733
FXUS61 KBTV 212333
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
733 PM EDT Tue Oct 21 2025
.SYNOPSIS...
A cooling trend through the week will occur as high pressure
currently in place will give way to another large upper low
pressure area. Rain chances increase towards Wednesday morning
with some showers possibly produce lightning and graupel, then
improving conditions are expected later in the day. The low
pressure area will settle over the Great Lakes supporting
additional showers enhanced by the lakes Wednesday night
through Friday before a drying trend takes place.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 246 PM EDT Tuesday...Pleasant weather is here this
afternoon, with some light south winds at the surface and
westerly winds aloft out ahead of our next low pressure system
that is quickly following behind the last one. A band of clouds
is racing eastward into the area, with observations supporting
model guidance showing thickening clouds over time. While there
are some showers currently in western New York, this activity is
expected to diminish such that while brief, light rain is
possible, measurable rainfall is unlikely as the showers move
into northern New York early this evening and further shrivel
up.
Most model guidance continues to show rain blossoming to our
south tonight, probably in response to large scale forcing
including pressure falls downstream of the incoming trough east
of the Appalachians spine. South-southwesterly flow will draw
the steadier rain into eastern Vermont after midnight, although
rain will become likely farther west with time (at least a 66%
chance of measurable rain between 2-8 AM areawide).
The main weather of note for tomorrow remains the potential for
thunderstorms, again moving from south to north as another deepening
low pressure system is expected to move right over the area. The
latest HREF mean instability has increased a bit, with surface
based CAPE increasing quickly into the 500-750 J/kg range by
midday. Thunderstorm risk follows primarily from mid morning
hours through mid-afternoon, generally shifting northward with
time. We`re thinking the surface convergence is lackluster such
that precipitation will be disorganized, but the strong upper
level forcing and overlap of deep layer shear and instability
favors eastern portions of Vermont, especially in the Upper
Valley per EFI CAPE-Shear anomaly, for a couple of stronger
storms especially before noon. As typical for warm season
thunderstorms, convective allowing models have varying low-
level moisture profiles and associated mixing, and think
an average between HRRR and NAM3 will be a decent approximation.
There should be enough going for convection given low wet bulb
zero heights and high equilibrium levels, such that potential
hazards would be graupel and frequent lightning along with
gusty winds (up to 40 MPH). These atmospheric profiles rule out
potential for heavy rain such as what we saw on Monday, although
brief downpours will still occur in the storm cores.
Sharply lower precipitation chances then look reasonable as we
move through the late afternoon with mid-level relative
humidity dropping off in the wake of the surface low pressure
area, which should progress out of the area ahead of the upper
level low still incoming. Following a brief break in in
precipitation, tomorrow night showers should be ongoing downwind
of Lake Ontario to ideal cyclonic low-level flow parallel to the
lake`s long axis, and with more of a southerly component
downstream, showers will tend to expand across northern New York
west of the Adirondacks especially. As colder upper level air
moves eastward, the freezing level will lower to support a
changeover from rain to snow across the High Peaks towards
morning. Have continued to lower mountain temperatures per model
consensus of 850 millibar temperatures dropping to near freezing
by the end of the period. The combination of wet, cold, and
breezy conditions will produce potentially hazardous conditions
for those recreating in the mountains throughout the middle to
late part of the week, especially as the first wintry weather of
the season occurs.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 246 PM EDT Tuesday...Thursday will be a day of lake-
effect rain showers as colder air spills over the Great Lakes
and west-southwest winds (roughly 240 degrees) transport bands
into the Adirondacks and downwind at times into portions of
northern Vermont. Forecast soundings show typical cold season
type of showers with shallow cloud tops, so the thunder risk is
very low (peaking at 10% in southern St. Lawrence County). Snow
levels still look to be sufficiently low for our highest peaks
to see their first, wet snow accumulations of the season. 850
millibar temperatures only a little below freezing is not
unusual for this time of year, near the 30th percentile, but
combined with the precipitation it will be quite chilly on our
mountains. The stronger winds will tend to be as you go
southward and during the morning, when sustained winds between
925-850 millibars may be upwards of 25 MPH.
