Swanton, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

768
FXUS61 KBTV 271712
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
112 PM EDT Sun Jul 27 2025

.SYNOPSIS...
A compact weather system with embedded thunderstorms will track
along the Adirondacks and southern Vermont through noon, followed by
isolated to scattered showers and thunderstorms today. Hazy
conditions continue, but will diminish this afternoon. A bump up in
temperatures near 90 are expected for the early work week, with
chances for showers and storms mainly along the international
border. Hot weather will give way to cool, dry conditions by
Thursday after a Wednesday evening cold front. The dry spell will
continue into the weekend, but temperatures will begin to climb.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 146 AM EDT Sunday...A small, but sharp upper trough has been in
the process of developing. Scattered, elevated convection is
developing along and ahead of the feature. This feature makes its
closest approach between 4 AM and 11 AM. Despite weak flow aloft, it
will be sufficient to produce height falls with increasing elevated
instability overnight into early tomorrow morning. Elevated
convection is likely to intensify, and there`s a sharp axis of
deformation that forms along the base as the upper trough
intensifies. The heaviest precipitation will occur near this
feature. Almost all guidance keeps this feature to our south. WPC`s
slight risk (level 2 of 4) excessive rainfall outlook is just south
of our northern New York zones, at this time. It`s not entirely
impossible that this feature clips parts of the Adirondacks and
Rutland County. So it will be monitored closely.

Otherwise, this feature slides east by noon. Once that has cleared,
increasing sunshine will result in modest destabilization. There is
some shear present early, up to 40 knots even. However, by the time
we reach 500-1000 J/kg mid-afternoon, shear will quickly drop to
about 20 knots. So garden variety activity is expected. The wind
shift behind the trough occurs after sunset. It could spark
additional shower activity through about 2 AM. However, it will
still remain on the warm side in the 60-70 F range.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
As of 146 AM EDT Sunday...Channeled, zonal flow aloft without a
strong Bermuda High connection will result in a stream of warm to
hot continental air. The latest guidance from the NBM has swapped
Tuesday to be the warmer of our two hotter days ahead of a stronger
cold front. However, each day should top out mid-80s to lower 90s.
Confidence on which day is the hotter is a little lower than normal
due to timing differences in the frontal boundary. One set of
scenarios ensembles depict is an early arrival of the front very
late Monday into the overnight hours such that it has cleared the
area by midday Tuesday. The other scenario ensembles depict would be
a later arrival on Tuesday afternoon, which could make it a bit
warmer than Monday and have better opportunity for thunderstorms.
Summertime convection and its outcomes tend to have lower
predictability. So stuck very close the NBM/ensemble data showing
broad chances each day, but it`s possible either Monday or Tuesday
ends up completely dry. Overall, PoPs are highest along the
international border. If you`re looking for potential dry conditions
on both days, then southern and central Vermont are your best bets.

Highlighting Monday afternoon real quick, forecast soundings suggest
very dry mid-level air will mix to the ground Monday afternoon.
Broad subsidence and west-northwest flow makes this appear quite
reasonable. Even the usually biased high NAM 3km dewpoints are in
the 50s for a large portion of our forecast area Monday afternoon.
So dewpoints have been reduced from the NBM, which has resulted in
lower heat indices across the board. The potential for hazardous
heat on Monday looks relatively low at this time.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
As of 259 AM EDT Sunday...
** One more humid day on Wednesday with showers and
 thunderstorms possible, then a spell of somewhat cooler and
 dry weather is expected.

Wednesday still looks like a potentially active weather day.
There are signals for showers and a chance for some strong
thunderstorms ahead of a stronger thermal boundary at some point
in the day. Generally looking at higher model confidence on
higher shear being in place than higher CAPE, so instability may
be a limiting factor. Depending on the large scale forcing,
there could be a ribbon of deeper moisture and more widespread
showers then just isolated to scattered thunderstorms. Heat
backs off a bit on Wednesday as progged 925 millibar
temperatures drop a few degrees (mean ensemble values fall from
22-24 C to 19-21 C compared to Tuesday), supporting highs in the
low to mid 80s in most locations.

While some guidance continues to show lingering rain behind yet
another boundary on Thursday, our region will largely be high
and dry Thursday through Sunday as an expansive ridge of high
pressure slowly migrates eastward. Only Friday looks to be
anomalously cool, per NAEFS mean and EFI climatological tools, with
temperatures probably resembling what we saw this past Monday.
Generally the much cooler air mass that was on the table is
looking more likely to bypass us to the northeast, but for those
who desire warm, but not hot, days with low humidity should
have a nice weekend in store. As noted by the previous
forecaster, we`ll still need to monitor potential for wildfire
smoke to be advected in from the north, as it may be present
not far away later this week in northern Ontario.

&&

.AVIATION /17Z SUNDAY THROUGH FRIDAY/...
Through 18Z Monday...Radar shows area of steadier/heavier precip
is exiting our VT taf sites attm, while areas of IFR cigs are
lingering at EFK/MPV and RUT. Based on RAP sounding data and
trend in latest obs have tempo IFR cigs for another hour or two
at these sites with conditions improving to MVFR/VFR by 20/21z.
The taf challenge overnight is areal coverage of potential fog/br
and impacts from additional wildfire smoke. Upstream satl/obs
show another patch of clouds with sfc vis in the 4-8SM range in
HZ/FU, which is moving toward northern NY. Given the recent
rainfall, additional smoke, and mostly light boundary layer
flow, I have placed IFR or lower conditions at EFK/MPV/RUT and
SLK with MVFR at MSS/PBG and BTV from roughly 05z-12z tonight.
Still some uncertainty on cloud cover and wind fields, which
does limit my confidence level a little and will share my
thoughts with evening shift. Otherwise, south/southwest winds 4
to 8 knots become light north/northwest toward midnight.

Outlook...

Monday Night: VFR. Slight chance SHRA, Slight chance TSRA.
Tuesday: VFR. Chance SHRA, Slight chance TSRA.
Tuesday Night: VFR. Chance SHRA, Slight chance TSRA.
Wednesday: VFR. Chance SHRA, Chance TSRA.
Wednesday Night: VFR. Chance SHRA, Slight chance TSRA.
Thursday: VFR. Slight chance SHRA.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.

&&

.MARINE...
A lake wind advisory has been issued for this morning and early
afternoon across the broad portions of Lake Champlain. Latest
observations continue to show 22-26 knot sustained winds with
gusts between 30 and 33 knots. These winds will continue through
noon to 1 PM before beginning to weaken as gradient flow and the
winds within the mixed layer diminish. Waves in the broad lake
will build to 3 to 5 feet through noon before subsiding to 1 to
3 feet early this afternoon as winds begin to abate.

&&

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

&&

$$
SYNOPSIS...Haynes
NEAR TERM...Haynes
SHORT TERM...Haynes
LONG TERM...Kutikoff
AVIATION...Taber
MARINE...Clay