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WHAT HAS CHANGED

As of 230 PM EST Friday... The Winter Storm Watch has been upgraded to a Winter Storm Warning for portions of New York and central and southern Vermont as confidence in those areas receiving at least 7 inches of snow has increased. Further north, where there still remains uncertainty in snow amounts, the Winter Storm Watch remains in effect.

KEY MESSAGES

As of 230 PM EST Friday...

1. Dangerously cold conditions are expected tonight through Saturday morning, with wind chills of -20F to -40F expected. Risk of hypothermia and frostbite is unusually high due to the extreme nature of the cold, especially for vulnerable populations and anyone venturing outdoors without proper cold weather gear.

2. Several inches of moderate to heavy snow is looking likely for our region late Sunday through Monday. Travel will become hazardous, with the bulk of the snow occurring Sunday evening into Monday morning. Both the morning evening commutes on Monday will be impacted.

DISCUSSION

As of 230 PM EST Friday...

.KEY MESSAGE 1: Very dangerously cold conditions are expected tonight and Saturday, with wind chills of -20F to -40F areawide. Therefore, the Extreme Cold Warning remains in effect from 7 pm Friday to 1 pm Saturday. This will be the coldest airmass of the season so far, and given the extreme nature of the cold, the risk of hypothermia and frostbite will be unusually high. This is especially true for vulnerable populations and anyone venturing outdoors without proper cold weather gear.

A cold front lies poised just to our north this afternoon, and it will move through later today into the evening, ushering in a much colder arctic airmass in its wake. There hasn't been much change to the forecast; temperatures will fall sharply this evening and overnight. Winds will remain gusty, as well; low level lapse rates will steepen under cold air advection, keeping us well mixed into the overnight hours. Today's gusts around 30 mph will continue into the evening then wane through the latter half of the night as the strongest winds exit to the east. But with lows to be -5F to -20F, even relatively light winds will be enough to result in brutally cold wind chills. As such, wind chill are still expected to be -20F to -40F, with the most extreme conditions in the northern Adirondacks and the Northeast Kingdom. We are urging people to stay indoors if possible, especially vulnerable populations like the elderly and children. If you must be outdoors, please make sure to wear plenty of warm gear, including gloves or mittens and a hat. Any exposed skin will be susceptible to frostbite in just a few minutes. And don't forget about your pets; bring them inside if at all possible.

The cold continues well into Saturday morning, but winds will continue to subside through the day. We should see increasing sunshine, as well. Still, wind chills will remain well below zero through the afternoon as daytime ambient temperatures will remain in the -5F to +5F range. Proper precautions still need to be taken even during the afternoon. Saturday night will be very cold once again, but with little wind. Lows are still expected to range from around 0F to around -20F. There is still some uncertainty in exactly which locations will be coldest, however, as high clouds will be increasing overnight, limiting radiational cooling. Still, additional cold weather headlines may be needed.

KEY MESSAGE 2: Long story short, confidence in at least several inches of snow across our entire forecast area continues to increase. The 12z model guidance has continued with the trend toward higher snowfall totals, particularly in central/southern VT and portions of NY. Therefore, the Watch has been upgraded to a Winter Storm Warning for Essex Co, NY and Addison, Washington, Orange, Rutland, and Windsor Co in VT. Snowfall amounts more than 7 inches are pretty darn certain in these areas. Further north, it's still a touch more questionable, which is why the Winter Storm Watch remains in effect.

Overall, there hasn't been a significant change in the expected weather pattern. An upper trough will dig into the Great Lakes on Sunday, then swinging eastward into the Northeast CONUS on Monday. This will allow a coastal low to deepen as it lifts northeast Sunday into Sunday night, eventually moving south of Cape Cod and out toward the open Atlantic. As noted by previous forecasters, deep moisture will be drawn northward into New England. We continue to see strong frontogenesis 700-850 mb progged to lift into southern New England, skirting across central/southern VT Sunday night before quickly moving east Monday. With ample forcing provided by the strengthening coastal low and the incoming upper trough, the deep moisture and temperatures remaining below 0C through the column continue to point toward a prolonged period of steady moderate to heavy snow, particularly Sunday night into early Monday. The snow will slowly wind down on Monday, though there is still some model differences in how long it ultimately sticks around. An inverted trough extending northwest from the coastal low into our region will help to keep snow going longer, but models disagree on the strength and duration of this feature. Regardless, we'll probably see some wrap around snow showers in the northern mountains for a period of time after the main snow ends as flow turns to the north/northwest.

All of this to say, we remain on track for much of the region to receive several inches of snow. Given the strength of the high to our north, there could be a fairly tight cutoff on the northern edge of the precipitation shield. That being said, the chance of even our far northern zones seeing 4+ inches remains high, at 70-85%. This drops to 50-65% for 7+ inches along the international border, while central/southern VT into the southern Adirondacks indicate 80-90% chance of seeing warning criteria snow. With that in mind, we did upgrade the watch to a warning for those more southern areas with higher certainty. Further north, we'll allow more time for the models to come to a consensus on how far the 7+ inch line goes.

While there's still some time for things to change somewhat, we feel fairly confident that the warning areas will see a general 9-16 inches of snow, with locally higher amounts in the higher terrain. Further north, it'll be somewhere 5-12 inches depending on your location. We wouldn't be surprised to see some higher totals should some mesobanding set up on the northwest side of the coastal low, but that remains to be seen. Regardless, snow ratios will be around 20:1, making for a light, fluffy snow. So impacts will mainly be travel related, as roads will be snow covered and visibility could be reduced, especially given the fluffiness of the snow. While isolated trees or branches down can't be totally ruled out, the snow just isn't going to be the wet, heavy type that favors more utility- based impacts.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...VFR conditions generally prevail across the region, with some scattered snow showers bringing periods of MVFR/IFR conditions. Models are indicating snow showers should be moving out of our area by about 02z. Gusty winds continue, generally out of the west/northwest. Gusts diminishing towards the morning. Some MVFR ceilings are lingering, mostly at KSLK/KEFK/KMPV but all terminals are expected to return back to VFR by early morning.

Outlook...

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

CLIMATE

Record low maximum temperatures are possible on Saturday; below are the current records:

KBTV (Burlington area): -4 in 1907 KPBG (Plattsburgh area): 0 in 1976 KSLK (Saranac Lake area): -10 in 1936 KMSS (Massena): -5 in 2004 KMPV (Montpelier): 0 in 2004 SJBV1 (St. Johnsbury): -3 in 1907

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...Extreme Cold Warning until 1 PM EST Saturday for VTZ001>011- 016>021. Winter Storm Watch from Sunday afternoon through late Monday night for VTZ001>007-016-017. Winter Storm Warning from 1 PM Sunday to 1 AM EST Tuesday for VTZ008>011-018>021. NY...Extreme Cold Warning until 1 PM EST Saturday for NYZ026>031- 034-035-087. Winter Storm Watch from Sunday afternoon through late Monday night for NYZ026>031-087. Winter Storm Warning from 1 PM Sunday to 1 AM EST Tuesday for NYZ034-035.