textproduct: Burlington

SYNOPSIS

The severity of cold air will lessen through the weekend, with higher elevations especially trending milder. A powerful low pressure system tracking to our west will bring us a period of freezing rain Sunday night into Monday and then gusty winds and chances for snow showers later Monday into Tuesday. Blustery and cold weather with additional snow shower chances will persist into the new year.

NEAR TERM /THROUGH SUNDAY/

As of 213 AM EST Saturday... *Light snow will end early this morning, with otherwise quiet weather through the weekend.

Stubborn high pressure to our north will reinforce seasonably cold conditions as the wave of light snow departs early today. The large scale pattern looks almost identical to yesterday, only with a somewhat moderated air mass such that temperatures will be less bitterly cold.

A rare extended period of strongly anticyclonic flow remains in store for the weekend. For sensible weather, it's a tricky sky forecast today as low level moisture only gradually erodes. Skies will be slow to clear, but based on satellite imagery showing clearing expanding eastward near Ottawa at this hour, think eventually sunny skies will be common. Have continued to trend temperatures colder for tonight with ideal radiational cooling likely. As surface temperatures plummet and temperatures aloft warm notably, an unusually sharp inversion is on track to develop. Localized freezing fog may also develop, with greatest potential in the Adirondack region where low level moisture looks a bit richer. On Sunday it will be the quiet before the storm with very light winds, abundant dry air, and the typical lowering/thickening of clouds with time. Impressive modification of the air mass aloft on southwesterly winds, while the surface wind remains light, will translate to much milder temperatures above 1500 feet than in the lower elevations in an atypical pattern.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/

*** Significant freezing rain is expected Sunday night into Monday. Flat ice accumulations in the range of 0.25"-0.5" are possible for much of the region. This type of ice would produce hazardous, icy road conditions for the Monday morning commute, and weight down tree limbs enough for isolated power outages.

Busy weather Sunday night through Monday with a potent low pressure system passing to our west will include freezing rain, a brief warm up, gusty winds, and backside snow showers for the higher terrain.

Mid and upper level ridging on Sunday ahead of the system's warm front will set the stage for freezing rain as the dominant precipitation type as a large warm layer aloft builds. Temperatures at the surface will remain cold under the influence of our high pressure system that will drift further to our east, but by being northeast of our region we will see little warming. Onset of freezing rain seems to be mainly after 7 PM, with greatest likelihood in the 1 AM to 7 AM period. Unfortunately, the latest model blend has trended wetter as consensus for a more robust warm front is evident. Greatest liquid amounts are forecast in southern portions of the region where threat of greatest ice amounts exists, dependent on terrain influence. The magnitude of southeasterly winds as rain moves into the region will be a factor to how quickly temperatures warm on the downslope side of the higher terrain. Generally greatest opportunity of dodging significant icing is over the western Adirondacks (eg. Tupper Lake westward to near Route 11). Highest confidence in greater ice amounts exists in the northern St. Lawrence Valley, southwestern Essex County New York, and most of Vermont east of the Green Mountain Spine, especially in south central Vermont (eg. from near Barre south to near Ludlow). Portions of northeastern Vermont may see some warming off of the White Mountains prior to steadier precipitation arriving to lead to lower amounts of freezing rain. For now have gone with a more pessimistic ice forecast to show more of a reasonable worst case scenario in the official forecast at this time, but please monitor the latest forecasts as we update them in the coming days. Winter Weather Advisories can be expected at the very least ahead of this event, with some potential for Ice Storm Warnings for areas like in the St. Lawrence Valley.

Secondarily, we will see increasing south to southwest winds during the day as we briefly get into the storm's warm sector ahead of its cold front. With 850 millibar temperatures pushing 10 degrees Celsius in the morning, temperatures could dramatically warm in localized areas that do mix out their inversion.

It is unclear how much of a triple point feature develops and where it will track out ahead of the primary and powerful occluded low pressure system that will pass to our northwest. This feature would support some convective showers during the afternoon and sharply falling temperatures with a shift to west-southwesterly winds, such that precipitation type will switch to snow in the Adirondacks, and potentially in much of Vermont later on towards evening. The more concerning winds will probably be immediately behind this front in the St. Lawrence Valley with terrain enhancement, where potential Wind Advisory level gusts will need to be monitored with such a deep low pressure system and associated southwesterly low level jet moving in during the afternoon. Top of the mixed layer winds above 55 knots are evident in forecast soundings. Needless to say, this could be an additional hazard with regards to any significant ice accumulation that persists on tree limbs.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

As of 159 AM EST Saturday...This period includes the backside of our ice event through the New Year's holiday.

SFC low and front move through the area Monday afternoon with falling temperatures in increasing cold WNW winds for ptype to changeover to snow showers with the main snow shower activity being across northern areas and favorable WNW mountains Monday night- Tuesday. Strong 850mb with cold air advection will allow good mixing of winds thus windy late Monday through Tuesday night. WSW flow across the eastern Great Lakes will allow for some LES in the Adirondacks with -SHSN and instability -SHSN in northern VT mountains.

A weak shortwave and surface reflection is still expected Wednesday with more snow showers that may linger into New Years Eve plans. Nothing to impactful but worth monitoring if traveling is in your plans.

Thereafter...continued cold cyclonic flow across Great Lakes, NE and Eastern Canada. This will keep things cold with potentially more -SHSN later New Years and Friday. Energy in this flow late New Year's may develop a SFC low near Southern New England and we'll need to see how this unfolds to see if it's anything more than -SHSN for us with the upper trof.

AVIATION /10Z SATURDAY THROUGH WEDNESDAY/

Through 06Z Sunday...Mainly light snow falling across most of our TAF sites at 06z but will be exiting by 09-10z. MVFR-IFR with the snow then should primarily VFR with VSBY but some MVFR CIGS possible. Winds are generally light 5-7 kts or less but NE 8-15 kts at KMSS but that will diminish with time this morning.

Drier air is poised for the region, but there is a developing inversion and this could lead to some low clouds for some but with time later this afternoon it should be SCT with VFR conditions. Light winds < 7kts for all sites.

One concern, especially at KSLK is strengthening low level inversion where bkn-ovc005 deck and reduced Vsby due to ice fog is possible overnight.

Outlook...

Sunday: VFR. Slight chance FZRA. Sunday Night: Mainly VFR, with local IFR possible. Chance FZRA. Monday: Mainly IFR, with areas MVFR possible. Definite RA, Definite FZRA, Definite SN. Monday Night: Mainly VFR, with areas MVFR and IFR possible. Windy with gusts to 30 kt. Likely SN, Chance FZRA. Tuesday: VFR. Windy with gusts to 30 kt. Chance SHSN. Tuesday Night: VFR. Chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. 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...None. NY...None.