593
FXUS61 KBUF 101133
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
633 AM EST Mon Nov 10 2025

.SYNOPSIS...
An early winter arctic airmass will flow across the lakes today into
Tuesday with chilly temperatures and a transition to lake effect
snow southeast of the lakes. The lake effect will intensify this
evening with accumulating snows lasting into Tuesday night.
Relatively warmer air then arrives by Wednesday with rain mixing
back in.

&&

.NEAR TERM /THROUGH TONIGHT/...
A broad area of surface low pressure along the eastern seaboard this
today will deepen and become more compact as it takes a sharp
northward turn across Maine and into eastern Quebec. Concurrently,
the core of a deep upper level trough will gradually shift eastward
directly over the eastern Great Lakes. This will maintain a
continuous cold north to northwesterly flow across the lakes with
850mb temps hovering around -11C. General wrap-around light snow
showers across the region will gradually transition to a lake
effect/upslope regime through the course of the day today and become
focused south to southeast of the lakes as the flow backs. For this
reason, various winter weather headlines have been issued for
counties in these areas.

While most will continue to see at least on and off light snow
today, some mid-level drying of the overhead airmass will limit the
potential for more significant accumulations in most areas through
the day. The main exception will be along the Chautauqua Ridge where
added orographic enhancement could allow for several additional
inches of snow to accumulate. Any snow today will have an easier
time sticking to area roadways today (especially bridges/overpasses)
since aside from the northern Finger Lakes region, temperatures will
struggle to reach the freezing mark. For this reason have hedged
earlier with the start time for the advisories SE of the lakes,
though the `main show` for the lake effect will likely be tonight
into Tuesday morning. This is when deeper synoptic moisture will
wrap back across the lakes with increasing fetch across Lake Ontario
and an upstream connection to Lake Huron. This should allow for a
relatively well-defined band to climb northward across the NY/PA
line and another to develop along the southern shoreline of Lake
Ontario and eastward towards southern Oswego County. Still some
uncertainty in the possibility of a Georgian Bay band possibly
bringing some localized higher totals to portions of the Niagara
Frontier.

Forecasted highest accumulations in the areas SE of the lakes
through Tuesday morning are marginal between high-end advisory and
warning amounts, though with the preceding accumulations expected
along the Chautauqua Ridge today, have opted to upgrade to an LES
Warning there, with advisories in the other LE areas. Temps will be
cold tonight with lows in the 20s, a few readings in the teens at
the higher elevations.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Tuesday through Tuesday night will then feature broadening and de-
amplifying upper troughing across our region as a rather sharp/
elongated upper low ejects northeastward into Quebec...while another
embedded shortwave trough dives southeastward from central Canada to
the Upper Great Lakes. At the surface...this will result in low-
level ridging building eastward across the Great Lakes Tuesday...
then sliding off into New England Tuesday night as another broad
surface trough drops across Ontario and the Upper Great Lakes.

These developments will lead to the low-level flow steadily backing
from west-northwesterly to westerly during the course of Tuesday...
and then to an increasingly sheared southwesterly orientation
Tuesday night...which in turn will allow for steady warm advection
to develop Tuesday and continue through Tuesday night...with
consensus 850 mb temps eventually rising from -10C to -12C initially
to between -3C and -5C over Lake Erie and -4C to -6C over Lake
Ontario. Meanwhile synoptic-scale moisture will temporarily thin out
during the course of Tuesday in tandem with the building low-level
ridge...before increasing again Tuesday night with the approach of
the next surface trough.

Off Lake Erie...the initial cold WNW flow and an upstream connection
to Lake Huron should result in a fairly organized area of lake snows
continuing across southern Chautauqua and Cattaraugus counties into
Tuesday morning...with the backing flow/loss of the upstream
connection and drying attendant to the building low level ridge then
causing the activity to weaken as it drifts northward across
Chautauqua/Cattaraugus counties and into Southern Erie county
through the balance of the day. With diurnal warming of the boundary
layer and ongoing warm advection aloft...some limited rain may also
mix in across the lower elevations around the periphery of the band.
This should result in additional accumulations of 2-4 inches in the
Warning/Advisory areas southeast of the lake...before further
backing of the flow and increasing shear quickly sends the weakened
lake snows further north across the Niagara Frontier and into
Niagara county during Tuesday evening. The quick movement and
weakened state of the band by this time should keep any
accumulations across the Niagara Frontier Tuesday evening confined
to an inch or two. Overnight the band will linger mostly across
Niagara county with increasing/deepening synoptic moisture leading
to some re-strengthening...however by this time the increasingly
warmer environment will also be coming into play...and should help
to cut down on additional accums/possibly even allow some rain to
mix in.

Meanwhile off Lake Ontario...the initial cold WNW flow should direct
decent lake snows across the Monroe county-southern Oswego county
corridor through the morning...before the aforementioned ridge and
associated backing flow/drying causes these to also weaken and drift
northward mostly into Oswego county by evening. Additional accums
in the Advisory area during Tuesday look to be on the order of 2-4
inches...with most of this coming during the morning as increasingly
marginal boundary layer temperatures and the weakening nature of the
activity should result only limited additional accums during the
afternoon. The lake snows should then drift further north across the
North Country and into northern Jefferson county/the Saint Lawrence
Valley Tuesday night while continuing to weaken as the flow backs
and becomes increasingly sheared. Expect another general 1-3" east
of Lake Ontario as these drift north Tuesday night...with the
greatest amounts found across the Tug Hill.

