000
FXUS61 KBTV 102323
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
623 PM EST Sun Dec 10 2023

.SYNOPSIS...
A strong storm will impact the region tonight through Monday,
bringing rain this evening changing to a heavy wet snowfall
overnight. Travel will become very difficult, especially after
midnight into Monday, including the Monday morning commute.
Scattered to numerous power outages are possible, with the heaviest
snowfall occurring over the central and northern Green Mountains of
Vermont. Quieter weather with near normal temperatures return for
midweek.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 611 PM EST Sunday...Things remain on track this evening as
we wait for the precipitation change over. Note that KSLK is now
reporting unknown precip at 36F, so expect we`ll start to see
snow shortly. Overall, the forecast remains on track for now, so
no changes were needed with this update.

Previous discussion...No changes to the winter storm
warnings/advisory or flood watch with this package. Overall system
remains on track with just some minor trends noted in the 12z
guidance, which combined with integrating our latest high resolution
data has resulted in a sharpening of the snowfall gradient acrs our
region from the valleys to mtns.

Scattered to numerous power outages possible, especially below 1500
feet, along with a very hazardous Monday morning commute with
moderate to heavy snow falling and sfc vis below 1/2sm at times.

A challenging fcst continues especially with regards to snowfall
fcst and associated sharp elevational depend gradient, given
marginal temps here in the valleys, but mountains will do very well
again.

Water vapor highlights deep warm conveyor belt of rich moisture
advecting acrs the eastern CONUS, while potent s/w energy is
rounding the trof base over the southern Appalachian Mtns. This
energy, combined with rrq quad of 25h jet of 160 knots, wl enhanced
sfc low pres over eastern NC by this evening. Its this energy moving
directly overhead on Monday morning, that results in a period of
moderate to heavy snowfall for most of us. Meanwhile, sfc low pres
is progged to interact with a sharpening thermal boundary moving
acrs northern NY/central PA attm, while deepening over SNE on Monday
morning.

The 12z guidance has trended slightly eastward with the sfc low pres
track along with deepening the associated area of low pres a bit
later, which results in a tightening of qpf and a slight shift in
the heaviest axis of precip. However, dynamics with this system are
very strong and moisture content is near climo max, based on ALY 12z
sounding of 0.90" pw value, which is near the daily max of the day
of 1.0". Also, another minor trend in guidance has been for the
cooler air aloft to advect into our region quicker, which is
supported by LAPS/RAP analysis of the 0C 850mb isotherm already in
the SLV. Have timing of rain changing to snow occurring around 00Z
dacks and btwn 00z-02z northern Greens with snow levels lowering
thru the overnight hours.

As potent s/w energy over the se CONUS moves directly overhead,
combined with axis of strong 850-500mb fgen forcing placed from se
to nw acrs our cwa, we are expecting a period of moderate to heavy
snowfall, with rates exceeding 1 inch likely. The timing looks to be
btwn 07z and 15z Monday, based on progged s/w timing and jet
dynamics. This should quickly cool column and allow a heavy wet
snowfall with vis btwn 1/4 and 1/2sm to occur for several hours on
Monday morning, acrs most of our fa. The duration of the very strong
lift/dynamics is relatively short, as flow is progressive, so
thinking window of heaviest snowfall accumulation is 3 to 6 hours
from south to north.

Snowfall continues to be very tricky, especially locally in the CPV,
given the warm Lake Champlain water, 2m temps hovering near 32/33F
for the entire event, warm ground temps, which results in lower
ratios and challenging accumulations rates. Have lowered some
accumulations acrs the CPV to highlight the extremely sharp snowfall
gradient expected from several slushy inches near the water to 5
to 8 inches at BTV airport to 7 to 14 inches Underhill/Jericho.
Elsewhere, the western extent of the heaviest precip over the
dacks is tricky, but given higher ratios, especially over the
trrn, lower qpf amounts should result in reaching low end
warning criteria. The SLV struggles to see much snow
accumulation given the warm bl temps and lack of strong
dynamical forcing, but wl keep advisory going for now.
Central/northern Greens still look to be the bullseye of
heaviest snowfall totals of 12 to 18 inches, especially above
1500 feet, with lighter amounts as you travel toward the
immediate CT River Valley. Lows tonight range from the mid 20s
summits to mid 30s warmest valleys.

