textproduct: Burlington

WHAT HAS CHANGED

As of 145 PM EST Monday...

A bit of a southward shift in model guidance with the Wednesday system means that areas across our northern zones will see less precipitation.

KEY MESSAGES

As of 145 PM EST Monday...

1. Chance for light snow showers tonight into Tuesday, with possible light drizzle or freezing drizzle.

2. Some snow will likely impact southern portions of the region on Wednesday and Wednesday night. Northward extent of this precipitation remains highly uncertain.

3. Seasonable late week and weekend conditions expected with additional chances of precipitation.

DISCUSSION

As of 145 PM EST Monday...

KEY MESSAGE 1: Light snow will move into our area from west to east overnight, beginning around 10 pm in northern New York and after midnight in Vermont. This warm front is lifting into our area, and facing some dry air which is in place this afternoon across our area. Temperatures overnight will dip into the lower 20s east of the Greens, with upper 20s to lower 30s across the rest of our area. There is potential for rain or light freezing drizzle to mix with the light snow towards early Tuesday morning. QPF with this warm front is expected to be light, generally a tenth of an inch or less of liquid equivalent. A half an inch or less of snowfall is expected. Only a hundredth of an inch or a glaze of ice is anticipated with better chances across the northern Adirondacks. By Tuesday afternoon high temperatures will warm into the mid to upper 30s areawide. Winds will be light during the day Tuesday, so some fog over snow will be possible as dewpoints also rise above freezing.

KEY MESSAGE 2: A powerful low pressure system over the northern Plains will occlude and stall out, but significant frontogenesis associated with the storm will support a weaker wave of low pressure to develop over the southern Great Lakes region and help produce a frontal zone of moderate to heavy precipitation. Confluent upper level flow out ahead of this wave due to a low pressure area lingering near northern Maine will keep precipitation from expanding northeastward as typically the case. Rather, a band of snow will have a sharp northward cutoff, which model consensus shows will be positioned somewhere in the vicinity of northern New York and northern Vermont. North of the frontal zone, the air will be very dry due to the anticyclonic flow of the incoming ridge behind the system near Maine. Relatedly, various ensemble model guidance shows a sharp gradient in precipitation chances; as an example, the latest run of the AIGEFS shows only an 11% chance of measurable precipitation in Burlington, 38% chance in Middlebury, and 76% chance in Rutland.

As such, it remains a highly difficult forecast for much of the northeastern US for Wednesday into Wednesday night. The relatively narrow frontal zone, with marginally cold temperatures for snow versus rain, will promote a fairly long duration of precipitation including a narrow band of impactful wet snowfall. Thermal profiles look fairly isothermal to preclude much mixed precipitation, and so we expect a wet snow or possibly mix of rain and snow especially with a farther north storm track. The latest deterministic model guidance generally has shifted a touch southward however, showing little impact for our region. This scenario would have snow spreading into far southern portions of northern New York and Vermont, make little northward progress during the daytime hours, and then gradually pull away Wednesday night. The resulting snowfall amounts would be very light, with maybe a narrow zone in our southern areas of only around 1" of new snow, possibly up to 2" in south central Vermont. Because of the duration/orientation of precipitation along the front, any northward shift will result in moderate snowfall amounts, and the current snowfall totals reflect this potential with storm totals near 4" in a swath over southern portions of the Adirondacks and southern Vermont. Ultimately, southernmost areas still look most definitively on track for fresh snow, and we'll monitor trends in the position of the front that will determine the actual snowfall details.

Following the snow/cloudy conditions for Wednesday, Thursday looks like a very quiet weather day; a large ridge of high pressure aloft and at the surface will support light winds and seasonable temperatures.

KEY MESSAGE 3: Temperatures will be near normal by the end of the week into the weekend but still cold enough to support some winter precipitation through wet-bulbing and dynamical cooling processes. Highs will be near 30, with overnight lows in the teens; slightly warmer temperatures in southern Vermont. Late Friday into Saturday, an upper low across the Great Lakes will occlude with a double barrel surface coastal low developing across the Mid-Atlanic. There is some decent mid to upper level forcing, with low to mid level frontogenesis from the Champlain Valley south into southern Vermont. The limiting factor with this system is the distance between the parent upper low in the Great Lakes and the coastal low which will lead to considerable stretching and thinning of the moisture field over the region. The coastal low does not appear to deepen much as it tracks northeast into the Canadian Maritimes, but some wrap around moisture could keep snow showers in Vermont into midday Saturday. Temperatures and dynamical cooling processes should keep any precipitation as all snow for the region. Current NBM probabilities depict a 50-70% chance of 2 inches of snow across central and southern Vermont and the Adirondacks; 40-50% across northern Vermont, and a 40-60% chance of seeing 4 or more inches of snow across central and southern Vermont. Model guidance is also beginning to key in on a potentially impactful coastal system Sunday into Monday. Overall ensemble member timing and track guidance still varies widely, but there are now a few ensemble members that draw a coastal system near Benchmark. Confidence is low right now, but this will be something to monitor over the next several days.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Through 00Z Wednesday...VFR conditions continue for the next few hours until precipitation moves in out of Canada. Radar imagery shows snow showers moving towards northern New York and Vermont out of southern Canada in the vicinity of the Great Lakes. MSS will see showers first around 03Z with showers and MVFR conditions spreading eastward by 06Z. Given temperatures right around freezing, today's snowmelt will likely not refreeze overnight becoming a source for some fog/mist through the day. IFR conditions become increasingly likely 06-12Z as CIGs lower and in areas of snow showers. Since the quasi-stationary boundary will remain just south of the Adirondacks, this is a prime pattern for fog/drizzle after 12Z. Model soundings note some potential for drizzle, so SCT002-004 were added to account for lower CIG potential. Otherwise, widespread IFR is probable especially with slightly warming temperatures expected for the daytime hours resulting in more snowmelt to become a source for lower CIGs/VIS. Some improvement may occur late in the period as a southwesterly wind component picks up at MSS after 21Z.

Outlook...

Tuesday Night: Mainly VFR, with areas MVFR possible. Slight chance FZDZ. Wednesday: VFR. Chance SN. Wednesday Night: VFR. Chance SN, Slight chance FZRA. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. Chance SN. Friday Night: VFR. Likely SN. Saturday: Mainly VFR, with areas MVFR possible. Chance SN.

EQUIPMENT

The KMPV AWOS 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...None. NY...None.