NWS Area Forecast Discussion

FXUS61 KBUF 012355

Area Forecast Discussion
National Weather Service Buffalo NY
655 PM EST Wed Dec 1 2021

Deep low pressure will pass to the north of the area late tonight
and Thursday, with a trailing cold front crossing the area Thursday.
The main impact will be period of strong and gusty winds Thursday
over much of the area, with the strongest winds east of Lakes Erie
and Ontario. A few scattered rain showers are expected tonight,
possibly mixing with snow briefly across higher terrain. Rain
showers will continue Thursday, then change back to snow Thursday
night with some minor lake snows southeast of the lakes on Friday.


...Strong and gusty winds Thursday...

Radar imagery showing some weak returns across the area this
evening, but so far a dry sub-cloud layer is preventing this from
reaching the ground. Surface observations show some light rain
making it to the surface over NE Ohio and NW PA, and some of this
may move into the Southern Tier by mid evening.

Attention is on a deepening low moving east across Ontario and
western Quebec late tonight and across Quebec on Thursday. The warm
advection/isentropic upglide regime ahead of this system will bring
scattered showers tonight..Greatest moisture advection focuses
across the Southern Tier this evening, and eventually northeast into
central NY and east of Lake Ontario overnight, where the greatest
chance of measurable precip will be found. Mainly just a rain/snow
showers going to rain showers scenario with only light qpf if it
precipitates at all. One spot to watch though remains higher terrain
east of Lake Ontario as that area will have better shot at some
precip and soundings still show shallow/weak warm nose 3kft AGL
while temps at sfc are near freezing. This would be 4AM-7AM on Thu
before sfc temps warm above freezing. Kept as snow showers to rain
showers for now, but cannot rule out some other frozen precip such
as PL or -FZRA for a very brief period across high terrain.

Late tonight into Thursday winds become the main story. Decent
agreement 987-988mb low will be vcnty of Ontario and Quebec border
south of James Bay daybreak Thu. Still some variances in terms of
strength of low-level jet tied to the low ahead of cold front, but
45-50 kts is good average at this point. Soundings show generally
stable profile to start day in the pre-frontal environment. SW winds
increase quickly though, first along Lake Erie shore then spreading
across western Niagara Frontier including Metro Buffalo and Niagara
Falls by late morning. Wind gusts in the 35-45 mph range during this
time as well as across the higher terrain of western NY. There is
then brief window behind cold front passage with low-level jet 45+
kts still present and at least a weak pressure rise and onset of
cold advection to result in 45-50 mph gusts possible early to mid
aftn western NY, strongest Niagara Frontier and eventually shifting
along the shoreline of Lake Ontario from Rochester to the eastern
Lake Ontario region. Strongest winds mid aftn onward will be along
the Lake Ontario shoreline. Peak winds after sunset on Thu will be
toward east end of Lake Ontario including Oswego and shoreline up
into Jefferson county. Wind advisories were issued for all these
areas Thu into Thu evening. Areas not in the advisory will see gusts
mid to late Thu aftn up to 40 mph.

There will be some rain showers as well as the front crosses on Thu
but rainfall amounts will be less than 0.25 inch. Exception could be
east of Lake Ontario over higher terrain, but even here, less than a
half inch of QPF expected. Other notable item Thu will be the warmer
temps. Even with the clouds/showers around, warm air advection and a
warm start to the day will result in highs cracking 50 degrees on
the lake plains to the Genesee valley and Finger Lakes. Temps will
stay in the 40s east of Lake Ontario.

Into Thu night, winds diminish and cold air rushes in as sfc low
stays strong but progressive as it lifts to the Canadian
Maritimes while a secondary cold front moves through our
region. Rain showers mix with and change to snow after midnight.
Greatest chances southeast of the lakes boosted by connections
off Lake Huron and Georgian Bay. Marginal temps at H85 -6c to
maybe -9c and also at the sfc in the lower 30s should limit snow
accumulations to less than an inch or two even in the more
favored NW flow lake effect areas.


Cold air advection will continue across the region into Friday. A
northwest wind with 850mb temperatures falling to -11C across the
North Country and -8C across western NY will allow lake effect snow
showers south-southeast of the Lakes. Moisture will be diminishing
quickly while surface high pressure approaches the Ohio Valley. Snow
showers will diminish into Friday evening.

