Swanton, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

882
FXUS61 KBTV 161159
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
759 AM EDT Wed Apr 16 2025

.SYNOPSIS...
Upslope snow showers will continue through tonight, producing accumulating
snow in western portions of the Adirondacks and in the vicinity
of the Green Mountains. More seasonable and dry conditions will
return Thursday before another system brings more widespread
rain chances over the weekend. Mild and unsettled weather
continues early next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 758 AM EDT Wednesday...Forecast is generally in good shape.
Dew points have continued to trend a bit higher than model
guidance, and snow showers unexpectedly blossomed over the last
hour along the spine of the Greens with Froude numbers
consistent with unblocked flow such that steady snow is falling
just east of the mountains across central Vermont at this hour.

As flow becomes supercritical over the next hour or so, this
activity should weaken. Road temperatures in this corridor are
mostly in the mid to upper 30s so mainly wet roads can be
expected.

Previous Discussion...A primarily westerly upslope,
mainly high elevation snowfall event will continue through
tonight. Deepening, broad low pressure near the Quebec/New
Brunswick border in Canada will occlude this morning. Its upper
level circulation, gradually shifting eastward just north of our
area, will continue to bring areas of enhanced spin spiraling
into our region on its western flank. A push of colder and drier
air this morning from the west will set the stage for lower
snow levels later today as a push of deeper moisture and
blossoming of precipitation occurs. The latest observations and
model guidance suggests there may be a push of snow showers late
this morning followed by a short lull this afternoon as Froude
numbers become supercritical unblocked. Then a resurgence of
more widespread snow should develop this evening as a more
typical northwest (or at least west-northwest) upslope regime
sets up with the upper level low departing to the northeast.
This pattern supports some heavier precipitation rates for a few
hours possible farther south into the central Greens/Green
Mountain National Forest where 1 to 4 inches could accumulate
above 2500 feet. Farther north and across the Adirondacks the
previous forecast is largely unchanged with Jay Peak still
looking most primed to see a total near one foot. Despite being
in mid-April and surface temperatures near freezing, the cold
air aloft and steep lapse rates actually suggest a moderately
fluffy snow with snow ratios largely 12 to 15:1.

As moisture gets squeezed out with drying aloft, eventually the snow
growth layer will desaturate leading to precipitation ending
overnight. Have maintained slight chances of snow showers in
northeastern Vermont into the day tomorrow with lingering cyclonic
flow and shallow moisture, but no measurable snow is expected beyond
tonight. Interestingly once this system departs very dry air will
arrive under a deep layer ridge, which along with lingering
northwesterly flow will produce quite low humidity levels as skies
clear tomorrow. Superadiabatic lapse rates along with downsloping
will lead to temperatures recovering into the mid 40s to mid 50s as
wintry weather becomes just a memory.

&&

.SHORT TERM /THURSDAY NIGHT/...
As of 412 AM EDT Wednesday...Ridging crests Thursday night with the
region under high pressure with clear skies and light winds. This
will be a good night for radiational cooling with temperatures
likely dipping below model means. In general, lows will be in the
lower 30s with some spots in the mid/upper 20s. Furthermore,
locations that received snowfall and maintain some snow cover will
likely dip below the first quartile values with lows around 20
degrees; coldest hollows in the Adirondacks could see the upper
teens, but will be largely dependent of how much snow falls and
extent of snow cover. Cloud cover will begin to increase near
daybreak on Friday from southwest to northeast ahead of the next
system.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 412 AM EDT Wednesday...Model guidance favors the next system to
move into the region late Friday with widespread rainfall Friday
night through Saturday morning. It should be noted that the national
blend of models is earlier with precip onset early Friday afternoon
while deterministic guidance has slowed to Friday evening/Friday
night. Its feasible that subsequent forecasts may shift towards
global guidance if this trend continues. CAMs are even later and
hang onto the dry air into early Saturday, but held off using these
solutions until we move more solidly into the mesoscale time window.
As such, current consensus shows increasing instability overnight
with ample southerly flow providing warm air advection ahead of this
system. At least isolated thunderstorms are expected over Friday
night over northern New York, spreading eastward after midnight
through daybreak Saturday. A few rumbles of thunder will be
possible. The St Lawrence Valley has the best chances of
thunderstorms with this system with MUCAPE exceeding 400J/kg
promoting more scattered coverage. South/southwest flow will help
temperatures warm to around/above 60 degrees for most locations,
potentially reaching 70 degrees towards southern Vermont and
portions of the Champlain Valley.

Pattern evolution past Saturday progs generally focus on a stubborn
Bermuda Ridge over the mid-Atlantic States with a deep moisture feed
around its western periphery pointed towards the Northeast. This
cold lead to a period of wet conditions with a quasi-stationary
boundary draped near the North Country. After a surface boundary
pushes through Saturday with drier conditions likely Sunday,
ensembles are somewhat split on where this boundary will end up, so
kept mainly 30-50% chances of showers Monday through Tuesday night.
Deterministic GFS is quite optimistic that the Bermuda Ridge will
move by midweek, but this forecaster`s experience and other guidance
like the EC suggest a slower pattern evolution with potential for
continued showers. On a positive note, temperatures shouldn`t
sharply drop, so precipitation type should be mostly rain. Highs in
the 50s to lower 60s seem reasonable given the expected longwave
setup. Lows warm from the 20s/30s Sunday night to 30s/40s early next
week as well.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Through 12Z Thursday...Variety of flight conditions driven off of
both ceilings, mainly MVFR to VFR, and snow showers, which are
lowering visibilities to 2 miles at times. Based on the increasing
Froude numbers think the MPV snow currently falling should wane this
morning with mainly flurries towards 14Z. Meanwhile still looks
favorable for upslope snow mostly at SLK during the period,
especially through 00Z. Have indicated chances of snow showers
mainly with PROB30 groups elsewhere. Generally looking west-
northwest winds sustained 8-12kts with gusts 15-25kts today,
relaxing just a little overnight. MVFR ceilings may linger into the
overnight at most sites.

Outlook...

Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. Chance SHRA.
Friday Night: Mainly VFR, with local MVFR possible. Definite
SHRA, Slight chance TSRA.
Saturday: Mainly MVFR, with areas VFR possible. Chance SHRA,
Slight chance TSRA.
Saturday Night: Mainly MVFR, with local IFR possible. Slight
chance SHRA.
Sunday: Mainly MVFR, with areas VFR possible. NO SIG WX.

&&

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

&&

$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff
SHORT TERM...Boyd
LONG TERM...Boyd
AVIATION...Kutikoff