Wednesday and Wednesday evening the axis of the surface trough will
pivot across our region...with an initially sheared southwesterly
flow at the start of Wednesday veering to westerly and eventually
becoming better aligned again off both lakes. The timing of this
wind shift remains somewhat in question given continued differences
amongst the guidance suite...but should generally take place
sometime during the late morning/afternoon off Lake Erie...and late
Wednesday/Wednesday evening off Lake Ontario...with a general
westerly flow then expected through the remainder of this period.
This will result in lake effect activity northeast of the lakes
Wednesday morning shifting back southward to areas east of the lakes
as winds veer Wednesday afternoon and evening. Meanwhile...the
passing surface trough will also likely generate at least some spotty
light pcpn of its own outside of the main lake effect areas.

At the same time...850 mb temps will warm to between -2C and -4C
areawide...with diurnal warming of the boundary layer pushing temps
back up into the mid 30s to mid 40s during Wednesday. The resultant
warming thermal profiles should result in progressively more rain
mixing in during the day...with the lower elevations likely seeing
ptype change over to all rain for the afternoon. The exact timing
and speed of this transition will dictate how much additional snow
we`ll see during the day Wednesday...with the best chances of any
snow and associated (likely minor) accumulations coming during the
early morning hours northeast of the lakes...and across the higher
terrain east of both lakes. Additional mixed lake effect rain and
snow will then continue east of the lakes Wednesday night...with
additional minor to modest accumulations possible across the higher
terrain.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Thursday and Friday our region will remain under the influence of
upper-level troughing...with the axis of this gradually migrating
eastward to the Canadian Maritimes over time. This will maintain
below normal temperatures across our region (though nowhere near as
cold as Monday-Tuesday) through the end of the work week...along
with a general westerly to west-northwesterly flow that will
gradually dry out over time as low level ridging begins building in
from the west. Consequently...lingering areas of lake effect pcpn
east and southeast of the lakes Thursday will gradually diminish
from west to east over time through the end of the work week...with
marginal temperature profiles allowing ptype to transition to mostly
rain/some higher elevation wet snow each day...then back to more in
the way of snow at night. Outside of these...conditions should tend
to be mainly dry.

By Saturday...generally dry and quiet weather is expected with our
region directly under the influence of an elongated surface ridge...
before the next (and notably warmer) low pressure system brings
renewed chances for some rain to our region by later Saturday
night/Sunday...along with temps climbing back to a little above
average.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Mainly MVFR/IFR today with light snow showers continuing across the
region, particularly south of Lake Ontario. Cigs will gradually
improve to mainly MVFR though periods of MVFR/IFR vsbys will be
possible through this afternoon.

As flow becomes more northwesterly through the course of the day and
into tonight, snow will transition to a lake effect regime focused
southeast of the lakes with localized IFR. This said, confidence
remains relatively low in potential impacts at the TAF sites
tonight. The southern end of the Lake Ontario band may periodically
clip KROC but remain south of KART. Heavy impacts to vsbys will be
possible at KJHW mainly after 06z. Finally, a lake band stemming
from Georgian Bay could materialize and bring localized impacts to
KBUF/KIAG. Outside of the main lake effect areas, MVFR cigs and VFR
vsbys will prevail tonight.

Outlook...

Tuesday through Tuesday night...Lake effect snow and local IFR/LIFR
southeast of the lakes, VFR/MVFR with scattered light snow showers
elsewhere.

Wednesday...MVFR/IFR with rain and snow showers, especially east and
northeast of the lakes. Windy.

Thursday...Areas of MVFR with rain and snow showers likely,
especially southeast of the lakes.

Friday...MVFR/VFR with a chance for rain and snow showers.

&&

.MARINE...
Surface low pressure along the eastern seaboard today will deepen as
it takes a sharp northward turn across Maine and into eastern Quebec
tonight. Northwesterly breezes will remain elevated across the lakes
on the backside of this system through tonight. Winds will then turn
westerly later Tuesday and further strengthen. This will result in
long duration SCA conditions on all nearshore waters of both lakes
as outlined below. Confidence is increasing in winds hitting gale
force between Tuesday night through Wednesday night on the open
eastern Great Lakes waters.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 1 PM this afternoon to 1 PM EST
     Tuesday for NYZ003>006.
     Lake Effect Snow Warning until 1 PM EST Tuesday for NYZ019.
     Winter Weather Advisory until 1 PM EST Tuesday for NYZ020-085.
MARINE...Small Craft Advisory until 7 PM EST Tuesday for LEZ040-041.
         Small Craft Advisory until 7 PM EST Tuesday for
         LOZ042>045.
         Small Craft Advisory until 10 PM EST this evening for
         LOZ030.

&&

$$

SYNOPSIS...PP
NEAR TERM...PP
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...PP
MARINE...PP