Williston, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

947
FXUS61 KBTV 021900
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
200 PM EST Mon Feb 2 2026

.WHAT HAS CHANGED...
As of 151 PM EST Monday...

No significant changes were made this forecast cycle. A few snow
showers are expected in cyclonic flow through Thursday before a
consolidated cold front swings through late week bringing some light
accumulations of snow, gusty winds, and some potential for
dangerously cold wind chill values over the weekend.

&&

.KEY MESSAGES...
As of 151 PM EST Monday...

1. Dangerously cold weather due to combination of gusty winds
and low temperatures is anticipated for much of the weekend. The
cold will gradually ease early next week.

2. Some difficult travel is possible late Friday and Friday
night as snow showers are expected associated with a strong Arctic
cold front.

3. Below average temperatures continue with isolated to
scattered snow showers expected Tuesday through Thursday.

&&

.DISCUSSION...
As of 151 PM EST Monday...

KEY MESSAGE 1: Bottom line: Expect another period with temperatures
below zero and wind chills at times reaching Cold Weather Advisory (-
20) criteria over the weekend. A sharp and strong cold front will
bring another surge of bitter cold air along with gusty northwest
winds into northern New York and Vermont Friday night through
Saturday. There is pretty impressive ensemble agreement on the
strength and track of surface trough with MSLP falling into the 990-
999 millibar range and rapid and strong pressure rises behind the
front. That being said, there are substantial timing differences,
reflected in the 925 millibar temperature spread in the AIGEFS. This
spread peaks early Saturday morning, but overall there is good
agreement that the leading edge of the front pushes through the
region Friday night. As a result, the coldest air mass will settle
into the region during the day on Saturday. These timing differences
have implications for maximum temperatures on Saturday, with
greatest uncertainty as one goes eastward. For instance, the latest
probabilistic temperature data for St. Johnsbury shows a
distribution with a long right tail, such that while the most likely
high is only 6 degrees, there is a reasonable possibility highs
could be in the teens. In that event, would expect temperatures to
be steady or falling during the day while winds remain an important
factor.

NAEFS 700 millibar and 850 millibar ensemble mean temperatures
reflect strong mixing potential with anomalous cold aloft,
especially so over northern New York. As such, blustery northwest
winds will be ongoing through the period making the air feel even
colder. The latest forecast shows minimum wind chills during this
period in the -20 to -29 range across nearly all of northern New
York and most of Vermont except for the Upper Valley. With colder
air expected for Saturday night with winds becoming lighter, even
light wind will support dangerously low wind chills, and aside from
localized spots, the entire region is likely to see wind chills
reaching Cold Weather Advisory criteria. The ECMWF-Extreme Forecast
Index is highlighting noteworthy wind gusts during this period,
especially in the typical downslope areas in the western Champlain
Valley such as Ticonderoga, and east of the Greens. Maximum wind
gusts on Saturday for much of the region look to be in the 30 to 40
MPH range, with a few gusts closer to 45 MPH favored in the
localized areas previously mentioned. As winds decrease, potential
for low temperatures Saturday night to fall below -20 increase into
the 10-20% range in much of north central Vermont and 20-60% in much
of northern New York away from the Champlain Valley. All model
clusters of 500 millibar heights show the upper level low on Sunday
parked to our east/northeast, supporting continued reinforcement of
Arctic air and high confidence of very cold weather continuing
through the weekend. Noting that as we move through February
temperatures tend to warm, Sunday`s maximum temperatures look
particularly extreme relative to climatology (along the lines of 25
degrees below normal). Subtle differences in the pattern exist,
which leads to varied snow shower/upslope snow chances Sunday into
Monday.

KEY MESSAGE 2: While some light and relatively localized snow showers
are possible on Thursday associated with a weak cold front and
associated instability/upslope northwesterly flow, much more
widespread snow shower activity is expected Friday afternoon, and
especially the nighttime hours, as a strong Arctic cold front moves
through the area. In addition to scattered snow showers during the
day associated with height falls and cyclonic flow out ahead of the
front, organized snow showers with possible embedded snow squalls
will form along the front. Limiting This idea is shown in
deterministic model guidance depicting a sharp wind shift/low level
convergence helping produce briefly heavy snow shower activity
before the air mass quickly becomes too dry and cold for additional
precipitation. Low level lapse rates and the resulting instability
(even 90th percentile SBCAPE is only reaches 5-15 J/kg) look
minimal, associated with relatively cool pre-frontal air at the
surface and poor (nighttime) timing of the front, so at this point
the risk of heavy snow showers looks limited until the more
dynamically driven precipitation arrives. An early estimate of total
snowfall for this event will be in the range of a few tenths to
locally a couple of inches, supported by  high snow ratios

KEY MESSAGE 3: Weak migratory high pressure will break down tonight
with clouds increasing overnight ahead of a weakening clipper-type
low. Skies will remain clear through the evening allowing for
temperatures to drop sharply after sunset. As a result, utilized
last night`s low temperatures and a blend of guidance to get a curve
for tonight. Lows should be in the single digits slightly below zero
for most locations with typically colder hollows ranging from 8 to
15 degrees below zero.

Decreasing supportive dynamics aloft will result in weakening of the
clipper type low supporting the surface circulation opening into a
trough as it moves into the region. This favors more isolated to
scattered coverage of showers except of directly down wind of Lake
Ontario into portions of St Lawrence County where showers will be
more numerous. Cyclonic curvature aloft settles over the region
through Thursday under a northwest surface flow pattern. Continued
intermittent snow showers are likely especially along the western
slopes of the northern Greens. Snow totals will be meager due to
very limited atmospheric moisture likely ranging from a dusting to
around 1 inch across the 48hr period. On the flip side, temperatures
be warmer with southwest flow Tuesday/Wednesday - feeling almost
balmy with highs in the low/mid 20s rather than single digits and
teens of recent.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Largely ideal conditions for flying are in
place with light winds and clear skies over the next six hours,
and beyond for most sites. The biggest uncertainty will be with
regards to timing and formation of any low stratus/fog, which
is expected overnight at MSS (greater than 70% chance), likely
at SLK (~60%), and unlikely elsewhere (~20% or less). Light
southwesterly flow increasing slightly with the approach of a
weak trough will tend to boost low level moisture just enough to
produce a shallow cloud deck. For MSS have indicated a
prevailing MVFR deck arriving at 05Z, which may not be
persistent initially but will tend to become overcast with time
as moisture thickens especially towards 12Z; light, dry snow is
possible at the end of the TAF period, as well. Meanwhile, SLK
has a greater chance of any ceilings that develop to be in the
IFR category, but forecaster confidence in occurrence is low
enough to only show FEW005 at this time. Otherwise, light and
terrain driven winds are expected through the TAF period, which
could lead to vicinity fog at BTV towards daybreak. Again,
chances are too low to indicate in the TAF.

Outlook...

Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHSN.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
Wednesday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Thursday: Mainly VFR, with areas MVFR possible. NO SIG WX.
Thursday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday: Mainly MVFR and IFR, with areas VFR possible. Likely SN.
Friday Night: Mainly VFR, with areas MVFR possible. Chance SN.
Saturday: VFR. Slight chance SHSN.

&&

.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.

&&

$$

WHAT HAS CHANGED...Boyd
DISCUSSION...Kutikoff/Boyd
AVIATION...Kutikoff
EQUIPMENT...NWS BTV