textproduct: Burlington

WHAT HAS CHANGED

As of 206 PM EST Saturday...

There have been no significant changes to the previous forecast. Temperatures and winds remain on track.

KEY MESSAGES

As of 206 PM EST Saturday...

1. Dangerous cold with wind chills of 20 to 40 below zero expected through Sunday Night.

2. A potential clipper low pressure system is possible Tuesday into Tuesday Night with potentially accumulating light snow.

3. No significant or impactful weather expected Tuesday night through next weekend with temperatures trending toward mid-February normals.

DISCUSSION

As of 206 PM EST Saturday...

KEY MESSAGE 1: Dangerous cold will continue today as northwest winds associated with an approaching ridge slides east behind the arctic cold front from this morning. Much of the area is already experiencing below zero wind chills as wind gusts increase to 20 to 30 mph, with all of northern New York already below zero for actual air temperatures. An Extreme Cold Warning remains in effect for the Adirondacks and St. Lawrence Valley in New York until 1 PM Sunday for wind chills between -20F and -40F, with a Cold Advisory for the rest of the region across the Champlain Valley and northern and central Vermont from 6 PM tonight through 1 PM Sunday for wind chills between -20F and -30F. If you must be outdoors, please make sure to dress for very cold conditions. Frostbite can start to affect exposed skin in as little as 10 minutes in these sorts of wind chill ranges, so hats, gloves/mittens, and warm layers for your core will be crucial.Strong caa from the northwest will continue to steepen lapse rates through this evening into tonight resulting in good vertical mixing and continue gusty conditions, primarily across the Adirondacks, the Champlain Valley, and along the spine of the Greens. Temperatures tonight will continue to fall overnight with air temperatures bottoming out in the minus teens across northern New York, and the minus single digits in Vermont, with minus teens in the higher terrain. The coldest wind chills will occur close to sunrise Sunday when radiative cooling peaks with wind chills near -20F to -25F in Vermont, and near -30F to -40F in northern New York and the spine of the Greens. Anyone with outdoor plans should consider altering and/or delaying outdoor activities this weekend.

Winds will weaken slightly for the day Sunday, but only down to 10 to 20 mph, which will keep wind chills below zero for the entire day. Wind chills will slightly "improve" to -5F to -15F during Sunday afternoon, but will return to dangerous cold levels Sunday night. While the Extreme Cold Warning and Cold Advisory expire tomorrow early afternoon, additional Cold Advisories may be needed for Sunday night. Northwest winds will continue Sunday night, but a steep inversion near 1000-1500ft agl may develop overnight, which would lead to colder valley floors as compared to mountain summits. Sunday night lows may be near -5F to -15F in the valleys, but only 0F to -5F above 1500ft agl. Adding to the complex temperature forecast, winds will slacken across the valleys, and become limited to the higher terrain (15 to 25 mph), as well as some models suggesting lingering lower clouds, especially over the high terrain. If the inversion were to develop, it would likely trap low clouds across the higher terrain, reducing the radiative cooling processes, but a fresh snowpack and sinking air from the higher terrain could be enough to counteract the inversion. Regardless, Sunday night into Monday will remain cold with high pressure building, resulting in wind chills returning to near -20F to -25F, with additional Cold Advisories possibly needed. KEY MESSAGE 2: A potential clipper like low pressure system will move through the area Tuesday into Tuesday night with chances for accumulating light snow. The system will be moving into a very dry air mass left behind by the high responsible for our cold this weekend, which will limit the overall snow potential. That being said, there will be some marginal frontogenesis, particularly over the Champlain Valley with some waa snow showers. The DGZ base in the current GFS soundings is notably high up to 8000ft, however, it is only a few thousand feet thick which would lead to more needle-like snow, and smaller flakes. Additionally, the forcing rapidly shifts east Tuesday night, along with any associated moisture. NBM probabilistic guidance denotes a 40-60% chance for most of the region of seeing 2 inches of snow or more, but only up to a 20% chance of 4 inches or more, mainly in the upslope regions of the northern Greens. The snow becomes more orographically driven along the upslope regions of the northern Greens by late Tuesday night.

KEY MESSAGE 3: Medium range deterministic, ensemble and AI guidance is coming into better agreement with the overall synoptic pattern for mid-week through next weekend featuring the continuation of a broad upper trough over the Northeast and ridging over the central CONUS through Friday, with the ridge shifting over the east coast on the weekend. Upslope snow showers across the central/northern Greens/Dacks will likely linger Wednesday into Thursday morning before surface high pressure builds in and dominates the regions weather through the end of the forecast period on Saturday with dry conditions expected. Temperatures finally look to trend towards mid- February normals with highs generally mid-20s to low-30s and lows in the low/mid teens above zero.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18Z Sunday...Overall conditions will remain largely variable across the forecast area for the remainder of the day with MVFR/VFR ceilings and IFR/MVFR visibility persisting in areas of very light snow and blowing snow. After 00Z, conditions will improve to VFR for all sites with snow ending except at KSLK where a low level inversion should keep ceilings locked in at MVFR into Sunday morning and potentially beyond. Gusty WNW winds will persist through 00Z as well for all sites up to around 25kts, thereafter tapering off to less than 15kts except for KBTV and KMPV where gusts continue.

Outlook...

Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHSN. Wednesday: Mainly MVFR, with local IFR possible. Chance SHSN. Wednesday Night: MVFR. Slight chance SHSN. Thursday: Mainly MVFR, with local VFR possible. 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. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Cold Weather Advisory from 6 PM this evening to 1 PM EST Sunday for VTZ001>011-016>021. NY...Extreme Cold Warning until 1 PM EST Sunday for NYZ026-027- 029>031-034-087. Cold Weather Advisory from 6 PM this evening to 1 PM EST Sunday for NYZ028-035.