textproduct: Burlington

WHAT HAS CHANGED

As of 150 AM EST Thursday...

Confidence is increasing in lighter snow amounts and lower impacts for the snow today and tonight.

KEY MESSAGES

As of 150 AM EST Thursday...

1. A coastal low will bring widespread lower elevation rain and wet snow mainly above 1200 feet today and tonight.

2. High confidence for dry weather and above normal temperatures next week.

DISCUSSION

As of 150 AM EST Thursday...

KEY MESSAGE 1: A gradually deepening surface low will track from the Ohio Valley east over southern New England before heading off into the Canadian Maritimes today into tomorrow. Despite a favorable storm track for snow, a marginally cold airmass will be in place at the onset, especially at the surface due to a lack of Canadian high pressure to the north. Precipitation will enter southwestern areas this morning but very slowly make its way northeast during the day. By tonight, it should reach the Northeast Kingdom, but the heaviest rates will remain to the south. It will likely never reach the St. Lawrence Valley though. At the onset, surface temperatures will be in the 30s in most places, with low 40s in the warmest valleys. Steep lapse rates will exist with summit levels well below freezing, though a lack of a significantly dry layer will prevent significant wet-bulb cooling.

Precipitation will begin as rain in the valleys and snow at the summits. An estimate of initial snow levels is around 1,500 ft. Light rates and daytime occurrence will prevent significant accumulations at the onset outside the mountains. A weak November sun angle will limit some of the warming effects though. Heading into tonight, heavier rates should enter southern areas, and darkness will end any solar radiation. The combination of lowering temperatures due to dynamical cooling and nighttime cooling will allow snow levels to drop a bit, and especially allow for more efficient accumulations at higher elevations with higher snow ratios. By Friday morning, snow levels should be around or below 1,000 ft. While brief periods of snow are possible in the low valleys like the Champlain Valley and the Lower Connecticut Valley, temperatures will likely stay just above freezing and prevent accumulations other than maybe some slush on grassy-type surfaces.

As the low tracks to the east heading through Friday, cyclonic northwest flow will develop and maintain periods of upslope snow showers in the higher terrain through Saturday. Boundary layer temperatures will reach their lowest values Saturday morning, with most areas likely seeing temperatures in the 20s. However, that time period will likely be dry and prevent any snow from occurring in the valleys. Warm Lake Champlain temperatures will probably further limit the already marginal accumulations in the immediate Champlain Valley, especially with northwest flow off the lake and downsloping along the eastern Adirondacks.

Confidence has increased in a more southerly storm track and a less impactful event. Our deterministic most-likely scenario has snow amounts in the 2-5 inch range for the southern Adirondacks, central Greens and southern Greens around and above 2,000 ft. Areas between 1,000-2,000 ft look to be in the 0-2 inch range, and below 1,000 ft looks to be a slushy coating at most. The main area of uncertainty that remains is the potential for a mesoband to reach southern Vermont. If it reaches, brief accumulations are possible down to the valley floors due to dynamical cooling and an additional couple inches would be possible across the higher terrain. However, this should not significantly change the impacts.

At this point, the snowfall looks too light to cause power outages but far southern Vermont will have to be watched in case the mesoband comes in and stalls there for a couple hours.

KEY MESSAGE 2: Models continue to suggest we could see a few upslope snow showers along the western slopes of the Green and Adirondack Mountains Sunday night into Monday morning. This may yield some minor snow accumulation but otherwise not impactful. Increasing subsidence from a building deep layer ridge will bring an end to any shower activity by Monday afternoon. High pressure will remain entrenched across the region through the remainder of the week with the axis of the upper level ridge forcing a series of disturbances to push harmlessly to our north. Temperatures will warm throughout the week with high temperatures by Wednesday and Thursday climbing into the 50s, which will be slightly above normal for this time of the year.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Through 12Z Friday...Precipitation has been slow to overspread the area this morning. We've slowed down the onset of rain across the valleys and snow at the higher summits by a few hours. Nevertheless, the MVFR and IFR ceilings still looked to be slowly building into the area with most sites dropping to either MVFR of IFR by 16Z. KRUT/KSLK/KMPV will be the difficult sites today as temperatures will likely fluctuate in the mid to upper 30s which will support periods of rain, snow, or both at times. This will make visibilities tricky as any bursts of heavier precip will drive visibilities below 1 SM while prevailing visibilities will likely be 3+ SM. Rain will begin to change over to snow in valley locations after 6Z but will also be tapering off around the same time. Light northerly winds are currently being observed and will continue through the forecast period.

Outlook...

Friday: Mainly VFR, with local MVFR possible. Slight chance SN. Friday Night: VFR. NO SIG WX. Saturday: VFR/MVFR conditions possible. Chance SHRA, Slight chance SHSN. Saturday Night: Mainly MVFR, with local IFR possible. Chance SHRA, Chance SHSN. Sunday: Mainly MVFR, with local IFR possible. Chance SHRA, Chance SHSN. Sunday Night: Mainly MVFR, with areas VFR possible. Slight chance SN. Monday: Mainly VFR, with areas MVFR possible. NO SIG WX.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Winter Weather Advisory from 10 AM this morning to 10 AM EST Friday for VTZ018-019. NY...Winter Weather Advisory from 10 AM this morning to 10 AM EST Friday for NYZ034.