769
FXUS61 KBUF 091132
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
632 AM EST Sun Nov 9 2025

.SYNOPSIS...
Low pressure will pass south and east of the region today, bringing
a mix of precipitation types to the region. Plain rain is expected
for most areas south of Lake Ontario through the day, with a wintry
mix across the North Country, and wet snow later today across parts
of the Niagara Frontier. Much colder air will move in behind the
system tonight with a changeover to all snow. Accumulating lake
effect snow is then possible through Tuesday. Unsettled weather
continues through midweek though temperatures will begin to warm
enough for rain chances to re-enter the forecast.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface low pressure will slowly translate from the Ohio Valley to
southern New England through this evening while weakly interacting
with a secondary area of low pressure off the Mid-Atlantic coast.
Combined with mid/upper level divergence from an ULJ poleward exit
region and broad scale height falls, expect several rounds of
precipitation to continue spreading northward into the region.

Thermal profiles continue to suggest that precipitation will be plain
rain for most of the area, with a couple of key exceptions. First,
across the North Country a cold northeasterly flow will remain
locked in place along the St. Lawrence Valley and into northern
Jefferson/Lewis counties. This should undercut the encroaching warm
nose to allow for snow and a wintry mix at times with freezing rain
and to a lesser degree sleet. This may occur through the remainder
of the morning, though better chances will come as colder air wraps
back around the departing low tonight before precip changes entirely
back to snow. Thus, a Winter Weather Advisory remains in effect for
this area until 7 AM Monday.

The other main exception will be across the Niagara Frontier early
this afternoon. A tight low/mid level thermal gradient on the
northwestern periphery of the passing low will be right over or in
close proximity to this part of the CWA. This uncertainty in where
exactly this gradient will be positioned makes for a challenging
ptype forecast, though guidance has been generally trending further
south and east with the low`s track, resulting in a colder overall
solution for WNY. There has also been a consistent signal indicating
a band of enhanced QPF downwind of the system`s cold conveyer belt.
Resulting wet-bulb cooling could facilitate a faster changeover to
snow with deep saturation extending into the elevated DGZ noted on
model soundings. To cover the potential for degraded visibilities
and several inches of wet snow this afternoon, have gone ahead and
issued an additional Winter Weather Advisory for Niagara and
Orleans where confidence is highest. With this said, areal soil
temperature obs are still in the mid to upper 40s and this rain/snow
transition is expected to happen while the sun is still up, so would
expect the majority of accumulations to be found on the cooler
grassy/elevated surfaces, with much less sticking to area roadways.

Regardless of how exactly today plays out, a much deeper plume of
cold Canadian air will wrap into the region behind the departing
system with 850mb temps tumbling to around -11C by early Monday
morning. This will allow for any wrap-around lake enhanced showers
to change over to snow and transition to more of a lake
effect/upslope setup. Prevailing low/mid level flow will be north-
northwesterly, directing multiple weaker bands of snow south of the
lakes. With sfc temps falling into the 20s overnight, much of the
area will likely see at least some accumulations overnight, though
the focus for more impactful snowfall amounts will be along the
Chautauqua Ridge and southwest of Lake Ontario. Given the
expectation for modest LES to continue well into Monday, have also
included Chautauqua County in the lastest round of Advisories,
though with a later start time.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
On Monday the core of a sharp upper-level low will make its way east
across the central and eastern Great Lakes...while its attendant
surface low deepens and lifts northward along the New England
coastline. Consequently...our region will lie within a deep
northerly flow of cold air (850 mb temps dropping to between -10C
and -12C) that will gradually veer more northwesterly through the
course of the day. This will allow for scattered to numerous lake
effect snow showers south of the lakes to gradually migrate to areas
southeast of the lakes over time...with the short fetch across the
lakes and limited synoptic moisture helping to mostly keep these on
the lighter side (on the order of an inch or less). This being
said...somewhat greater amounts will be likely along the Chautauqua
Ridge in Chautauqua county...where a boost from favorable
orographics may allow for a narrow swath of 1-3" accumulations
there. Coupled with the expected upslope and lake-enhanced snows
Sunday night (more in the Near Term section above on those)...these
will warrant the continuation of Sunday night`s Winter Weather
Advisory through 18z Monday...before a further decrease in moisture
causes the snow to weaken through the balance of the day. Otherwise
the day will be the coldest we`ve seen so far this season...with
highs only ranging from the upper 20s across the higher terrain to
the lower to mid 30s elsewhere.