As system quickly races off toward eastern Canada on Monday aftn,
expect areal coverage of precip to become trrn focused over the
northern Dacks and central/northern Greens aft 18z. The lighter
precip rates here in the valleys with temps warmer a degree or two,
should result in a mix of rain/snow showers with improving road
conditions by the evening commute. Given the slight shift in track,
the backside wind component is not as strong for Monday aftn, with
localized gusts mainly in the 20 to 30 mph. Snow showers taper off
in the mtns on Monday night with cooling temps in the mid teens to
mid 20s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 326 PM EST Sunday...A weak ridge of high pressure will quickly
transit over our CWA during the day on Tuesday. Outside of some
possible lake effect snow in the Saint Lawrence Valley, we won`t see
daytime precipitation. The story changes quickly as the ridge moves
to our east and a cold front comes into Northern New York and
Vermont in the overnight hours. Widespread snowfall totals will
remain less than an inch, but the front will provide the
thermodynamics necessary to generate a few heavy snow bands. The
latest model runs have backed down the CAPE making a full blown
squall less likely.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 326 PM EST Sunday...An upper level low off the Canadian
maritimes will set the plate on Wednesday for a little more snow
accumulation along the upslope areas. Once again, the conditions
only favor an inch or so. Wednesday night and Thursday will remain
quiet as we transition between fronts. The final system of this
forecast period will begins to take shape Friday as another cold
front sweeps through the longwave trough to our north and east. A
low pressure system forming in the midwest will ensure a tighter
pressure gradient and allow for some more nickel and dime
accumulation with a similar setup to Tuesday`s.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
Through 00Z Monday...After some brief MVFR/VFR early in the TAF
period, overall expect IFR/LIFR to prevail through much of the
next 24 hours as widespread rain transitions to snow. Snow will
be moderate to heavy at times, generally 06z-14z, and
visibilities 1/2sm. Some improvement with lessening snowfall
rates after 14z, mainly at valley locations. Ceilings will lower
to below 1000 ft at all terminals by 03z, and remain so through
at least 18z Monday, may lift to 1500 ft at valley locations by
20z.

Most sites currently seeing north winds around 5 kt, with
KMSS/KSLK/KRUT reporting southwest/southeast winds,
respectively. All terminals to turn to the north/northwest by
03z, and remain so through the remainder of the forecast period.
Winds will remain fairly light from the northwest through the
overnight and morning hours but become gusty at 20 to 25 knots
by 16Z Monday.

Outlook...

Monday Night: Mainly VFR, with local MVFR possible. Chance SHSN.
Tuesday: VFR. NO SIG WX.
Tuesday Night: Mainly VFR, with local MVFR possible. Chance SN,
Chance FZRA.
Wednesday: VFR. Slight chance SN.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.

&&

.HYDROLOGY...
Sunday 1238 PM UPDATE...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 8.0 feet (Minor Flood Stage) Monday. The
Flood Watch remains in effect for Rutland and Windsor Counties
in Vermont through Monday afternoon where precipitation is
expected to stay as rain longer and combined with snow melt
could cause minor issues.

&&

.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 this evening to 7 PM EST
     Monday for VTZ021.
     Winter Storm Warning from 10 PM this evening to 7 PM EST
     Monday for VTZ001>011-016>020.
     Flood Watch through Monday afternoon for VTZ011-019>021.
NY...Winter Weather Advisory from 10 PM this evening to 7 PM EST
     Monday for NYZ026-087.
     Winter Storm Warning from 10 PM this evening to 7 PM EST
     Monday for NYZ027>031-034-035.

&&

$$
SYNOPSIS...Taber
NEAR TERM...Hastings/Taber
SHORT TERM...Langbauer
LONG TERM...Langbauer
AVIATION...Clay/Hastings
HYDROLOGY...Chai
CLIMATE...Team BTV
EQUIPMENT...Team BTV