textproduct: Burlington

WHAT HAS CHANGED

As of 227 PM EST Thursday...

Winter Storm Warnings were issued for areas near and east of the Adirondacks and southern Green Mountains, with Winter Weather Advisories issued elsewhere.

KEY MESSAGES

As of 227 PM EST Thursday...

1. Very difficult travel is expected during the Friday afternoon or evening commute as a burst of heavy snowfall expands northeastward. Snow will be wet initially, which could result in isolated power outages, before turning drier and lighter Friday night into Saturday.

2. Quiet seasonable weather early next week.

DISCUSSION

As of 227 PM EST Thursday...

KEY MESSAGE 1: Conditions remain quiet and seasonable through tomorrow morning. We'll be watching the area of low pressure over the Midwest today, which will scoot to the northeast and occlude tomorrow morning near Lake Michigan. Strong frontogenesis downstream with a surge of PWAT northeastward along the boundary as it moves steadily into our region. The elongated upper level low and associated divergence downstream of this low will support strongest vertical motion and potentially heaviest precipitation in southern/western portions of the region, although the forcing does seem to slide eastward enough such that heavy precipitation rates are possible throughout our region. While snowfall amounts for this event are not particularly noteworthy, this event will feature a combination of intense snowfall rates and fairly wet snow to become very hazardous for travel.

Onset of deep moisture and associated precipitation has slowed just a touch based on the latest model guidance, although there remains some spread. Typically models can be a little too slow on the precipitation onset with dynamic, warm advection scenarios, so would not be surprised if precipitation begins when hourly PoPs are only "chance" (under 55%). That being said, while Winter Weather Advisories and Winter Storm Warnings uniformly begin at 10 AM, most likely timing of onset of snow is between 2 and 4 PM across central portions of Vermont and much of northern New York, between 4 and 6 PM near the I-89 to Route 15 corridor northwestward into Clinton County, and 6 and 8 PM in northeastern Vermont. As such, southern areas are most definitively going to see very difficult travel for the afternoon/evening commute, but periods of heavy snow are still expected areawide. Snow to liquid ratios will begin for most areas near 10:1 (wet), but expect enough snow to become increasingly dry to limit risk of power outages to isolated in nature, with chances greatest where Winter Storm Warnings are in effect.

The latest snowfall amounts in the model blend have increased compared to the previous forecast, but there is a wider range in 25th to 75th percentile values than what one would like to see so close to an event. Some of the uncertainty is related to QPF/precipitation amounts, which is complicated by modest downsloping easterly flow in the western slopes of the higher terrain and possible convective elements in the precipitation with some modest elevated instability. north/northeastward extent of higher precipitation amounts in particular is more uncertain; if confidence increases on more widespread >0.6" liquid amounts, probabilities of 7" snowfall amounts would increase north of where warnings are in effect currently. Variations in snowfall will also be related to boundary layer issues early in the event, where precipitation may be a mix of rain and snow when rates aren't heavy enough in the eastern Champlain Valley and southern St. Lawrence Valley.

Snowfall will tend to linger throughout Friday night into Saturday as an inverted trough and low level convergence may support persistent light accumulations. Chances of appreciable snowfall will tend to diminish towards the south and east with time, although shallow northwesterly flow will develop to help promote upslope snow showers as ample moisture remains through the day. A narrow ridge will build into the area Sunday, supporting seasonable conditions and mainly dry weather.

KEY MESSAGE 2: A nor'easter is expected to miss the region well to the southeast Sunday into Monday, keeping any significant snow well to the south. Its only effects would be slightly enhanced winds and increased clouds. A separate shortwave will try to move into the region from the Great Lakes on Sunday but at most it would bring a few light snow showers. These could linger into Monday but any accumulation would be very light. The next more impactful storm looks to arrive in the Wednesday-Thursday timeframe. A low looks to track by to the west and up the St. Lawrence Valley, but warm-air advection should be limited ahead of it so much of the precipitation still looks to fall as snow.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

Through 18Z Friday...VFR conditions currently prevail at all terminals and that is expected to continue for the next 24 hours. There is a low chance that MVFR ceilings develop at SLK and MPV for a few hours later tonight but that is not expected at this time. Winds will be light or terrain driven during this time. Widespread snow develops tomorrow afternoon and continues through the evening, bringing widespread IFR visibility.

Outlook...

Friday Night: Mainly MVFR, with areas IFR possible. Definite SN. Saturday: Mainly MVFR, with areas VFR possible. Chance SN. Saturday Night: Mainly VFR, with local MVFR possible. Slight chance SN. Sunday: Mainly VFR, with local MVFR possible. Slight chance SN. Sunday Night: Mainly VFR, with local MVFR possible. Slight chance SN. Monday: Mainly VFR, with areas MVFR possible. Slight chance SN. Monday Night: Mainly VFR, with areas MVFR possible. NO SIG WX. Tuesday: VFR. NO SIG WX.

EQUIPMENT

The KMPV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. Terminal Aerodrome Forecasts will continue, but amendments to those forecasts will be suspended.

NOAA Weather Radio station WXM-44, transmitting from Mt. Ascutney, Vermont, on frequency 162.475 MHz is non- operational at this time. NWS technicians have diagnosed the problem, but repairs will likely not be able to occur for quite some time due to circumstances beyond our control. Therefore, the time of return to service is currently unknown. The following NOAA Weather Radio transmitters may be able to provide service during this outage: WWG 50 from Burke Mtn, VT at 162.425 MHz and WNG 546 from Hanover, NH at 162.525 MHz.

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS and there isn't an estimated return to service at present. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Winter Weather Advisory from 10 AM Friday to 10 AM EST Saturday for VTZ001>011-016-017. Winter Storm Warning from 10 AM Friday to 10 AM EST Saturday for VTZ018>021. NY...Winter Weather Advisory from 10 AM Friday to 10 AM EST Saturday for NYZ026>031-087. Winter Storm Warning from 10 AM Friday to 10 AM EST Saturday for NYZ034-035.