863
FXUS61 KBTV 120544
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
144 AM EDT Mon Oct 12 2026
.WHAT HAS CHANGED...
As of 332 PM EDT Sunday...
Winds have increased for Tuesday, along with chances for
thunderstorms.
&&
.KEY MESSAGES...
As of 332 PM EDT Sunday...
1. Some light rain associated with the remnants of Isaias will
spread across the region tonight, most persistent in southern
Vermont.
2. An active period of weather is expected Monday night through
Wednesday, including changeable temperatures, periods of rain, and
some rumbles of thunder associated a frontal system crossing the
area.
3. Lingering mountain rain showers Wednesday will give way to
drier and briefly mostly clear conditions for Thursday.
4. A strong low pressure system sweeping through the St.
Lawrence Valley will likely bring widespread rainfall and breezy
conditions Friday into Friday night, followed by a sharp cooldown.
&&
.DISCUSSION...
As of 332 PM EDT Sunday...
KEY MESSAGE 1: The former tropical cyclone Isaias is spinning
over eastern Kentucky this afternoon, moving towards the east-
northeast at about 22 MPH. Counterintuitively, there is very
little rain around its circulation; instead, the bulk of the
rain associated with its remnants is well to its northeast
across the Mid-Atlantic region and southern New England, where
a plethora of moisture transport from the Caribbean and Gulf is
being drawn northward out ahead of the system, as evident in
advective layer precipitable water satellite products today.
This advection should support further northward push of rain,
eventually overspreading our region late this afternoon,
gradually filling in towards northern Vermont and northeastern
New York tonight before retreating to the east as favorable lift
and moisture quickly departs as low pressure likewise exits.
The details on the start time of rain and how far north
precipitation reaches before spreading more towards the east
remains difficult to pin down. High confidence of rain remains
across southern areas, and observational trends have actually
been a touch faster than the consensus with rain already
reaching southern counties in Vermont early this afternoon.
Therefore, think the reversal of the trend from last night looks
reasonable, in which some rain will probably reach all of the
way to the International Border, with generally increasing
amounts as you go southward. Potential of seeing high end
amounts from 24 hours ago in our southern areas in the 1 to 1.5"
range has decreased, with the latest 90th percentile values
mainly in the 0.5" to 1" range. The expected storm track is far
enough south that the better frontogenesis, even in the mid-
levels, will remain outside of our region to reduce chances of
heavier rainfall rates. Rain will gradually taper off and pull
away after midnight, with northern/western areas only seeing up
to a couple hours of rain.
KEY MESSAGE 2: As high pressure builds southward over eastern Canada
tomorrow night, shallow cold and dry air will seep in from
eastern New England and dam up against the Green Mountains and
spill down the St. Lawrence and Champlain valleys. Meanwhile,
strong warm air advection above that layer will surge in from
the southwest out ahead of a wave of low pressure moving
eastward across the Great Lakes. The resulting inversion will be
quite robust and serve to produce typically substantial
temperature variations in our region, and with frontally forced
rain showers, elevated convection will be capable of producing
thunder. The latest calibrated REFS thunder probabilities are an
impressive 70-80% in western portions of St. Lawrence County,
tapering off to around 50% near the Vermont/New York border, and
further dropping to about 20% by the New Hampshire border. As
we get into the HRRR window, these numbers may fall, but the
general idea is that signals for showers with embedded thunder
during the day on Tuesday continue. Along with the thunder is
the expected swath of moderate rainfall and near certain rain
chances through the day. A rare washout type of scenario is
likely, although a window of drying during the afternoon is
possible if the surface boundary was to wobble farther north.
Meanwhile, with near-surface winds out of the south/southeast and an
impressive east-west pressure gradient, winds may become marginally
strong, including in the eastern Champlain Valley where an
easterly component to the wind could help boost temperatures as
well. For now with some uncertainties in the magnitude, have
stayed shy of the highest wind potential in the deterministic
forecast, but expect a windy day in the mountains and lakes,
especially in northern Vermont. The mean REFS wind gusts show
potential for near Wind Advisory (46 MPH gusts) criteria
downwind of the western slopes of the Greens in particular,
along with near 35 knot winds on the broad waters of Lake
Champlain.
