FXUS61 KBTV 220533
Area Forecast Discussion
National Weather Service Burlington VT
133 AM EDT Fri Sep 22 2023
High pressure remains firmly over the North Country bringing ample
sunshine with areas of fog in river valleys and colder hollows
overnight; some frost cannot be ruled out for in the Adirondacks.
Low pressure off the mid Atlantic tracks towards the Northeast for
the weekend bringing periods of rain with more isolated showers
potentially lingering through Monday into early next week.
.NEAR TERM /THROUGH SATURDAY/...
As of 106 AM EDT Friday...Fog is developing a bit quicker than
previously forecast across the typical river valleys tonight.
Other than that, all is quiet with this forecast update as
temperatures fall into the 30s and 40s under high pressure,
clear skies, and relatively light winds. Previous discussion
* Potential for localized frost/freezing fog in the Adirondacks
late tonight into early Friday morning.
High pressure will remain firmly in control of expected conditions
for the North Country through Friday. With the ridge axis overhead,
subsidence will be strong supporting night-time fog formation with
clear skies and light winds. Being another day removed from
precipitation, fog chances will be highest in river valleys and
colder hollows. With near surface soil moisture evaporating or
percolating, dew points below 2 meters should be able to fall
sufficiently cool to warrant some frost potential in the
Adirondacks, mainly in the vicinity of Saranac Lake. With
temperatures falling to around freezing, its feasible to have a
brief period of freezing fog as well in the typically colder
hollows. Elsewhere, temperatures will remain well above freezing
with no appreciable chances of frost. Otherwise, ridging crests
Friday with another day of ample sunshine. Continued drying will
promote conditions favorable for temperatures to warm above seasonal
averages in the upper 60s to mid 70s. As ridging breaks down Friday
night, cloud cover will begin to increase south to north limiting
radiational cooling and fog potential allowing temperatures to
linger in the 40s to low 50s for most locations.
.SHORT TERM /SATURDAY NIGHT/...
As of 318 PM EDT Thursday...All eyes have turned to potential
tropical cyclone 16 which is currently located over the western
Atlantic north of the Bahamas. There has been increasing model
confidence that this system, which is currently extratropical (cold
core) will develop tropical characteristics in another 24 to 36
hours. Whether it develops tropical characteristics or not, the
potential impacts, or lack thereof, will be the same. This system is
expected to hug the coastline as it approaches the Mid-Atlantic
coastline on Saturday with increasing chances for rainfall across
southern Vermont late in the day on Saturday into Saturday night.
There is still a lot of disparity amongst the deterministic guidance
how far north the precipitation shield will spread given
interactions between the potential cyclone and a frontal boundary.
Instead of going a deterministic approach with this forecast cycle,
we have leaned heavily on probabilistic and ensemble models which
shows a quarter of an inch or less across far southern Vermont with
a sharp gradient to no rainfall expected from central Vermont
northward and for much of northern New York. Still, with this
potential tropical cyclone in the early stages of development, a lot
of uncertainty exists until the RAOB network is able to sample how
the environment is reacting to this system. Stay tuned for more
updates but impacts at this time appear minimal at most.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 318 PM EDT Thursday...A sharp northern stream shortwave is
expected to help drive a cold front through the region on Sunday
which is expected to push out any lingering precipitation associated
with the potential tropical cyclone. Some models show the remnants
of the upper low attached the potential tropical cyclone phasing
with the longwave pattern on Sunday which could enhance
precipitation along the frontal boundary should this occur. However,
as mentioned before, confidence in any one solution remains low
until we have more time to sample this system. Following the frontal
boundary, Canadian high pressure is expected to settle into the
North Country which is expected to bring seasonable temperatures,
plenty of sunshine, and minimal chances of rainfall through much of
.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
Through 06Z Saturday...Fog is developing quickly across the
forecast area, namely in the typical river valley locations. Our
classic foggiest TAF sites, MPV and SLK, have gone down to LIFR
and are expected to stay there until around 13 or 14Z Friday.
They are bouncing around slightly, but should for the most part
have IFR cigs and/or vis for the rest of the night. EFK and MSS
seem to be bouncing more drastically between categories, and
thinking that a tempo group will be best to portray the way this
continues for the remainder of the night. RUT went down last
night, but tonight the drainage winds look to remain elevated
about 5-10 knots out of the southeast, which will likely keep
RUT VFR tonight, especially as it gets another day removed from
any rainfall. BTV and PBG should remain VFR as well again
tonight, but it is not out of the question that BTV could have
some briefly lower vis due to fog in the Winooski Valley
trickling toward the airport with light easterly winds.
Tomorrow, some light winds out of the southeast are expected at
all sites with few fair weather cumulus clouds dotting the sky
as high clouds overspread from south to north from a system in
the Mid Atlantic region.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Slight chance SHRA.
Sunday: VFR. Slight chance SHRA.
Sunday Night: VFR. Slight chance SHRA.
Monday: VFR. Slight chance SHRA.
Monday Night: VFR. Slight chance SHRA.
Tuesday: VFR. NO SIG WX.