Marine Weather and Tide Forecast for Barre, VT

KEY MESSAGES
As of 215 PM EST Saturday...
1. Bitterly cold temperatures and wind chills of -15F to -25F expected tonight across parts of the area, increasing the risk of hypothermia and frostbite.

2. A long duration and widespread moderate to locally heavy 8 to 16 inch snowfall is expected late Sunday through Monday, making for hazardous travel, especially the commutes on Monday.

3. Below normal temperatures are expected to continue across the region next week, with periods of isolated to scattered snow showers possible.

DISCUSSION
As of 215 PM EST Saturday...

.KEY MESSAGE 1: Bitterly cold temperatures and wind chills of -15F to -25F expected tonight across parts of the area, increasing the risk of hypothermia and frostbite.

A 1040mb high pres is progged to be centered over the NEK of VT at 06z tonight, which wl provide cwa with ideal radiational cooling conditions with light winds and clear skies. After 06z mid/upper lvl clouds should overspread the region from southwest to northeast in advance of our approaching winter storm. Given temps have struggled to reach 0F in many spots with dwpts in the -10F to -20F range, feel temps wl drop like a rock once the sunsets this evening. I have tried my best to capture the rate of temp fall, thinking -15F to near -25F for NEK/SLK areas with -5F to -15F elsewhere for lows. The cold weather advisory is for the combination of temps and wind chills between -15F and -25f acrs parts of our cwa, which can increase the risk of hypothermia and frostbite.

.KEY MESSAGE 2: A long duration and widespread moderate to locally heavy 8 to 16 inch snowfall is expected late Sunday through Monday, making for hazardous travel, especially the commutes on Monday.

Overall fcst remains on track for a long duration and widespread moderate to locally heavy snowfall acrs our cwa from late Sunday thru Monday. The challenging aspect is amount of qpf and associated snowfall ratios. Good news it will be an all snow event.

Water vapor shows deep moisture advection from sub-tropical jet moving acrs the central/southern CONUS attm, with potent southern stream s/w energy over the central Baja, while northern energy is dropping south acrs the northern Plains. As potent s/w energy ejects eastward tonight, sfc low pres wl develop over the MS River Valley by Sunday, while 1040mb arctic high pres remains anchored over northern New England. The position of sfc high pres wl help to enhance CAD signature on lee-side of the Appalachians Mtns and produce a double barrel (Miller Type B) low pres structure by late Sunday. The primary sfc low pres wl track from northeast NC to just inside the 40/70 benchmark by 12z Monday, while secondary low pres produces a weak inverted sfc trof like feature acrs our cwa by midday Monday.

HRRR shows a brief 1 to 3 hour window of 1 to 1.5" per hour snowfall rates associated with initial surge of 850mb to 700mb fgen forcing on Sunday night. This area of favorable deep layer synoptic scale ascent with favorable rrq of 250mb jet lifts quickly acrs our cwa on Sunday night, along with increasing pw values toward 0.35". Low level wind profiles do indicate a southeast jet of 25 to 45 knots between 925mb and 850mb, so some downslope shadowing and upslope enhancement on initial surge is likely acrs our cwa. I anticipate a general 2 to 6 inches by Monday morning with some local variability due to trrn.

As additional northern stream s/w energy crosses our cwa btwn 15z- 00z Monday, an inverted sfc trof features develops somewhere from northern NY into central VT. Its this llvl convergence, combined with additional 7h fgen forcing that could produce a localized enhanced area of snowfall on Monday acrs portions of our cwa. My NAM 12KM mesobanding procedure indicates this narrow band of favorable lift/moisture could be stationary for several hour midday Monday.
Its extremely difficult to pin point the exact placement and movement, but many of the high res guidance shows this potential acrs the central CPV, including the Milton to Burlington to Hinesburg areas. Furthermore, as wind slowly shift from northeast to northerly, the llvl convergence with strong blocked flow (froude <0.50) develops, helping to enhance potential snowfall amounts locally. Its interesting to note the NBM mean 48 hour snowfall for BTV is 17 inches with 25th of 16" and 75" of 20 inches, while 1V4 mean is 12", 11" and 14" respectively. Given the primary sfc low pres track, feel SLV may have difficulties reaching warning level snow criteria, as NBM shows mean values in the 5-8" range.

Snow ratios are challenging with this event, given the extremely cold air mass, which holds limited amounts of moisture. Pw values surge to near 0.40" on Sunday night associated with waa lift/moisture, but drop back into the 0.15" to 0.25" range by Monday, as northern stream dynamics move acrs our region. Does the amount of moisture and intervals of better lift/dynamics impact snow ratios at time during this event, probably. I used an average of 18/20 to 1 but think this maybe high at times. I think we may see some smaller flakes initially before complete saturation of the column occurs and again on Monday morning before better energy aloft arrives. I tried to integrate that into my final snowfall amounts, which ranges from 6-8" SLV, 8-12" northern Dacks into NEK of VT, and 12 to 16" in the CPV and central/southern VT. I would not be surprised within the local mesoscale band/inverted trof axis isolated amounts 16" to 20" by 06z Tuesday. Just too difficult to determine location attm. Thinking storm total qpf ranges from 0.40" SLV to locally 0.75" to 0.85" southern Green Mtns.

Moisture final decreases on Monday night with lingering snow showers associated with upslope flow and caa prevailing over the northern/central Greens. However, moisture is quickly decreasing after 06z, so probably just flurries toward Tues morning. Temps remain cold throughout the event with highs only in the single digits and teens and lows remaining steady.

.KEY MESSAGE 3: Below normal temperatures are expected to continue across the region next week, with periods of isolated to scattered snow showers possible.

In the wake of the winter storm exiting the region Monday night, a cold pattern looks to set up with below normal temperatures expected for most of the week and occasional chances for snow showers. Daytime highs look to climb into the single digits and teens, compared to climatological normals in the 20s. Overnight lows look to generally be in the single digits above and below zero, with Wednesday night into Thursday looking to be the coldest. Some periods of showers will be possible throughout the week with an upper low across Quebec, and while exact timing is uncertain, any snow amounts look to be fairly light during this time frame with very little moisture. The best chances for showers will be along the favored upslope areas,as well as across St. Lawrence County and portions of the Adirondacks due to some enhancement off Lake Ontario, but accumulations are expected to be light.

AVIATION /19Z SATURDAY THROUGH THURSDAY/
Through 18Z Sunday...Strong high pressure will keep flight weather conditions VFR through this forecast period. Winds will begin westerly to northwesterly generally less than 10kts except for some gusts around 15kts continuing at MPV through 21Z.
Light winds follow overnight through Sunday. Clouds increasing late in the period with potential for snow showers 16-18Z for MSS/SLK/RUT/VSF. Much more impactful weather will follow this forecast period as a significant winter storm moves into the region.

Outlook...

Sunday Night: MVFR and IFR. Definite SN.
Monday: Mainly MVFR and IFR, with local VFR possible. Definite SN.
Monday Night: VFR. Chance SN.
Tuesday: Mainly VFR, with local MVFR possible. Slight chance SHSN.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: 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...Cold Weather Advisory until 7 AM EST Sunday for VTZ003-004- 006>008-010-016>020.
Winter Storm Warning from 1 PM Sunday to 1 AM EST Tuesday for VTZ001>011-016>021.
NY...Cold Weather Advisory until 7 AM EST Sunday for NYZ026-027- 029>031-034.
Winter Storm Warning from 1 PM Sunday to 1 AM EST Tuesday for NYZ026>031-034-035-087.