textproduct: Burlington

SYNOPSIS

A powerful low pressure system tracking to our west will bring a period of freezing rain tonight into tomorrow, eventually transitioning into plain rain. Later tomorrow, a cold front will drop temperatures back below freezing with a few snow showers. Heading through the week, our weather will remain wintry with cold temperatures many chances for snow showers.

NEAR TERM /THROUGH MONDAY/

As of 632 PM EST Sunday...Radar showing freezing rain expanding quickly toward our cwa this evening with precip expected to develop in the next 1 to 2 hours. Water vapor shows impressive rapidly developing cyclone over the central Plains, with potent s/w energy/dynamics helping to enhance thunderstorm development in the Ohio Valley. In addition, strong-deep layer moisture and thermal advection continues from the northern Ohio Valley into central NY, as precip continues to expand in areal coverage. Upstream 3 to 4 hour qpf amounts at BUF are impressive with >0.75" occurring, its this heavy axis of precip with elevated instability that will move acrs our cwa later tonight into Monday morning. I have bumped up qpf amounts to match upstream trends and latest CAM output. Given crnt temps in the upper teens to mid 20s, most precip starts as freezing rain, but a switch occurs first along portions of the northern Dacks and central/southern CPV, associated with downslope warming. Elsewhere, cold air and freezing rain lingers the longest over the SLV and east of the Greens, including the CT River Valley. Still thinking ice accumulations of 0.15" to 0.30" in the advisory and 0.50" to 0.75" in the ice storm warning looks reasonable, given latest 21z HRRR and RAP data. Just minor tweaks made in grids attm.

The gusty west to southwest winds on backside, especially parts of the SLV and downslope portions of the eastern Greens could produce additional power outages on Monday night into Tuesday. Travel will be extremely difficult late this evening and especially during the Monday morning commute.

Previous discussion below: A quickly deepening low pressure system will move northeast into the Great lakes region and occlude tonight into Monday. A secondary low will begin to develop just south of the region and become the primary low as it moves up into Atlantic Canada. With cold temperatures at the onset from the lingering effects of the polar high, the precipitation with the initial warm front will fall as freezing rain for most places tonight. A substantial warm nose will prevent snow on the front end. With the NBM and other guidance consistently keeping temperatures too warm during the day and overnight during the current airmass has, confidence is high that the precipitation will start as freezing rain almost everywhere.

As warm air advection continues through Monday morning, temperatures at the surface will gradually warm above freezing. This will likely start in parts of the northern Adirondacks and Champlain Valley, before eventually reaching the St. Lawrence Valley and protected hollows east of the Green Mountains last. Overall, ice accumulations look to be in the 0.2-0.5 inch range for most places, with a bit less in the Champlain Valley and parts of the northern Adirondacks. The most favored areas could see slightly over 0.5 inches.

Some model uncertainty remains with QPF and temperatures, and most of it is related to the development of the aforementioned secondary low. A quicker development, as long as it continues to be favored south of the region, will significantly cut down on the warm air advection and southerly surface winds, something like the HRRR and RRFS currently show. This would lead to freezing rain hanging on into the afternoon in many areas. With the NBM on the warmer side of the solutions and its tendency to struggle in freezing rain events, I blended in some temperatures from colder guidance, dropping temperatures east of the Greens and in the St. Lawrence Valley a bit. This generally puts the forecast in between the higher and lower guidance, but the overall gap is not too large and there is decent confidence with the overall idea of the forecast.

Temperatures should rise into the mid 30s to mid 40s briefly in the afternoon for most places. The current thinking is that everywhere should see a couple hours above freezing, though whether it is enough to melt all the ice accreted to trees and powerlines is in question, especially in the St. Lawrence Valley and areas east of the Greens where the cold air is entrenched the longest. Temperatures may not rise above freezing in parts of these places until the immediately after the cold front moves through in the afternoon and mixes the atmosphere. Cold air advection will be quite strong behind the front and everywhere should see temperatures falling below freezing by late Monday evening. Gusts will generally be in the 25-40 mph range, though locally higher winds are expected in the St. Lawrence Valley and far northern Adirondacks. This could present problems if the colder guidance verifies and temperatures in the coldest areas do not rise above freezing and ice remains on the powerlines and trees.

As the cold front moves through Monday afternoon and evening, a few heavy convective snow showers are possible. There will be a few with the initial cold front and another broken line looks to form over St. Lawrence County in the afternoon with lake enhancement. A quick coating is possible from these. WHile a flash freeze is not expected, quickly dropping temperatures in the afternoon and evening will cause untreated areas to quickly freeze.

SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/

As of 127 PM EST Sunday...Continued upslope snow showers will occur Monday night through Tuesday night from wrap around moisture. Westerly to northwesterly flow will keep most of the moisture from the Great Lakes to the south. Flow looks to be very unblocked during this time, so the highest amounts should fall along and east of the summits. Mostly westerly flow will favor the far northern Greens for seeing the most snow, particularly around Jay Peak. Strong winds and cold temperatures should cause wind chills to range between 0 and -15 Tuesday morning.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

As of 127 PM EST Sunday...A wintry weather pattern is expected throughout much of next week, with cool temperatures and chances for snow showers. A system moving across the region Wednesday into Thursday may bring some widespread light snowfall to the region, with the potential for some heavier snow showers and possible squalls along the boundary Wednesday night, although the details with this system need to be fine-tuned. Otherwise, cyclonic flow aloft will continue to bring chances for snow showers, especially across the higher terrain and portions of northern New York due to Lake Ontario. Temperatures throughout this time period will be on the cool side, with highs in the teens and low 20s and overnight lows generally in the single digits above and below zero.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Through 00Z Tuesday...Currently VFR conditions at all sites with light winds and cloud heights between 6000 and 12000 feet. Freezing rain and significant runway icing will develop between 01z and 03z across all of our taf sites. As precipitation develops expect cigs to lower toward mvfr conditions with periods of moderate freezing rain likely at most sites between 04z and 10z tonight and intervals of IFR. In addition, strengthening low level wind fields will result in developing wind shear and turbulence across our tafs sites by midnight and continue into Monday. Localized southeast gusts up to 25 knots possible at BTV/RUT with northeast at MSS. Freezing rain will transition to light rain at PBG/BTV/SLK and RUT by sunrise, while persisting at MPV/MSS and EFK thru mid to late morning on Monday. A sharp cold front sweeps across our taf sites after 18z with winds shifting to the west/southwest and becoming gusty at SLK/MSS, with Champlain Valley sites experiencing increase cigs by 21z.

Outlook...

Monday Night: Mainly VFR, with areas MVFR possible. Windy with gusts to 30 kt. Scattered SHSN. Tuesday: VFR. Windy with gusts to 30 kt. Chance SHSN. Tuesday Night: VFR. Slight chance SHSN. Wednesday: Mainly VFR, with areas MVFR possible. Chance SHSN. Wednesday Night: Mainly VFR, with local MVFR possible. Chance SHSN. New Years Day: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. Slight chance SHSN.

EQUIPMENT

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. Use extra caution when navigating the broad waters of Lake Champlain. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Ice Storm Warning until 4 PM EST Monday for VTZ004-006>008-010- 020-021. Winter Weather Advisory until 4 PM EST Monday for VTZ001>003- 005-009-011-016>019. NY...Ice Storm Warning until 4 PM EST Monday for NYZ026-027-034-087. Wind Advisory from 10 AM to 10 PM EST Monday for NYZ026-087. Winter Weather Advisory until 4 PM EST Monday for NYZ028>031- 035.