High pressure will track to the south while a weakening area of low
pressure quickly tracks from Lake Superior to Lake Ontario Friday
night. Enhanced convergence and deeper moisture across the North
Country and Tug Hill may result in a period of accumulating snow
especially on the Tug Hill Saturday. An associated cold front will
swing through western and north central NY later Saturday. Breezy
conditions with lake snows behind the front.

Northwest flow weakens as surface high pressure moves overhead
Saturday night. Any snow showers will likely taper off into Sunday

Temperatures will average below normal Friday through Saturday
night. Highs will be around the mid to upper 30s to the low 30s
across the higher terrain.


A change to a meridional flow this period will bring active weather
to our region.

Sunday an upper level trough will deepen over the western Great
Lakes, while zonal flow over the Northeast amplifies. This trough
will deepen a surface low to our west and north...one that the
operational model runs of the GFS, ECMWF and Canadian are in fairly
good agreement with as far as track and deepening the low. Attached
to this deepening surface low will be a cold front, with convective
showers ahead and along it Sunday Night. The cold front will reach
WNY early Monday morning, sweeping across the region through the
day...with post front steeping lapse rates and mixing level heights
supporting strong winds.

Cold air at 850 hPa deepening -10 to -14C behind the cold front
through Tuesday will set the stage for a lake effect precipitation
response, with accumulating lake snows likely Monday afternoon
through Tuesday. Exact placement is still uncertain at this
point...but could include areas northeast of the Lakes, including
Buffalo and Watertown Monday.

High pressure will briefly near the region Tuesday, with winds and
lake snows diminishing, but another storm system Wednesday could
renew the stronger winds along with areas of rain and snow.


Low pressure will pass across Ontario and Quebec late tonight and
Thursday, with a trailing cold front crossing the eastern Great
Lakes Thursday. A few scattered light showers will move across the
area from southwest to northeast tonight, possibly mixing with wet
snow briefly across higher terrain. Most areas will have VFR VSBY,
although a brief period of MVFR/IFR is possible for the higher
terrain east of Lake Ontario. CIGS will deteriorate to MVFR
overnight, with some IFR across higher terrain.

A brief period of more widespread showers will cross the region from
west to east Thursday along the cold front. Areas of MVFR CIGS will
continue, with IFR across higher terrain.

It will become quite windy Thursday, with gusts of 25-35 knots
areawide, and 35-40 knots east of Lake Erie and Lake Ontario for a
few hours around the time of the cold frontal passage.


Thursday night...Areas of MVFR and local IFR. Rain and snow showers
changing to mainly snow showers. Winds diminishing.
Friday...Mainly VFR. A chance of rain or snow showers.
Saturday...MVFR/local IFR. A chance of lake effect snow showers.
Sunday...Mainly VFR.
Monday...Mainly MVFR. Windy. Rain showers changing to snow showers by
late day.


Winds briefly subside into early this evening as sfc ridging slides
across the Lower Lakes. Lingering high waves will keep Small Craft
Advisories up into the early evening on southeast portion of Lake

Moderate to fresh S-SW winds develop throughout the Lower Great
Lakes tonight. A strong, deepening low will move east across Ontario
and Quebec late tonight and Thursday, with a trailing cold front
crossing the eastern Great Lakes late morning and midday Thursday.
SW sustained winds will increase to 30-35 knots with frequent gale
gusts to 35-40 kts. Marginal Gale Warnings have been issued for this
time period. Winds diminish Thu night though higher waves will
linger into much of Fri, especially on Lake Ontario.


NY...Wind Advisory from 7 AM to 7 PM EST Thursday for NYZ019-085.
     Wind Advisory from 1 PM to 10 PM EST Thursday for NYZ005>007.
     Wind Advisory from 10 AM to 7 PM EST Thursday for NYZ001>004-
MARINE...Gale Warning from 7 AM to 7 PM EST Thursday for LEZ020-040-041.
         Gale Warning from 7 AM to 7 PM EST Thursday for
         Gale Warning from 1 PM to 10 PM EST Thursday for LOZ044-
         Small Craft Advisory from 10 AM to 10 PM EST Thursday
         for SLZ022-024.



NEAR TERM...Hitchcock/JLA
LONG TERM...Thomas

NWS BUF Office Area Forecast Discussion