Colchester, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

059
FXUS61 KBTV 211940
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
240 PM EST Thu Nov 21 2024

.SYNOPSIS...
A long duration rain event with mountain snow showers is currently
underway with rain and snow likely to linger through the weekend.
This beneficial rainfall comes after a prolonged dry spell and is
welcomed as no impacts are expected from this system. A brief break
in precipitation is expected Friday afternoon but otherwise we will
remain showery and cool through the upcoming weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 240 PM EST Thursday...We continue to see a complex storm system
impacting the northeastern US this afternoon with widespread
rainfall and mountain snow showers impacting Vermont and northern
New York. Presently, an anomalously strong upper level low is
situated across the Ohio River Valley with a surface low displaced
to the southwest of the upper low center. In addition, we have begun
to observe a new double barrel low pressure system developing near
Benchmark. The strong upper low to the west has cut off the supply
of cold air and have funneled the coldest air across central and
southern New York where the bulk of snowfall has been seen thus far.
The coastal low is actually helping to keep the warmer air locked
into the region as we see the onset of increasing easterly flow off
the western Atlantic. The precipitation currently overspreading the
region is tied to a frontal occlusion attached the surface low well
to our west. Temperatures aloft are cooling slightly from a
combination of the wet-bulb effect and very subtle cold air
advection. Webcams have shown that Whiteface Mountain and Killington
have both switched over to snow with temperatures between 28 and 30
degrees. Other summit sites remain between 33 and 35 degrees but
those too will be dropping shortly as precipitation continues to
fall through dry air and cools off the surface.

As you head down below 4000 ft, we have seen just plain rain as
temperatures continue to hover in the upper 30s to mid 40s. Rainfall
thus far has ranged from just a few hundreths across northeastern
Vermont all the way to three tenths of an inch across the St.
Lawrence Valley. Basically, everything remains on track from the
previous forecast. Models have come into much better agreement
showing that warm air will remain entrenched in the lower
elevations, especially tonight and much of Friday to where we have
continued to fine tune our snow level grids. For tonight, we expect
snow levels to drop to about 2500 feet across northern New York but
will remain at or above 3800 ft across Vermont.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
As of 240 PM EST Thursday...Cold air will finally begin wrapping into
Vermont Friday afternoon and evening as the upper level low moves
into western Massachusetts/western Connecticut. However, the colder
air will likely coincide with a noticeable dry slot where the
majority of the late morning through early evening hours will have
very little, if any, precipitation falling across the region. Winds
during this time about 1000 ft will be easterly given the position
of the upper low which would favor some downslope conditions along
the western slopes and upslope across the eastern facing slopes. As
both the coastal low and surface low shift further offshore late
Friday night into Saturday morning, we will see wind shift back to a
more climatological northwest direction which will then begin the
upslope machine. Precipitation isn`t likely to be heavy Saturday or
Sunday but with continued upslope flow, we could easily see 1-2
inches of accumulation every 6 hours along the western slopes that
will add up over time.

Snow levels on Saturday will drop to 1800 to 2200 feet which will
allow for some mid-mountain snow accumulations but most of the
population centers for the North Country will continue to see rain
showers while the mountains get in on all the snow action. We will
see snow levels drop to 1200 feet Saturday night which may allow for
some very minor accumulations to occur along the foothills of the
Green Mountains but any accumulations will remain well under an inch.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 240 PM EST Thursday...Vertically stacked low pressure will be
moving away into the Canadian Maritimes on Sunday, leaving
northwesterly flow and orographically enhanced showers in its wake,
mainly in the morning hours before precipitation tapers off in the
afternoon. Snow levels will sit at about 1,000 to 2,000 feet
elevation. Everywhere below 1,000 feet is expected to see only rain
showers. Additional rainfall amounts of up to 0.20" are possible in
terrain areas, especially the Greens, while additional snowfall of
up to about 3 inches is possible above 2000 feet elevation.
Northwesterly wind gusts could reach up to 15-30 knots off the
departing low, perhaps up to 40 knots at the peaks and in
downsloping gusts on eastern slopes of the mountains. Highs Sunday
will be seasonable in the upper 30s to upper 40s, but may feel much
chillier (mid 20s to upper 30s) due to the wind. Gusty winds will
taper off a bit into the overnight hours on Sunday, but remain at
about 10-25 knots. Temperatures will fall into the 20s and lower 30s
overnight Sunday into early Monday, and precipitation will finally
come to a complete end by then.

There will be brief ridging and a break from precip on Monday before
another trough arrives Monday night/Tuesday with associated surface
low and occluding frontal boundary. Highs Monday and Tuesday will be
mild in the 40s during this period thanks to the brief ridging and
then influx of milder air with the system. This will raise snow
levels to above 3000 feet and produce mostly rain on Monday night
before cold air advection follows on Tuesday and snow levels could
plummet to 1000 feet again, allowing snow to mix in at these
elevations and higher before the system moves out Tuesday night.
There`s the potential at the onset of this system for some freezing
rain type precipitation to occur as model soundings produce a warm
nose, but it`s too soon to set any details on p-type in stone. Cold
air advection following the system could keep snow showers lingering
at high elevations into Wednesday. After this, models diverge on the
timing and placement of the next wave to come through the forecast
area late next week. Overnight lows are expected to take a plunge
into the teens to mid 20s by Thursday night.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Through 18Z Friday...Conditions are extremely variable for many
sites this afternoon, with BTV, RUT, and PBG representing the
most VFR observations, though RUT and PBG are currently
bouncing between VFR and MVFR, while MSS is holding most
reliable for IFR conditions. SLK is bouncing up and down
between all flight rules, while EFK is the most steady in MVFR
conditions. Unfortunately, this makes the future a bit chaotic
to forecast. BTV, PBG, EFK, and RUT are expected to remain
mostly MVFR ceilings and visibilities for the next 24 hours,
though heavier rain could produce IFR vis about 2 miles on and
off. SLK and MSS look most likely to have IFR ceilings over the
next 24 hours as lower clouds focus on northern New York.

MPV is expected to join BTV, PBG, EFK, and RUT in mostly MVFR
this evening with perhaps periods of heavier rain causing 2
miles vis. All that said, mostly 1500-2000 foot ceilings
anticipated in the Champlain Valley and eastward for the next 24
hours, but pockets of heavier rain could cause IFR conditions
at any site. Conditions will just begin to improve right at the
end of this TAF period, around 18Z Friday. Gusty winds will
begin out of the northeast around 04Z-09Z Friday, gusts 15-30
knots anticipated through the end of the 24 hour TAF period.
LLWS is expected to dominate sites outside of the wider valleys
as easterly winds pick up over parts of Vermont and increase at
2000 ft agl up to 40 to 45 knots. LLWS is a concern mainly for
SLK, RUT, MPV, and EFK. Most likely timing for LLWS will be from
09Z to 15Z Friday.

Outlook...

Friday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Saturday: Mainly MVFR, with areas IFR possible. Chance SHRA.
Saturday Night: Mainly MVFR, with local IFR possible. Likely
SHRA, Definite SHSN.
Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA, Chance
SHSN.
Sunday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Monday: Mainly VFR, with local MVFR possible. NO SIG WX.
Monday Night: Mainly VFR, with local MVFR and IFR possible.
Likely SHRA, Likely SHSN.
Tuesday: Mainly MVFR, with areas IFR possible. Likely SHRA.

&&

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

&&

$$
SYNOPSIS...Clay
NEAR TERM...Clay
SHORT TERM...Clay
LONG TERM...Storm
AVIATION...Storm