Swanton, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

933
FXUS61 KBTV 090220
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1020 PM EDT Tue Oct 8 2024

.SYNOPSIS...
Scattered showers will continue each afternoon within a very
unstable environment under an upper low. Some showers may
contain graupel or even a rumble of thunder, especially
Wednesday afternoon. Elevations above 2500 feet are likely to
see some snow mix in during the overnight hours Wednesday night.
Temperatures will remain near or below normal, with Thursday
expected to be the coolest day of the week. Unsettled conditions
will continue into the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 1015 PM EDT Tuesday...Scattered showers continue to drift
across northern NY at this hour, and will keep gradually pushing
eastward overnight along with the upper shortwave trough. Some
clearing was noted across central/southern VT out ahead of this
activity, with some patchy fog developing in the favored river
valleys. Temperatures dipped down into the upper 30s/low 40s
where clearing occurred, as well. Do expect that additional
clearing will take place from west to east once the shortwave
and associated showers exit into NH, which should allow
temperatures to drop into the mid 30s across the
northern/central Greens. Therefore, the Frost Advisory still
looks good. The forecast has this all pretty much covered. Only
changes needed with this update were some tweaks to PoPs and
temperatures to match the latest trends.

Previous discussion...An upper-level low centered over central
Quebec will drop southward over the next 24 hours. Several
shortwaves will wrap around the low and impact our forecast
area. The first shortwave is currently digging into western Lake
Ontario, resulting in a blossoming of showers upstream. Along
and ahead of this wave, spotty convective showers over our
forecast area will expand in coverage late this afternoon into
this evening. This wave is progged to move through our area late
this evening towards midnight. This timing will coincide with
the loss of the best diurnal instability, but still steep enough
lapse rates in the mid-levels to support convective showers.
Behind the shortwave, there may be a brief window for broken to
overcast skies to briefly scatter out towards dawn, which could
allow for the formation of some localized valley fog and allow
temperatures to quickly drop. Have continued with the Frost
Advisory for Washington, Lamoille, and Orange Counties in
Vermont from midnight tonight until 9 AM Wednesday. However, any
frost development in these areas is conditional, depending on
breaks developing in the cloud cover that will allow
temperatures to fall enough to support frost development. Some
frost is also possible in portions of the northern Adirondacks,
although the growing season has ended there so no Frost
Advisories are no longer issued for these zones.

For Wednesday, the core of the upper low will drop closer to our
forecast area as a more robust wave moves in.  Lapse rates will
further steepen all the way through 500 mb, which is indicative of a
very unstable atmosphere. Showers will consequently be more
widespread in coverage Wednesday. Given 500 mb temps around
-30 deg C, some graupel is likely within the convective showers.
In addition, have included mention of some thunder in our NY
counties given the deep instability. High temperatures tomorrow
will be in the 50s for most areas, except remain the 30s to 40s
above 2500 feet. Showers will wane in coverage going into the
evening as snow levels drop to between 2000 and 2500 ft
Wednesday night. Locations above these elevations may see some
wet snow mix in with some rain Wednesday night, although
precipitation amounts will be light enough to keep snow totals
below an inch. Areas below 2000 feet are not expected to see any
snow Wednesday night.

&&

.SHORT TERM /THURSDAY NIGHT/...
As of 328 PM EDT Tuesday...Cyclonic flow aloft prevails associated
with mid/upper lvl trof located just north of Maine, while elongated
s/w energy is progged to be acrs our central/eastern cwa thru 18z
Thurs. This energy and axis of favorable mid lvl moisture should
produce additional showers, with highest probability acrs the north-
central VT mtns. Progged 850mb temps are pretty cold on Thurs with
values between -3C and -4C, resulting in highs struggling to reach
freezing at the summits and mid/upper 40s deeper valleys. Have noted
the MAVSLK is 42F and MAVBTV is 48F. Hikers should be prepared for
winter like conditions, especially on Thurs morning acrs the
summits. Areal coverage of precip wl quickly decrease on Thurs night
with lingering clouds acrs the trrn. However, if clouds quicker than
anticipated, temps wl be 4 to 6 degrees cooler than forecast attm.
Lows mostly in the 20s summits to near 40F Champlain Valley.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 328 PM EDT Tuesday...Large scale synoptic pattern continues to
feature mid/upper lvl trof acrs the NE CONUS thru early next week
with some amplification likely by next Monday into Tues. This
overall setup wl feature a rather unsettled pattern, especially for
Sunday into early next week, as guidance is coming into better
agreement with track/timing of northern stream low pres and
associated energy.

In addition, both the GFS/ECMWF are still highlighting near the
International Border area for best dynamics/moisture and associated
shower chcs on late Friday into Sat. I have continued with likely
pops (60%) near the International Border to schc (15%) acrs
Rutland/Windsor counties btwn 00z-12z Friday night/Sat morning. QPF
wl range from a couple tenths northern mtns to just a few hundredths
most of central/southern cwa. A much stronger synoptic scale system
arrives late Sunday into Monday with additional likely pops. This
s/w energy is progged to deepen a closed mid/upper lvl trof acrs the
NE CONUS by early next week that is progged to become vertically
stack. The deep cyclonic flow with favorable mid lvl moisture and
upslope flow wl produce additional shower chcs for Monday and Tues
of next week, along with plenty of clouds. For now have chc pops,
but likely/cat pops wl eventually be needed for the northern Dacks
and central/northern Greens. For temps have highs in the mid
50s/lower 60s for Fri/Sat, but fall back into the mid 40s to mid 50s
by early next week, which could be a little on the warm side. Lows
wl be highly impacted by clouds/precip and winds, but generally in
the upper 20s to lower 40s.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thursday...There will be scattered showers this evening,
but they will gradually taper off from west to east as the night
goes on. Conditions should be dry from late tonight into the day
tomorrow, before scattered showers redevelop tomorrow afternoon. A
few of these will be heavy enough to lower visibilities to MVFR or
even IFR. The heaviest ones could contain lightning or graupel.
Ceilings should remain VFR at all terminals through this period.
Localized fog formation is possible late tonight, and it could
briefly reach SLK, MPV or MSS. Winds will generally be light and
westerly during this period and LLWS is not expected.

Outlook...

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

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Frost Advisory until 9 AM EDT Wednesday for VTZ006-008-010.
NY...None.

&&

$$
SYNOPSIS...Duell
NEAR TERM...Duell/Hastings
SHORT TERM...Taber
LONG TERM...Taber
AVIATION...Myskowski