NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS61 KBTV 092343 AFDBTV

Area Forecast Discussion National Weather Service Burlington VT 643 PM EST Sat Dec 9 2023

SYNOPSIS
A strong storm will impact the region Sunday through Monday, bringing initially rain that will transition to a heavy wet snowfall. Travel will be very difficult, especially Sunday night into Monday, including the Monday morning commute. Scattered to widespread power outages are expected. In addition, rivers are expected to rise sharply Sunday night into Monday but the threat for flooding is decreasing. Quieter weather returns for midweek.

NEAR TERM /THROUGH SUNDAY/
As of 634 PM EST Saturday...There are some light returns on radar this evening, but based on observations, none of this seems to be reaching the ground. The St. Lawrence Valley has its standard terrain driven temperature spread with Massena at 34 on one end, and Edwards at 54 on the other. Massaged Massena temperatures for their terrain driven flow and otherwise made small tweaks to PoPs with the remainder of the forecast in great shape. Have a great night!

Previous Discussion...
The period starts out relatively quiet with just a few light passing showers acrs northern NY associated with deep southerly flow and continued warm air/moisture advection. Better chances for additional showers arrive toward 12z acrs the SLV associated with an embedded s/w in the flow aloft, along with axis of enhanced mid lvl moisture. Rainfall wl be a tenth to two tenths of an inch, mainly acrs northern NY thru 12z Sunday. Temps overnight are challenging and will be wind/trrn driven. Coolest values northern SLV near KMSS and eastern side of the Greens, with lows upper 20s to mid 30s, while southerly winds prevail in the CPV and parts of northern NY. For Sunday, the first wave of rain moves from southwest to northeast acrs our cwa, with some trrn influence shadowing possible acrs the CPV, associated with 850mb winds of 35 to 50 knots. Winds and associated mixing profiles are tricky, but expect localized gusts 25 to 35 mph parts of northern Dacks, and central/northern CPV. Additional rainfall generally another 0.10 to 0.25 with highest values over the Dacks into northern VT mtns. Progged 925mb temps are very warm on Sunday with values btwn 8-10C, supporting highs l/m 50s CPV/parts of the SLV, while mid/upper 40s prevail elsewhere.
Anticipating some snow melt on Sunday acrs the Dacks and central/northern and eastern VT trrn, which wl slowly drain into the area waterways.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
As of 342 PM EST Saturday...Upgraded winter storm watch to warning acrs most of VT, where confidence is highest for warning criteria snowfall, while maintained the watch for northern NY given the slight eastward shift in the 12z guidance. Did issue advisories for the CT River Valley near VSF/Eastern Essex NY, and southern SLV, after coordination with neighbors.

Very little change has occurred with our storm total snowfall thinking with 4 to 10 inches eastern CPV/portions of the northern Dacks and Valleys of the NEK to localized 10 to 20 inches central/northern Green Mtns of VT, while 2 to 6 inches SLV and lower CT River Valley.

Also, based on slight shift eastward and cooler thermal profiles have removed northern/central area for flood watch, as latest forecast from River Forecast Center is significantly lower.

Scattered to widespread power outages are becoming increasingly more likely, especially for the Champlain Valley with isolated to scattered outages possible elsewhere. Unlike our previous couple events, thinking the greatest potential for outages will be in the valleys, as drier/higher snow ratios should limit outages acrs the higher trrn of the dacks and central/northern Green Mtns in VT. Given the complex thermal profiles, once again a strong elevational snowfall gradient is anticipated. For example snowfall near the warmer Lake Champlain waters will be a slushy couple of inches, while near the BTV airport 4 to 8 inches is likely, to 6 to 10 inches in Williston/Essex to 10 to 16 inches Underhill/Bolton base. Similar type scenario plays out acrs the CT River Valley from VSF to 1v4, with much higher amounts in the trrn toward Brookfield to Walden/Burke Mtn.

Little has changed with regards to large scale synoptic features associated with upcoming system, with just minor shifts in the sfc low pres evolution and track. The idea of deep full latitude trof crntly located over the MS River Valley wl cont to progress eastward, while a sharpening thermal boundary develops along the eastern Seaboard. As potent s/w energy crntly responsible for convection over the southern Appalachian Mtns moves eastward overnight, sfc low pres wl consolidate acrs eastern NC by Sunday evening. This sfc low pres wl track along the tightening thermal boundary from eastern NC to southern New England by 12z Monday, while deepening to sub 985mb acrs central/eastern Maine on Monday aftn. Helping with sfc low intensification wl be a strong rrq of the polar jet of 160 to 180 knots at 250mb lifting acrs southern Canada, while the sub-tropical jet is rounding the mid/upper lvl trof base.
In addition, plenty of deep layer moisture is advecting our way ahead of trof, as pw values surge above 1.0", which is 3 to 4 STD above normal. These ingredients combined with favorable 850 to 700mb fgen axis pivoting acrs central VT, supports the idea of moderate to heavy precip, especially CPV and points eastward. Still some uncertainty on back edge of system acrs northern NY, therefore watch remains in place for the potential of 7 inches or more.