It remains a challenging temperature forecast. The AIGEFS has
trended towards the latest run of the GFS with regards to
maintaining northeasterly flow in the northern St. Lawrence
Valley. Temperatures here are incredibly difficult to forecast
with this type of system, as a northeast drainage wind would
hold temperatures in the 40s while a flip to the southwest would
allow temperatures to surge through the 60s. As consensus
improves, would expect future forecast high temperatures may
become much cooler, but we have continued to lower highs most
appreciably in eastern Vermont where hourly temperatures only
gradually warm through the upper 40s to low 50s.
KEY MESSAGE 3: The long term period begins on Wednesday with a
moderately strong WNW mid-level flow regime in place across the
North Country. The period will generally feature mostly cloudy
conditions with some lingering rain showers possible, especially
focused across the higher terrain. By Thursday, sfc high pressure is
forecast to build in from the Ottawa Valley. Increasing subsidence
associated with this feature will help dry out the trapped
cloud/moisture layer at 4-6kft, allowing for some partial clearing.
Valley high temperatures for both Wednesday and Thursday will
generally run in the 50s, which is near to perhaps a degree or two
below seasonal levels for mid-October. The quiet weather will be
short-lived, however, as the sfc anticyclone translates eastward
into the Gulf of Maine by Thursday night, setting up a return S-SE
flow and increasing clouds ahead of our next frontal system. We may
see Lake Wind Advisory criteria with developing southerly winds on
Lake Champlain for Thursday night into Friday morning.
KEY MESSAGE 4: The main highlight for the long term period arrives
Friday into Friday night as a vigorous H5 trough and strong low
pressure system sweep through the St. Lawrence Valley. This system
will likely bring widespread rainfall and breezy conditions to
Vermont and Northern New York. Widespread rainfall amounts between
0.5 and one inch appear likely based on latest NWP consensus, and
PoPs for late Friday are in the 70-90% range.
As the trailing cold front sweeps through, the potential exists for
much cooler conditions for next weekend. The 12Z GFS depicts a
particularly deep trough, consistent with previous runs. The 850mb
temperatures on the GFS drop to -7C to -8C by 18Z Saturday, and then
down to -8C to -9C by 18Z Sunday. While it is worth noting that the
GFS tends to have a cold bias in these setups, the current forecast
confidently reflects the potential for below-normal temperatures
based on the broader 12Z NWP model suite. Expect highs generally in
the mid-upr 40s for both Saturday and Sunday.
With a northwesterly flow and sufficient moisture in place, we
cannot rule out upslope/mountain snow showers or flurries next
weekend, with some minor summit-level accumulations possible. Once
the system exits and skies finally clear, this autumn snow against
the remaining fall foliage at low elevations could make for a highly
picturesque and contrasting view across the high peaks of the
Adirondacks and Vermont`s Green Mountains.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Through 06Z Tuesday...Light rain is ongoing at SLK, PBG, BTV,
MPV, EFK and RUT. A period of IFR cigs expected at KSLK between
through 14Z, otherwise mainly MVFR-VFR. In general, TRRN OBSCD
across nrn NY and VT during the pre-dawn hours and early morning
hours on Monday. Lgt/vrbl winds with a shift to the NNW aft 12z
Mon and remain less than 10 kts.
Outlook...
Tuesday: Mainly MVFR, with areas IFR possible. Definite SHRA,
Slight chance TSRA.
Tuesday Night: Mainly IFR, with local MVFR possible. Definite
SHRA, Slight chance TSRA.
Wednesday: Mainly MVFR, with areas IFR possible. Slight chance
SHRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Slight
chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. NO SIG WX.
Thursday Night: VFR. Slight chance SHRA.
Friday: Mainly MVFR, with areas IFR possible. Likely SHRA.
&&
.MARINE...
As of 332 PM EDT Sunday...Southerly winds in the 20-25 kt range
will continue through this evening before tapering off
overnight. These winds will likely produce waves in the 3-4 feet
in portions of the broad waters and Inland Sea, before likewise
tapering off to under 1 foot towards daybreak.
A period of stronger wind and wave action is expected for
Tuesday, with a south-southeast channeled wind event expected
along with gusty showers.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
WHAT HAS CHANGED...Kutikoff
DISCUSSION...Kutikoff/Banacos
AVIATION...Banacos/Neiles
MARINE...Myskowski
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