Some of the latest data shows yet another area of low pressure
trying to develop near the St. Lawrence Valley with a weak
surface front, helping to enhance rainfall chances Thursday
afternoon through Thursday night across western portions of our
region. Meanwhile, large scale lift ahead of the trough axis
leads to expansion of showers across Vermont, especially
northwestern areas into the northern Greens but also farther
east by Thursday night. All in all, quite an unsettled weather
pattern for this period with plenty of shower chances.
Temperatures will be quiet seasonable, ranging from the 40s to
mid 50s in the warmest spots in the valleys, slowly settling
cooler after dark and mainly above freezing.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 246 PM EDT Tuesday...Mid/upper lvl trof axis is directly
overhead at 12z Friday with potent s/w energy near the
International Border. This energy combined with pocket of
enhanced 850mb to 500mb rh>80% wl produce additional showers
acrs our cwa. The highest pops and heaviest qpf wl be acrs the
favorable upslope areas of the northern Dacks into
central/northern Greens. I have utilized adjust pop based on
climo tool to highlight highest pops in these areas, while drier
conditions are likely in the CT River Valley. 1000-500mb
thickness progs indicate values in the 530 to 537 dam range,
while 850mb temps are btwn -3C to +2C, supporting the idea of
slushy wet snow above roughly 3000 feet on Friday morning.
Modest caa prevails most of the day on Friday as progged 850mb
temps fall btwn -3C and -6C by 00z Sat, with 925mb temps near
0C, so a few flakes possible down to 2000 feet acrs the northern
mtns. Any accumulation of an inch or so would be confined to
above 2800 feet on Friday aftn. Also, utilized the mountain
adjust max T tool to highlight cooler temps in the mtns both
Friday and Sat, supported by the NAM/GFS guidance. This
indicates highs l/m 30s Friday and upper 20s/lower 30s Saturday,
while valleys are in the mid 40s to lower 50s both days. Any
lingering precip should slowly dissipate by Saturday as sfc high
pres builds into our region. Given the northwest flow from
925mb to 700mb on Saturday and lingering moisture, would not be
surprised if several rounds of light upslope precip persists
into the late morning/early aftn hours with plenty of clouds.
Eventually sfc high pres and ridging aloft develops with an
extended period of dry wx anticipated from Sunday through most
of next week. Initially a large diurnal swing is anticipated
from daily highs and nighttime lows, given dry airmass in place.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thursday...VFR conditions to prevail through the
first part of the TAF period, then showers overspread the area
from north to south 05z-10z, continuing through much of the rest
of the TAF period. These showers will contain mostly VFR flight
conditions with some intervals of MVFR visibilities possible in
the heavier precipitation. Eventually as winds slowly shift to
the southwest, expect MVFR cigs to develop at our mountain sites
after 06z Wed. Best potential for MVFR ceilings will be at
KSLK/KMPV/KEFK with a 20 to 25% of ceilings briefly dropping
below 1000 ft. Remainder of the terminals should stay primarily
VFR. Winds will be light overnight, becoming SW 5-10 kt after
sunrise Wed.
Outlook...
Wednesday Night: VFR. Chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. Definite SHRA.
Thursday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA.
Friday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Friday Night: Mainly VFR, with areas MVFR possible. Slight chance
SHRA, Slight chance SHSN.
Saturday: VFR/MVFR conditions possible. Slight chance SHRA.
Saturday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Sunday: Mainly VFR, with areas MVFR possible. NO SIG WX.
&&
.EQUIPMENT...
The TYX radar is down until further notice after a hardware
failure occurred. Replacement parts have been ordered and will
be installed. There is no ETA on its return to service.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Kutikoff
NEAR TERM...Kutikoff
SHORT TERM...Kutikoff
LONG TERM...Taber
AVIATION...Hastings/Taber
EQUIPMENT...BTV
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