351
FXUS61 KBTV 202327
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
627 PM EST Tue Jan 20 2026
.WHAT HAS CHANGED...
As of 206 PM EST Tuesday...No significant changes were made to
the forecast.
&&
.KEY MESSAGES...
As of 206 PM EST Tuesday...
1. Light to localized moderate snowfall associated with rounds
of snow showers with possible snow squalls, primarily late
Wednesday into Thursday and again on Friday, will produce some
hazardous travel.
2. A significant and dangerously cold arctic outbreak is
expected late week into the upcoming weekend with wind chill
values 20 to 40 degrees below zero possible.
&&
.DISCUSSION...
As of 144 PM EST Tuesday...
.KEY MESSAGE 1:
A series of fronts, including a warm front tomorrow evening, a cold
front on Thursday, and an Arctic boundary on Friday, will support
snow showers through the rest of the week.
This afternoon, satellite imagery shows cloud streets along with a
corridor of cooler cloud tops where light snow showers have been
more numerous, downwind of an intense lake band in the Tug Hill
plateau and also in far northwestern Vermont which also is seeing
Lake Champlain and valley convergence effects. To some degree
diurnally-driven instability is driving this activity so there will
be some diminishing trends tonight, especially as the lake band
retracts and shifts northward, such that snow returns to at least
southern portions of St. Lawrence County overnight. Otherwise, the
next round of light snowfall, which will be more widespread given
the large scale forcing features significant 850 millibar warm
air advection, will be in the form of up to a few hours of
steady snow. Snowfall rates are most likely to be only up to
0.5"/hour, with greatest chances to approach 1"/hour rates and
potentially impacting the Wednesday evening commute, in northern
New York especially western and southern areas. Strong cloud
layer winds (in the 40 to 60 MPH range) would point to
fracturing of snow dendrites and reducing chances for seeing
particularly high snow ratios despite otherwise favorable
conditions. Current forecast in the 16 to 18:1 range might be a
little high, but with uncertainties and generally low
QPF/precipitation amounts think they are reasonable. Total
snowfall through Wednesday night is mainly 0.5" to 2", except 2"
to locally 4" in the aforementioned portions of northern New
York where the heavier snowfall is favored.
For Thursday, model guidance remains consistent depicting the snow
squall parameter increasing into the moderately high range due to
instability driven by height falls ahead of an approaching cold
front. Compared to the Monday event, the system looks a bit weaker
in terms of winds/pressure rises and falls; earlier timing helps
achieve greater surface instability which may compensate, leading to
more snow shower activity but perhaps less intense. Since there will
not a sharp low level thermal boundary or convergence (note winds
will remain southwesterly for most locations Thursday night), it
still looks like scattered activity, so it is hard to provide
specific timing/location information. Generally A potent
southwesterly jet, does reduce chances for appreciable snow shower
activity in portions of the Champlain Valley downwind of the
Adirondack high peaks, but this shadowing effect will be fairly
localized and not as pronounced as during the Wednesday evening
snow. Farther south, west-southwest flow will support more lake
effect/hybrid snow shower activity that will probably necessitate
another round of Winter Weather Advisories as heavier snow amounts
in the 4 to 7 inch range currently are expected in total for
Thursday through Thursday night. An intense band off of Lake Ontario
is once again expected to develop behind this cold front Thursday
night with favorable fetch and cold air advection, and for at least
several hours will waffle into southern St. Lawrence County before
sinking southward per model consensus and climatology.
Arctic cold frnt drops acrs our cwa on Friday with scattered snow
showers and embedded snow squalls possible. The combination of lake
moisture/instability and digging 5h s/w wl help to enhance snow
shower activity along the boundary on Friday. Given multiple
boundaries and cold air bleeding into our region, several rounds of
snow showers are possible on Friday, which could have local impacts
on travel. Soundings indicate the depth of moisture is rather
limited, so areal coverage of snow showers wl be scattered.
.KEY MESSAGE 2: Forecaster confidence continues to increase for
a significant and dangerous arctic outbreak this weekend.
Extreme cold warnings and cold weather advisories will be needed
for the forecast area late Friday into Sunday. Friday night
into Saturday will be an advection type cold with dangerously
cold wind chill values in the 20 to 40 degrees below zero with
radiational cold on Sat night into Sunday.
The core of the coldest 925mb to 850mb temps with sub 490 thickness
values are directly overhead btwn 03z and 12z Saturday. Progged
850mb temps range btwn -28C and -32C, while 925mb temps are in the
-25C to -30C, which supports lows -5F to -20F with wind chills on
Sat morning between -20F and -40F, coldest in the mountains. Highs
on Saturday will struggle to reach 0F in the CPV with -5F to -10F in
the mountain valleys. A progged 1040mb sfc high pres is expected to
be centered over SLK at 06z Sunday, which should result in clear
skies and light winds, with lows ranging from -20F to -30F SLK/NEK
to -10F to -20F elsewhere. As always, the challenging part for Sat
night-Sunday morning lows will be potential for high clouds in the
westerly flow aloft and impacts on temps. For now have trended
toward the NBM 50th percentile which has a low of -25F at SLK/Island
Pond, -23F at MSS, and around -10F in the BTV area.
Have noted a slight shift northward for light snow late Sunday into
early next week associated with southern stream system. I have my
doubts if moisture can overcome 1040mb high pres anchored over
northern New England to saturate the low levels enough to produce
light snow, given progged track of sfc low pres well south of our
cwa. For now I have increased pops into the schc/chc range, with
plenty of time to shift northward if needed. Thinking most precip is
virga, as low levels wl be very dry given prevailing north/northeast
flow.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thursday...Convective snow showers are waning at the
tip of a lake effect snow band, and so conditions are VFR across
all terminals with patches of 3500-6000 ft agl ceilings. Strip
of lake effect downwind of Lake Ontario will amble north towards
KSLK about 03z-06z, and perhaps KMSS about 07z-10z, but the
latter has drier low-level conditions. Noted 2SM -SN in a TEMPO
for KSLK. 2000ft winds across northern New York will increase to
35 to 40 knots as lake effect begins to shift, and this will
result in LLWS at KSLK and KMSS through about 08z-11z. Otherwise,
quiet conditions are expected with west-southwest winds
gradually turning southerly. High clouds move in from the south
beyond 12z and winds will begin to increase over the course of
the day up to 8 to 15 knots sustained and gusts 16 to 25 knots.
Virga will be likely on radar along a warm front due to low
level dry air. The earliest arrival of snow for most will be
about 20z-23z, and so PROB30s are noted for light snow.
Additional snow and increasing south winds at 2000 ft agl will
move in near or after 00z Thursday.
Outlook...
Wednesday Night: Mainly VFR, with areas MVFR possible. Windy with
gusts to 30 kt. Chance SHSN.
Thursday: VFR. Scattered SHSN.
Thursday Night: VFR. Slight chance SN.
Friday: VFR. Slight chance SHSN.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Slight chance SHSN.
&&
.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...None.
NY...None.
&&
$$
DISCUSSION...Kutikoff/Taber
AVIATION...Haynes
CLIMATE...NWS BTV
EQUIPMENT...NWS BTV
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