Thermal profiles continue to be challenging, especially valleys with 2m temps hovering either side of 32F. Have integrated a combination of NAM 3KM and NBM for hourly temps, which highlights this thinking of near freezing valleys, while temps drop into the 20s mid/upper lvl slopes of the dacks/northern and central Greens. Snow ratios are tricky, especially as cooling occurs aloft but 2m/bl temps stay near freezing during the heaviest precip in the valleys, so have tapered back ratio's into the 6/8 to 1 valleys, while starting at 8/10 to 1, but increasing to 14 to 18/1 for the mid/upper slopes, especially Monday aftn.

The Monday morning commute is looking especially challenging with heavy snowfall and poor visibilities acrs most of the cwa. Given meso-banding potential, expect a band of moderate to heavy snowfall with hourly snowfall rates exceeding 1 inch likely. The track/placement of band wl continue to evolve over the next 12 to 24 hours. Please plan now for difficult travel and the potential for scattered to numerous power outages associated with this system.
Gusty northwest winds 25 to 35 mph on Monday aftn acrs many of our VT locations, could enhance power outage issues.

Otherwise, some lingering upslope snow showers continue acrs the dacks into the central/northern Greens on Monday night with a few additional inches of fluff possible.

LONG TERM /TUESDAY THROUGH SATURDAY/
As of 342 PM EST Saturday...Main concern through the period, which looks quiet especially compared to the early part of the week, will be potential snow squalls along a polar front Tuesday night into Wednesday. A belt of anomalously strong southwest/west winds aloft per NAEFS output will support good dynamics with the front as it pushes southeastward from Quebec. Timing continues to look roughly between 10 PM and 4 AM; if this holds, potential impacts are greatly lessened since it is mainly a travel concern. Antecedent near- freezing temperatures and strong flow are ingredients that, given a strong front, will support snow squalls even if the snow squall parameter is greater to our north. As we move into the time range of high-res model guidance, more detail will follow about this potential weather hazard. For now, generally have the idea of scattered snow showers Tuesday night, showing greater chances in higher terrain and northern areas. If a more amplified upper level pattern evolves as some model guidance suggests, a scenario with more snow showers on Wednesday is possible. As such, chances (mainly 15 to 40%) of snow showers continue into Wednesday. Looking at ensemble members, the spatial extent of greater snowfall probabilities of at least an inch on Wednesday are consistent with a classic westerly upslope scenario with favorable temperatures and moisture in the low levels. Breezy southwest winds, especially in northern New York, will promote chances for blowing snow on Tuesday, and then west-northwest winds on Wednesday may also be gusty. Will monitor for potential blowing and drifting snow during this period, but at this time looks like a low potential with most likely wind speeds.

We will transition to a warmer pattern on Thursday, with most likely high temperatures still near or a bit below normal. Increased variance in both the high and low temperature is evident in ensemble temperature distribution. This especially true in Vermont during the day, as mixing may limit warming during the day, and then in central and eastern Vermont at night when favorable radiational cooling could allow for another cold night while areas to the west moderate under increasing winds and cloud cover. Then Friday looks like a warmer than normal day with temperatures possibly above freezing areawide, including in the mountains. An anomalous upper level ridge will move overhead while low level temperatures climb further, including above normal 850 millibar values. Depending on the strength of the low level ridge, it will remain dry through the day, but precipitation chances do increase by Friday night as another cold frontal passage becomes more likely. Given the position of a surface high pressure system to our south rather than east, low level flow will be mainly westerly. This setup should limit the amount of moisture/precipitation associated with the system. Even the 90th percentile GFS and CMC ensembles are less than 0.25" of liquid in our region with the Friday night/Saturday front, with the ECMWF under 0.1".

AVIATION /00Z SUNDAY THROUGH THURSDAY/
Through 00Z Monday...Conditions are mainly VFR, though MVFR at KMPV with BKN013 and KMSS with 5 SM visibility. Think the fog at KMSS will be temporary as winds aloft increase, with most locations steady state, except potentially falling in eastern Vermont and noted a TEMPO for 900 ft agl ceilings at KMPV from 03z to 07z. The main story overnight will be increasing winds aloft. VADs already suggest 20 to 30 knot winds at 2000 ft agl, and southwesterly winds at 2000 ft agl are likely to increase to 45 to 55 knots with the fastest winds between about 07z and 15z and then slowly shifting east and weakening. LLWS is mentioned for most at some time for all terminals. A few showers may lift northeast the fast flow, with one batch of showers mainly over northern New York between 07z and 11z, and then more widespread rain moving in from the southwest 15z to 18z. The second batch of rain will correspond with lowering ceilings to 1000-3000 ft agl, especially across Vermont, with visibilities in moderate rain likely 3-6SM and localized IFR ceilings. Beyond 00z Monday, rain will transition to snow.

