104
FXUS61 KBTV 221845
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
245 PM EDT Tue Sep 22 2026

.WHAT HAS CHANGED...
As of 245 PM EDT Tuesday...

Frost Advisories have been issued for the St. Lawrence Valley and
eastern Clinton County in New York, as well as for Franklin,
Lamoille, Chittenden, Washington, Orange, eastern Rutland, eastern
Addison, and western Windsor Counties in Vermont from 2 AM to 9 AM
Wednesday.

&&

.KEY MESSAGES...
As of 245 PM EDT Tuesday...

1. Seasonably cool and dry weather will continue through late
week, with patchy frost tonight, and likely Wednesday night.

2. Still a large spread in potential outcomes associated with coastal
system and if any rain/wind impacts our forecast area this weekend.

&&

.DISCUSSION...
As of 245 PM EDT Tuesday...

KEY MESSAGE 1: High pressure is settling in across the region with
clearing skies. The center of the high is actually to our north in
southern Quebec, but we will still enjoy the clear and calm weather
that is associated with it. Fair weather terrain cumulus will
dissipate this evening with a few high clouds remaining across
southern Vermont associated with a stationary boundary well south of
the region in the Mid-Atlantic. Patchy fog and frost are expected
tonight as clearing skies set up for good radiational cooling.
Temperatures will dip below 40 degrees for majority of the area,
outside of the wider valleys of southern Vermont. Widespread near
freezing temperatures will be possible across the Northeast Kingdom,
central Vermont, and the Adirondacks. Pocket mid to upper 20s will
be likely in isolated portions of the northern Adirondacks. Frost
Advisories have been issued for the St. Lawrence Valley and eastern
Clinton County in New York, as well as for Franklin, Lamoille,
Chittenden, Washington, Orange, eastern Rutland, eastern Addison,
and western Windsor Counties in Vermont from 2 AM to 9 AM Wednesday.
Frost will be less likely in areas near Lake Champlain, due to the
surrounding warmer water temperatures helping to moderate the
surrounding air. It should be noted that, as of 9/21, these products
will no longer be issued for the Adirondacks and Northeast Kingdom,
as median date of the first autumn freeze has passed. Thus, the
growing season is considered ended in these areas.

Through the mid to late week, temperatures will slowly creep up a
degree or two each day towards Thursday, with highs in the mid to
upper 60s, as the high drifts to the east. Portions of the eastern
Greens may see below normal temperatures continue Wednesday with a
cold air damming setup. Frost potential will continue Wednesday
night, though radiational cooling will be a touch weaker resulting
in less areal coverage of any potential Frost Advisories. Fog
chances will also see less coverage Wednesday night, though patchy
fog in the climatologically favored valleys of eastern Vermont and
the Adirondacks will still be possible. Clouds begin to build
Thursday into Friday as a nor`easter off the southern New England
Coast meanders. There is still a large degree of uncertainty with
regards to the evolution of the system, as it pertains to cloud
cover and precipitation chances. Currently it looks like Friday
should remain dry for now with PoPs below 30%. Regardless, a
tightening pressure gradient will develop across our area resulting
in some breezy to channeled winds potentially Friday afternoon.

KEY MESSAGE 2: The long term forecast challenge is evolution and
movement of deeply closed off sfc to 250mb cyclonic circulation and
potential impacts to our cwa. Latest guidance continues to indicate
a large spread in potential solutions between individual
deterministic models and associated ensemble members, especially
with regards to sfc low pres track and placement of precip. The 12z
trends in guidance shows embedded short wave being captured in the
cyclonic circulation, which helps to retro-grade sfc low pres
westward toward the Mid-Atlantic/SNE coast by Sunday. The 12z
ECMWF/ICON are most aggressive with advecting deep layer moisture
back into parts of our cwa, while GFS/CMC shows better potential
over central/eastern VT. The challenge will be a very sharp nw-se
moisture gradient btwn coastal system and strong/dry high pres
anchored over southern Canada. Could see band of moisture rotate
around cyclonic circulation toward VT on Sat/Sunday and fall apart
when they encounter deeper dry layer over our region. Latest WPC pop
grids have cutback on precip chcs by 15% to 30%, which seems a
little unreasonable given current trends. Feel these should be
increases based on latest data, with highest probability of
measurable precip acrs central/eastern and southern VT on Sat into
Sun.

Did note as the gradient increases between coastal low pres and
sfc high pres, progged 925mb to 850mb winds increase at 30 to 45
knots, which wl support a few gusts in the 20 to 35 mph range,
especially higher trrn and aligned north to south valleys. Temps
mostly in the 60s on Saturday/Sunday, and warm into the upper 60s to
lower 70s by early next week. Lows in the mid 30s to mid/upper 40s,
but could be warmer with more clouds/precip this upcoming weekend.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Through 18Z Wednesday...Aviation focus will be on timing and
coverage of fog tonight at our TAF sites. VFR conditions prevail
at all sites thru 06z with north/northeast winds 4 to 8 knots.
Winds become light tonight with clear skies, allowing for
favorable conditions for fog development. Highest probability
(60-70%) of fog/LIFR will be at SLK/MPV between 08-12z with
chance (30-40%) at EFK, and less than 20% at RUT/MSS/PBG and
BTV. Similar to last night, feel fog will be in the vicinity at
BTV and may impact the north end of the runway toward sunrise
off the Winooski River. Otherwise, any fog/low clouds should
lift by 13-14Z on Weds with VFR conditions prevailing.

Outlook...

Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Slight chance SHRA.
Saturday Night: VFR. Slight chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Frost Advisory from 2 AM to 9 AM EDT Wednesday for VTZ002-005-
     006-008-010-016>020.
NY...Frost Advisory from 2 AM to 9 AM EDT Wednesday for NYZ026>028-
     087.

&&

$$

WHAT HAS CHANGED...Danzig
DISCUSSION...Danzig/Taber
AVIATION...Taber