Monday night through Tuesday night will then feature broadening and
de-amplifying upper troughing across our region as the initial 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 Monday night and
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
to west-northwesterly during the course of Monday night...westerly
during Tuesday...and then to an increasingly sheared southwesterly
orientation Tuesday night...which in turn will allow for steady warm
advection to commence Tuesday morning and continue through Tuesday
night...with consensus 850 mb temps rising to between -3C and -5C
over Lake Erie and -4C to -6C over Lake Ontario by the end of the
period. In turn...this will result in areas of lake effect pcpn
initially migrating to areas ESE of the lakes Monday night...then to
areas east of the lakes Tuesday and northeast of the lakes Tuesday
night...while also weakening Tuesday and Tuesday night due to the
aforementioned increase in shear and steady warming of the column...
which should allow for some rain to mix in during the day Tuesday.

With all the above in mind...the most favorable window for
accumulating lake effect snows looks to be Monday night into the
first part of Tuesday across areas southeast and east of the
lakes...however even during this time inversion heights only look to
peak around 7-8 kft...with available moisture beneath this decent
but not ideal. Coupling this with the fact that the lake bands will
also generally be on the move which may limit residence time in any
given location...forecast confidence is just not there to issue any
watches at this point. Best potential for the latter may again lie
across Chautauqua county where an upstream connection to Lake Huron
could briefly come into play for a time later Monday night into
Tuesday morning...however the heaviest snows from this could also
very well wind up mostly to our west over Pennsylvania and Ohio.
Will therefore just continue to highlight the possibility of
potentially headline-worthy snows in the HWO for now.

It`s also probably worth mentioning that while the northward shift
in the lake effect may eventually bring this across the Niagara
Frontier and Watertown areas Tuesday night...by this point the bands
should be in a weakened state and fairly mobile. So while there
could be some accumulations in these areas Tuesday night...these
currently look to be on the minor side.

As for temps...we can expect the coldest night of the season so far
Monday night when lows will range from the upper teens across the
interior of the Southern Tier and North Country to the lower-mid 20s
elsewhere...with the expected moderation in our airmass then
resulting in highs ranging through the 30s Tuesday...and lows in the
mid 20s to lower 30s Tuesday night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Wednesday through 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 through the end of the
work week...though temps will not be as cold was what was seen
earlier on in the week...with highs generally running in the upper
30s to lower-mid 40s each day. This will result in any precipitation
(both lake effect...and that from a passing surface trough Wednesday-
Wednesday night) to transition from more in the way of snow at night
to predominantly rain/higher elevation wet snow each day. The
greatest pcpn coverage appears to come Wednesday into Wednesday
night with the passage of the aforementioned surface trough...with
precip then gradually thinning out later in the week with increasing
low level ridging and drying of our airmass. The windiest conditions
will also likely be later Tuesday night and Wednesday with the
approach and passage of the trough...with gradually relaxing winds
expected Thursday and Friday. By Saturday...generally drier and
quiet weather is expected with our region directly under the
influence of an elongated surface ridge.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
An area of low pressure will move east-northast from the Ohio Valley
to near southern New England today. This will cause several rounds
of precip and deteriorating flight conditions to spread north into
the region through the day, with cigs predominately IFR or lower.

Precip type remains a forecast challenge through this afternoon.
Plain rain with VFR vsbys is is expected in most areas, though may
start out and/or end as snow or a wintry mix with FZRA across the
North Country (including KART). Further south, a tight temperature
gradient and moderate intensity precip could cause rain to change to
snow across the Niagara Frontier. Confidence is highest in this
occuring first at KIAG, potentially as early as 15z/16z, before
spreading eastward. Vsbys could very easily drop to IFR or lower in
this area of snow. PROB30s continue to be used in the TAF to cover
uncertainty in the exact changeover time.

Any rain or mixed precip types will change back to snow tonight
behind the passing system. Lake enhanced and upslope snow will
continue south of the lakes through the night with impacts to vsbys
at all terminals possible through at least 06z. A gradual
improvement is expected thereafter with more areas of MVFR emerging
late.

Outlook...

Monday...VFR/MVFR with scattered light snow showers southeast of the
lakes.

Tuesday...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 of
the lakes.

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

&&

.MARINE...
Low pressure south of the lakes will move from the Ohio Valley to
the Northeast Coast through this evening. A stiffening northeasterly
breeze will turn north-northwesterly behind the system tonight and
remain elevated through Monday night. Winds will then turn westerly
Tuesday and further strengthen. This will result in long duration SCA
conditions on all nearshore waters of both lakes as outlined below.

Winds will turn southwesterly beyond Tuesday with a period of Gales
possible Tuesday evening into Wednesday night.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 10 AM this morning to 7 AM EST
     Monday for NYZ001-002.
     Winter Weather Advisory until 7 AM EST Monday for NYZ007-008.
     Winter Weather Advisory from 7 PM this evening to 1 PM EST
     Monday for NYZ019.
MARINE...Small Craft Advisory from 10 AM this morning to 7 PM EST
         Tuesday for LEZ040-041.
         Small Craft Advisory from 10 AM this morning to 7 PM
         EST Tuesday for LOZ044-045.
         Small Craft Advisory until 7 PM EST Tuesday for LOZ042-043.

&&

$$

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