Outlook...

Sunday Night: MVFR/IFR conditions possible. Definite RA, Definite SN.
Monday: Mainly MVFR, with areas IFR possible. Definite SN.
Monday Night: Mainly VFR, with areas MVFR possible. Chance SHSN.
Tuesday: VFR. Windy with gusts to 30 kt. NO SIG WX.
Tuesday Night: VFR. Windy with gusts to 30 kt. Scattered SHSN.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHSN.
Wednesday Night: VFR. Slight chance SHSN.
Thursday: VFR. NO SIG WX.

HYDROLOGY
Latest forecast thinking...With the colder shift, the flood threat for the upcoming storm system Sunday through Monday has lowered. The latest River Forecast Center forecasts are now cresting all rivers below flood stage with the exception of the Otter Creek at Center Rutland, which is forecast to crest at 8.1 feet (Minor Flood Stage) Tuesday. As a result of the diminishing flood threat, the Flood Watch has been cancelled for northern New York and northern into central Vermont. The Flood Watch remains in effect for Rutland, Windsor, and Orange Counties in Vermont from Sunday afternoon through Monday afternoon.

Overview...A strong storm system will bring widespread 0.5 to 2.5 inches of precipitation Sunday into Monday. Temperatures and dewpoints rising into the 30s to 40s on Sunday will result in some snowmelt that will runoff into area rivers, though models are trending colder with temperatures and consequently the amount of expected snowmelt has decreased. Between 0.2 and 0.6 inches of rainfall are expected Sunday (higher end of the range in southeastern portions of our forecast area and lower end of the range over the Saint Lawrence Valley). The combination of rainfall and snowmelt runoff will lead to river rises Sunday night into Monday, though forecast river crest heights have lowered as models have trended colder.

MARINE
Lake wind advisory continues for south winds 15 to 25 knots with localized gusts up to 30 knots possible on the open waters tonight into Sunday. Waves 2 to 5 feet, especially central/northern portions of the lake.

CLIMATE
Record daily precipitation is possible on both Sunday and Monday. Below are current daily records that may be broken based on the current forecast:

December 10: KBTV: 1.10/1938 KMPV: 0.93/1957 KPBG: 0.69/2004 KMSS: 0.86/1953 KSLK: 0.73/1953

December 11: KBTV: 1.43/1952 KMPV: 0.96/1952 KPBG: 0.81/1952

EQUIPMENT
The Burke Mountain NOAA Weather Radio, WWG-50, broadcasting on a frequency of 162.425 MHz is experiencing technical difficulties and is currently off the air. Technicians have advised that parts are needed to conduct repairs, with an estimated return to service on Tuesday, December 12th.

Please refer to local media and commercial radio for the latest weather information. The following nearby NOAA Weather Radio transmitters that can be used include Mount Ascutney on a frequency of 162.475 MHz and Mount Mansfield broadcasting on a frequency of 162.400 MHZ.

BTV WATCHES/WARNINGS/ADVISORIES
VT...Winter Weather Advisory from 10 PM Sunday to 7 PM EST Monday for VTZ021.
Winter Storm Warning from 10 PM Sunday to 7 PM EST Monday for VTZ001>011-016>020.
Flood Watch from Sunday afternoon through Monday afternoon for VTZ010-011-019>021.
NY...Winter Storm Watch from Sunday evening through Monday evening for NYZ026>031-034.
Winter Weather Advisory from 10 PM Sunday to 7 PM EST Monday for NYZ035-087.

toggle option: (graph/table)

Louiseville
Click for Map
Sat -- 03:38 AM EST     Moonrise
Sat -- 06:47 AM EST     0.81 meters Low Tide
Sat -- 07:22 AM EST     Sunrise
Sat -- 11:14 AM EST     0.84 meters High Tide
Sat -- 01:52 PM EST     Moonset
Sat -- 04:05 PM EST     Sunset
Sat -- 06:27 PM EST     0.82 meters Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Louiseville, Quebec, Tide feet

Sorel
Click for Map
Sat -- 01:43 AM EST     0.88 meters High Tide
Sat -- 03:38 AM EST     Moonrise
Sat -- 04:14 AM EST     0.88 meters Low Tide
Sat -- 05:54 AM EST     0.88 meters High Tide
Sat -- 06:52 AM EST     0.88 meters Low Tide
Sat -- 07:22 AM EST     Sunrise
Sat -- 12:48 PM EST     0.90 meters High Tide
Sat -- 01:53 PM EST     Moonset
Sat -- 04:06 PM EST     Sunset
Sat -- 06:18 PM EST     0.89 meters Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Sorel, Quebec, Tide feet

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Burlington, VT,