textproduct: Burlington

WHAT HAS CHANGED

As of 136 AM EST Saturday...

No significant changes were needed with this forecast package. The Extreme Cold Warning and Cold Weather Advisory remain in place.

KEY MESSAGES

As of 136 AM EST Saturday...

1. Widespread light snow showers with embedded moderate to heavy bands will continue through this morning, creating hazardous travel conditions. These will persist into the afternoon due to areas of blowing snow.

2. Dangerous cold with wind chills of 20 to 40 below zero expected today into Sunday.

3. No significant or impactful weather expected Weds into next weekend with temperatures trending toward normal mid February readings.

DISCUSSION

As of 136 AM EST Saturday...

KEY MESSAGE 1: Low pressure is currently drifting across our forecast area this morning, centered very near the international border. An arctic front is being dragged along in its wake, and as of this writing, has just crossed into the St Lawrence Valley. We've been seeing a period of mainly light snow across the area overnight, with accumulation generally ranging from just a dusting here in the Champlain Valley to perhaps an inch or two in portions of northern NY. As expected, a narrow band of intense snow has developed along the front; note that visibility in Ottawa went down to 1/2SM as the band went through there, with snowfall rates estimated to be around 0.5 in/hr. The band will keep fairly good forward progress through the morning hours, so the heavier snow will be brief in any one spot, generally 15-30 minutes. The band also looks to become less defined as it pushes eastward, especially as it moves into the Greens. Still, anticipate it'll make for hazardous travel. Roads are already snow covered in many areas, and visibility will drop sharply as the band moves through. Winds will quickly intensify with and/or just after the band moves through (more on that in Key Message 2 discussion below), which will easily blow the dry snow around, especially in open areas. The band should arrive here in the Champlain Valley 5-7 am, then exit into NH between 10 am and noon. Snow will gradually wind down through the afternoon hours as much drier air rushes in behind the front. Flow turns to the NW, so snow should trend toward upslope snow showers in the northern Adirondacks and Greens through the afternoon hours, eventually ending this evening. Snowfall amounts are still anticipated to be a general 1 to 3 inches, with 2 to 4 inches in the higher terrain and in some of the favored upslope areas. Even the eastern side of the Champlain Valley could end up on the higher side; flow will be highly blocked with Froude numbers less than 0.20 much of today.

KEY MESSAGE 2: The arctic front is crossing into the St Lawrence Valley early this morning, with much colder following along in its wake. Per the NY Mesonet, note that Hammond's temperature dropped 8 degrees in 20-30 minutes with the frontal passage, but more notably, winds have increased substantially; they are currently NW 15-20 mph gusting to nearly 30 mph. This trend will continue to spread eastward through the rest of this morning, with wind chills quickly dropping to around -20F by daybreak across northern NY. Meanwhile, areas from the Champlain Valley eastward will also see sharply dropping temperatures and wind chills plummeting below zero through the daylight hours today. The brisk northwest winds will continue overnight tonight, ushering in a dangerously cold airmass. Ambient temperatures will drop into the teens below zero across the Adirondacks and St Lawrence Valley, while areas from the Champlain Valley eastward will mainly stay in the negative single digits. Hence still anticipate the coldest wind chills of 20 to 40F below zero to stay across northern NY, with 15 to 25F below zero further east. This cold will persist through the morning hours on Sunday. It should be noted that guidance isn't going quite as drastically cold for Sunday's highs, but still anticipate highs will only top out in the positive single digits. This with subsiding winds will help wind chills "improve" to -5 to -15F in most areas during the afternoon hours on Sunday. With all this in mind, the current cold headlines still seem reasonable and therefore no changes have been made. An Extreme Cold Warning covers the Adirondacks and St Lawrence Valley from 7 am today to 1 pm Sunday, with the Champlain Valley eastward under a Cold Weather Advisory from 6 pm this evening to 1 pm Sunday. Regardless of the headlines though, it's going to be dangerously cold areawide today, tonight, and through much of Sunday. Anyone with outdoor plans should consider altering and/or delaying outdoor activities this weekend. 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.

High pressure will build into the region later Sunday into Sunday night before shifting east on Monday. Winds will continue to slacken overnight, making for better radiational cooling conditions. However, some model guidance continues to show there could be some lingering low cloud cover, especially over the higher terrain. This could potentially limit cooling potential. Have continued to blend in some colder guidance for Sunday night, with lows generally -5 to - 15F. With mainly light winds, wind chill values will be close to Advisory criteria (-20F), so additional cold headlines might be needed.

KEY MESSAGE 3: Still limited run to run consistency with a large spread in guidance with regards to pattern evolution and track of synoptic scale systems. The general idea shows warm air advection lift/moisture impacting our cwa mid week with a period of light snow shower activity. Given primary sfc low pres tracking to our northwest, expect some trrn shadowing here in the CPV with temps climbing close to freezing. GFS conts to show lingering upslope snow showers thru most of the week, while ECMWF is building 1030mb high pres into our fa with cool nights and seasonable daytime highs. This would suppress the storm track and best moisture to our south thru most of the upcoming week. Until better agreement is reached in our guidance, have continued with highest pops acrs northern NY into the mountains of central/northern VT, with lower pops in the CT River Valley and parts of the CPV. Highs generally warm into the mid 20s to mid 30s with lows in the teens. Much cooler lows would be possible if high pres with clear skies and light winds were to develop per ECMWF solution, especially toward late week. Best potential for light snow accumulation wl be acrs the higher trrn of the dacks and central/northern Greens.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...Snow showers continue across our taf sites this morning with mostly IFR/LIFR conditions with developing northwest winds 10 to 20 knots. The greatest potential for periods of LIFR vis and MVFR/IFR cigs will be on the east side of the Champlain Valley (BTV/RUT) thru 16z associated with blocked flow. Mostly IFR vis with MVFR cigs prevail at SLK/EFK and MPV with improving conditions mostly likely to MVFR at MSS by 15z. As flow continues from the northwest, expect PBG to improve toward MVFR/VFR conditions btwn 15z-18z today. Gusty northwest winds will create areas of blowing and drifting snow, especially at MPV/BTV/MSS and RUT thru early this aftn. Winds slowly decrease between 4 and 8 knots by evening. As drier air develops conditions should improve to a combination of VFR valleys and MVFR mountain sites by 03z this evening with trends toward VFR by 06z.

Outlook...

Sunday: VFR. NO SIG WX. 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.

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.