textproduct: Burlington

WHAT HAS CHANGED

As of 218 PM EST Thursday...The Extreme Cold Watch has been upgraded to an Extreme Cold Warning for all of northern New York and much of Vermont for dangerously cold conditions Friday night through Saturday morning. A Winter Storm Watch has been issued for Rutland and Windsor Counties from Sunday afternoon through late Monday night.

KEY MESSAGES

As of 218 PM EST Thursday...

1. Localized hazardous travel is expected this afternoon, tonight, and again on Friday due to a combination of scattered snow squalls and a lake effect snow band. Additional squalls are likely on Friday. Sharply reduced visibility due to both falling and blowing snow, and a rapid accumulation of snow will make for slippery and hazardous travel, including for this evening's commute and again on Friday.

2. Dangerously cold conditions are increasingly likely late this week, with wind chills of -20F to -40F possible. 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.

3. A Winter Storm Watch has been posted for Rutland and Windsor counties for the potential of 7 inches or more of snow late Sunday through Monday, which could be expanded northward given trends in guidance.

DISCUSSION

As of 218 PM EST Thursday...

.KEY MESSAGE 1: Scattered snow squalls are ongoing across the region this afternoon, with near white out conditions at times. We are also starting to see winds pick up as well, with gusts of 30-40 mph being reported. This will cause areas of blowing snow and further lowering visibilities. These squalls will gradually die down this evening, though a few moderate to heavy showers can't be ruled out overnight. We've already had reports of snow accumulations exceeding 1 in/hr, but this really heavy snowfall is brief. So overall accumulations with these snow squalls will mainly be 2 inches or less.

Meanwhile, a narrow lake effect band will develop off of Lake Ontario as gusty west winds continue overnight. This band will waver through southern St Lawrence County tonight and on Friday. Snowfall totals will be 3 to 9 inches in southern St Lawrence County, with the highest totals along and south of Route 3. Hence the Winter Weather Advisory remains in effect until 7 pm Friday.

Either from today's squalls or the lake effect band, heavy snowfall rates and gusty winds will make for localized treacherous travel due to visibility reduced to below 1/2 mile and rapid snow accumulations resulting in slippery roads. Anyone driving today and tonight needs to remain alert and be prepared for highly variable driving conditions. You may want to consider postponing travel until after the squalls/lake effect have ended.

Unfortunately, we could see another round of squalls on Friday as a secondary, arctic front will move through. With better frontal forcing, the squalls should be less scattered, forming a few broken lines through the afternoon and evening. Like today, briefly heavy snowfall combined with gusty winds will make for treacherous travel, so please plan ahead if you will be out on the roads.

.KEY MESSAGE 2: Very dangerously cold conditions are expected Friday night and Saturday, with wind chills of -20F to -40F areawide. Therefore, we have upgraded the Extreme Cold Watch to an Extreme Cold Warning, effective 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.

As the aforementioned arctic cold front crosses our region on Friday, a much colder airmass will spread southward in its wake. 925mb temperatures will approach -28 to -30C, with overnight ambient temperatures to drop well below zero by early Saturday morning. The issue on Friday night will be the continued breezy conditions, as strong cold air advection will keep us mixed through much of the overnight hours. Friday's daytime gusts will gradually wane as the strongest winds exit to the south and east. But with lows to be -5F to -20F, even relatively light winds will be enough to result in brutally cold wind chills. As it is, gusts up to 25 mph will be possible through at least the first half of the night, with sustained winds likely still 5-10 mph by daybreak Saturday. The result of this will be brutally cold wind chills of -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 3: The potential for a widespread moderate snowfall has increased acrs our cwa late Sunday thru Monday. Large scale synoptic setup shows strong southern stream energy/sub-tropical moisture racing acrs the Gulf Coast States on Sunday, while potent northern stream energy digs acrs the northern Plains. Its this digging s/w energy that has caused amplification of downstream ridging off the East Coast and deepening of mid/upper lvl trof, while pulling deeper moisture into central/northern New England. The question is how much moisture can be advected northward with strong 1040mb high pres anchored over northern Maine. Still a large spread in guidance with regards to snowfall accumulations acrs our fa, with the GFS showing the least amount, while ECMWF/UKMET/CMC and both the AI GFS/ECMWF showing potential warning criteria snowfall up to the International Border.

As northern/southern stream energy phases double barrel low pres with strong cad signature on lee-side of the Appalachians Mtns develops on Sunday. The mid lvl ascent associated with an axis of moderate to strong 7h fgen forcing wl shift from the mid Atlantic states toward central New England on Sunday night, while potent northern stream energy moves directly overhead. This synoptic scale lift and advection of deeper sub-tropical over our very cold air mass in place wl produce a period of moderate snowfall with high fluff factor. Did note even in the drier GFS sounding profiles an extremely deep DGZ from the sfc thru 22,000 feet with near saturation in terms of ice in the cloud. This moisture/thermal profiles indicate the potential for big time fluff factor acrs our cwa, which could result in higher snowfall totals if enough moisture is present. Snow ratios could be in the 20 to 25 to 1 ratio. The primary impacts would be difficult travel late Sunday into Monday, with moderate snowfall rates and very low visibilities. NBM indicates probability of 7 inches or more of 60% or greater along and south of a OGS to BTV to 1V4, with 60 to 80% or higher for snowfall of at least 4 inches or more.

Mid/upper lvl trof along with some mid lvl goodies for enhanced synoptic scale ascent lingers into Monday night with additional light snowfall likely, that is why the watch is thru 06z Tues. This lagging energy causes sfc low pres to stretch and linger just east of MA, which could result in light snow prevailing into Tues, especially as northwest upslope flow develops. Eventually moisture decreases and snow showers taper off.

Temps wl continue to be much below normal for Sunday through the middle of next week, especially Sunday into Monday with cold northerly sfc winds and plenty of cloud cover.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00Z Saturday...Snow squalls have ended across the region this evening. Additional snow showers will impact SLK periodically this evening with more IFR or lower conditions likely. Also, gusty south/southwest winds of 15 to 30 knots will create areas of blowing and drifting snow, especially at SLK/MSS and EFK thru this evening. Conditions slowly trend toward VFR in the valleys and MVFR/VFR in the mountain taf sites by 06z tonight. More scattered snow showers are likely again on Friday associated with an arctic boundary. Too hard to pinpoint timing on this activity this far out though.

Outlook...

Friday Night: VFR. Slight chance SHSN. Saturday: VFR. NO SIG WX. Saturday Night: VFR. NO SIG WX. Sunday: VFR. Chance SN. Sunday Night: MVFR and IFR. Definite SN. Monday: Mainly MVFR and IFR, with areas VFR possible. Likely SN. Monday Night: VFR. Chance SN. Tuesday: 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 from 7 PM Friday to 1 PM EST Saturday for VTZ001>011-016>021. Winter Storm Watch from Sunday afternoon through late Monday night for VTZ011-019>021. NY...Extreme Cold Warning from 7 PM Friday to 1 PM EST Saturday for NYZ026>031-034-035-087. Winter Weather Advisory until 7 PM EST Friday for NYZ029.