitation is expected to be light, limited to potentially weak/fast moving mid- level northern stream shortwave troughs embedded in zonal flow, and detached from any more significant moisture from lower latitudes. Timing is uncertain in fast mid-upr tropospheric flow, but currently max PoPs only in the 20-30% for possible light snow showers Thursday, and potential mix of rain or snow showers over the weekend. There may be a more significant frontal system passing to our west Sunday night into Monday, bringing a wintry mix trending toward mainly rain based on expected low track and associated vertical temperature profiles. This system is at the very end - to just beyond - the current long-term forecast period, so we`ll continue to monitor trends. With ice jams likely still in place, may see some renewed hydro concerns toward the end of the weekend into early next week. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... Through 12Z Tuesday...Mainly VFR conditions and calm to light winds will prevail through the TAF period, with a general trend towards low VFR ceilings through the period. Expect scattered high clouds to thicken and lower to 100-150 AGL between 00Z and 06Z, then further lower to 035-060 AGL between 06Z and 12Z. The exception will be MSS/SLK, where ceilings are expected to drop to below 030 AGL by 09Z. Snow will spread over MSS/SLK by 09Z, reducing VFR visibilities to IFR. Outlook... Tuesday: Mainly MVFR, with local VFR possible. Chance SN. Tuesday Night: Mainly MVFR, with local VFR possible. Chance SN. Wednesday: Mainly MVFR, with areas VFR possible. Slight chance SN, Slight chance SHSN. Wednesday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Thursday: MVFR. Slight chance SHSN. Thursday Night: Mainly MVFR, with areas VFR possible. Slight chance SHSN. Friday: Mainly MVFR, with areas VFR possible. Slight chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...RSD NEAR TERM...Evenson/RSD SHORT TERM...Banacos LONG TERM...Banacos AVIATION...RSD is the U.S. government's official web portal to all federal, state and local government web resources and services.