531
FXUS61 KBTV 262338
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
638 PM EST Tue Nov 26 2024

.SYNOPSIS...
Some lake effect snow will develop late today into Wednesday,
bringing some light accumulations to the Adirondacks. A
potentially more significant winter storm may follow for the
Thanksgiving holiday with potential for accumulating snow and
hazardous travel conditions extending into Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 528 PM EST Tuesday...Steady precipitation has exited to
our east this evening, though isolated to scattered showers
continue across mainly northern areas. Showers should wane over
the next few hours. However, a lake effect band is becoming
organized off of Lake Ontario, and this will become fairly
persistent overnight, focusing across southern St Lawrence
County east/northeastward toward southern Clinton County. Some
of this activity could occasionally drift into the Champlain
Valley and northern VT, but the bulk will occur in the
Adirondacks. Temperatures are currently warm enough for mainly
rain, except for areas east of the Greens where temperatures
close to freezing are allowing for some snow and perhaps even a
little light rain to fall. Expect this to become all snow early
Wednesday morning as temperatures will fall into the mid 20s to
low 30s. Snowfall totals of an inch or two are expected in
northern NY under the band, with 2-4 inches over the higher
terrain. Elsewhere, snow accumulations will be under an inch.
Have made tweaks to temps, PoPs, and weather to match the latest
trends, but overall the forecast remains in good shape.

Previous discussion...Synoptically forced rain and
freezing rain will continue to move eastward and out of our
region this evening. Attention will then turn to potential for
some lake effect snow ahead of next possibly impactful system on
Thursday. Our flow will become westerly overnight with a large
surface low pressure circulation over Canada which will remain
through early Thursday. This will lead to initiation of a lake
enhanced snow band off of Lake Ontario that will wave across
portions of northern New York from St Lawrence County into the
central Adirondacks. This band will likely sag southward early
Wednesday before oscillating northward and dissipating. A
dusting to two inches are most likely, but up to 4 inches is
possible where the center of the band lingers longest - the
center of the band is currently projected south of St Lawrence
County. Some eastward extension of the band and upsloping on the
western slopes of the Greens is possible, but totals look to be
less than 1 inch through Wednesday. Wednesday night will start
quiet with relative high pressure over the North Country.
However, clouds increase south to north as low pressure tracks
south of the North Country. More widespread precipitation will
move into the area during the day Thursday. Daytime temperatures
will be near normal Wednesday and a bit warmer than normal both
tonight and Wednesday night.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 320 PM EST Tuesday...

Key Messages:

- Rain and snow are expected on Thursday (Thanksgiving Day).
  Higher elevations will see plowable snow, while lower
  elevations and valleys will see predominantly rain or a
  rain/snow mix.

- Two potential solutions remain possible. Our forecast
  trends toward the less impactful solution, however a stronger
  system with potential heavy snow bands still cannot be ruled
  out.

A coastal low will develop Thursday under an open wave aloft,
tracking near or inside of 40N 70W (Benchmark). The quick-moving
system will bring a shot of rain and snow to our forecast area
during the day on Thanksgiving. There remain two camps of models
and thus two potential scenarios. The forecast we continue to
favor is the GFS/CMC/NAM consensus with a fast moving system
with 0- 6 inches of snow for our area. The lack of closed low
aloft and lack of blocking downstream will allow the coastal low
to quickly zip northeastward. The majority of the QPF will come
during the day on Thursday, when temperatures will be warming
to near or above freezing. Predominant precipitation type in
elevations below 1000 ft will be rain or a rain/snow mix, with
minimal accumulations. Elevations between 1000 and 1500 feet
will see accumulating snow in the 1-3 inch range, and elevations
above 1500 feet can expect 3-6 inches. Snow that falls during
the day will be have snow ratios around 8:1, which will support
a wetter snow consistency.

While our official forecast is as described above, there is
still a second potential scenario that the ECMWF continues to
depict, which would be more impactful to our area. This would
feature a deeper surface low tracking slightly further inland
(near Boston) with increased wrap around moisture into southern
Vermont. Under this scenario, precipitation rates would be
moderate to heavy at times over southern Vermont, and the
northwestern periphery of the system would also be shifted north
and west. This would also be a more favourable setup for banded
snowfall northwest of the low center, potentially pivoting over
southern Vermont. While overall this continues to be an outlier
of a solution, the deterministic ECMWF has been remarkably
consistent. In addition, the ECENS show very low spread in low
track. All said and done, we cannot completely discount this
solution, which would bring snowfall in the 6-12+ inch range to
southern Vermont, with banded locally heavier snowfall. Stay
tuned as we continue to fine tune the details.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 320 PM EST Tuesday...The quick moving system will exit
Thursday night into Friday morning, followed by generally
unsettled weather into the weekend as we remain within broad,
cyclonic flow. The main regional weather of concern this weekend
will be lake effect snow bands off the Great Lakes, which will
only impact our forecast zones minimally, with greater impacts
expected south. An initial lake effect snow band will setup east
of Lake Ontario during the day on Friday. The eastern fringes
of the band will bring some lake effect snow/rain showers to
portions of northern NY, mainly southern Saint Lawrence County,
Friday through Saturday night. Sunday into Monday, the band will
shift south of our area, but we may continue to see some light
showers on the outer fringes of the band. In addition, multiple
shortwaves rotating around the base of the longwave trough will
occasionally reinvigorate showers. Temperatures will undergo a
cooling trend from the weekend into early next week, with highs
expected in the upper 30s to low 40s late this week, and only
into the 20s to low 30s by early next week.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thurssday...Westerly cyclonic flow will dominate
this period with this cooling flow across the relatively mild
Great Lakes. This will bring clouds and rain/snow showers
immediately downstream with moisture in the form of clouds and
isold to sct -shsn/-shsa in portions opf the Adirondacks.

Largely Sct clouds in the valleys with VFR and possible MVFR
ceilings in the upslope mountain TAF sites. West winds 5-10 with
possible gusts 15-18 mph will continue through the period as
well.


Outlook...

Wednesday Night: VFR. Slight chance SN.
Thanksgiving Day: Mainly MVFR, with local IFR possible. Likely
RA, Chance SN.
Thursday Night: Mainly MVFR, with areas IFR possible. Likely RA,
Chance SN.
Friday: Mainly VFR, with local MVFR possible. Slight chance SHRA.
Friday Night: VFR. Chance SHSN.
Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Slight chance SHSN.
Saturday Night: Mainly VFR, with areas MVFR possible. Chance
SHSN.
Sunday: Mainly VFR, with areas MVFR possible. Slight chance SHSN.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Neiles
NEAR TERM...Hastings/Neiles
SHORT TERM...Duell
LONG TERM...Duell
AVIATION...SLW