FXUS61 KBTV 210802
Area Forecast Discussion
National Weather Service Burlington VT
402 AM EDT Thu Sep 21 2023
High pressure will continue to build across the forecast area
through the end of the week, resulting in warm, sunny days and
clear, chilly nights featuring fog in river valleys and potentially
even some isolated frost in the Adirondacks. A low pressure system
will likely approach the area during the weekend, increasing cloud
cover, but uncertainty remains on whether we`ll receive any rain
showers from this system.
.NEAR TERM /THROUGH FRIDAY/...
As of 359 AM EDT Thursday...High pressure keeps the region fairly
quiet weather-wise through Friday. Today will feature seasonable
highs in the mid-60s in the Adirondacks and Northeast Kingdom and
lower 70s for the wider valleys with a slight warming trend tomorrow
- highs instead in the upper 60s to lower 70s, warmest in the wider
valleys. Otherwise sunshine will be abundant both days and winds
will be light. Tonight will be chilly with the lack of insulating
clouds and lows should drop into the lower/mid-30s in the cold spots
of the Adirondacks to mid-40s close to the mild waters of Lake
Champlain. It won`t be as chilly as last night, but there could
still be some isolated frost or freezing fog developing in the
Saranac Lake area of Franklin County, NY. Elsewhere, regular fog
will likely be plentiful once more under such clear skies and high
pressure, especially in river valleys.
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
As of 402 AM EDT Thursday...High clouds should begin to overspread
the North Country from south to north on Friday night as closed mid-
level low tracks northward from the Carolinas into the mid-atlantic
coast. Per NHC, system may acquire some subtropical characteristics
during this time frame, which should bring a strong poleward
moisture flux and surge of high precipitable water values northward
into southern New England by 12Z Saturday. Where the 00Z NWP
differences is whether this moisture plume can advect further north
into our area later in the day Saturday. The 00Z GFS suggests enough
of a blocking ridge to our north to limit the northward movement of
lower clouds and shower activity. Meanwhile, the 00Z ECMWF and
especially the 00Z Canadian are more aggressive in moving rain into
our region Saturday afternoon into Saturday evening. For now, have
kept the forecast closer to the 00Z GFS and GFS ensemble, which is
also closer to continuity from the previous forecast keeping bulk of
precipitation to our south during the forecast period. This means
just a slight chance of rain showers (20% PoPs) Saturday
afternoon/early evening across Rutland/Windsor counties, with dry
conditions further north.
Should see low temperatures Friday night mainly in the 40s, except
lower 50s in the Champlain Valley. On Saturday, the warmest
temperatures are likely in the northern Champlain and St. Lawrence
Valleys where some filtered sunshine is expected. Highs in these
valleys will generally reach the lower 70s. Meanwhile, thicker cloud
cover should keep highs in the 65-70F range across central and s-
central VT, as well as the nrn Adirondacks.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 402 AM EDT Thursday...Per short-term discussion, main question
will be northward translation of closed, deep-layer low pressure
system and associated moisture along the mid-Atlantic coastline, and
its interaction with a blocking high across Ontario and swrn Quebec.
NWP suite continues to show a variety of solns, with interaction
with a northern stream upper level low also a complicating factor.
Blend of deterministic and ensemble mean solutions appears to be
best forecast attm, which brings light precipitation into
Rutland/Windsor and possibly Orange county in s-central VT, but not
much further north as moisture is shunted to the east. Indicated max
PoPs of 30-40% attm across s- central VT Saturday night, before
decreasing PoPs during the day Sunday with current expectation that
bulk of precipitation shifts to our south and east. We`ll continue
to monitor these trends. Rainfall amounts attm <0.1" across
Drier/quieter weather returns for Monday/Tuesday with a surface
ridge over Quebec and a dry northerly flow. High temperatures in the
mid-upper 60s are generally expected for Monday/Tuesday.
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...Fog is beginning to blossom across the
river valleys of our forecast area tonight, dropping several
sites to IFR. Sites most likely to retain the IFR conditions
through around 12-14Z Thursday are KMPV and KSLK, as is typical
for them. KRUT was a little more unexpected, and it has since
gone back to VFR, but the return of IFR cigs can`t be ruled out
there and we have gone with a tempo for a few hours to
communicate the variability in category expected tonight. Two
other sites that could dip into IFR category are KEFK and KMSS,
though there is slightly less confidence with these. Guidance is
not in strong agreement about KEFK, and this site is known for
bouncing up and down through categories, so thought the tempo
group would best suit what we anticipate tonight. KMSS is also
not a slam dunk with guidance disagreeing, and there could be a
light wind there overnight due to valley channeling, but overall
the thick surface moisture forecast there should be enough to
bring it down to IFR periodically under such clear skies.
Lastly, KPBG and KBTV should be spared MVFR or IFR conditions
tonight, but if fog travels up the Winooski River Valley towards
the airport and we take on some light easterly winds again, it
could be vicinity fog or even high MVFR at KBTV. We are another
day removed from rain, but the pattern with high pressure makes
tonight ripe for fog and therefore lowered vis threatening IFR
conditions. By around 14Z Thursday, fog should be over and we`ll
have VFR conditions through the rest of the day.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Slight chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Slight chance SHRA.
Sunday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Monday: Mainly VFR, with local MVFR possible. NO SIG WX.
The KCXX radar will be down for radome repairs, with a return to
service around September 21st.
NY...Frost Advisory until 8 AM EDT this morning for NYZ029-030.