Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 040232
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
932 PM EST Fri Dec 3 2021

.SYNOPSIS...
Low pressure will pass north of the area Saturday, with lake effect
snow and rain showers developing east of the lakes along with gusty
winds. Lake effect snow east of Lake Ontario may bring minor
accumulations late Saturday and Saturday night. A stronger system
will bring the potential for strong, damaging winds Sunday night and
Monday. Accumulating lake effect snow is possible behind the front
Monday night into Tuesday.

&&

.NEAR TERM /THROUGH SATURDAY/...
High pressure nosing into the area from Ontario will bring partially
clear skies tonight to the North Country. Otherwise lake effect
clouds and a stratus layer trapped beneath the inversion will keep
overcast skies in place from Oswego County westward across Western
NY. A weak passing trough may produce a few scattered light
flurries. A subtle/weak lake response will likely develop for a few
hours tonight. Off Lake Erie, a few light snow showers will continue
east of the lake from the Boston Hills to Wyoming County and the
northern portions of the Southern Tier. A few locations may see a
dusting. A band of snow showers may also develop southeast of Lake
Ontario, likely in northeast Wayne/northern Cayuga counties where a
dusting to an inch is possible locally.

A shortwave trough will drop east southeast across Ontario later
tonight with associated clipper wave passing by to our north through
Saturday. The added synoptic moisture from the clipper system should
be just enough to generate lake enhanced snow and rain showers
Saturday. The best response will be for locations east of Lake
Ontario where 850 mb temperatures will still be cold enough (-8C/-
9C). A few inches of accumulation is possible later Saturday and
Saturday evening for the Tug Hill, with an inch or so for lower
elevations. Some rain may mix in near Lake Ontario. Off Lake Erie,
parameters are not quite as favorable with 850 mb temperatures only
down to (-4C/-6C) and there will be less moisture which doesn`t
extend into the dendritic growth zone. Even so, expect a brief
period of lake effect snow and rain showers northeast of the lake
from mid morning through midday (including the Buffalo area), with a
few leftover rain/snow showers for higher terrain east of the lake
in the afternoon.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Lingering lake snows will taper off late Saturday night, with latest
model guidance keeping the area mainly precipitation free for most
of the day Sunday. The only exception is possibly some light
(mainly) rain showers with a warm front which will lift across the
region during the day. Increasing southeasterly flow will result in
downsloping and a warming trend. Temperatures expected to rise into
the mid to upper 40s across the lake plains west of Rochester by
early Sunday evening.

...STRONG WINDS POSSIBLE SUNDAY NIGHT INTO MONDAY NIGHT...

A 500mb trough will enter the Pacific NW Saturday and deepen as it
travels across the Northern Plains into Sunday. The trough is
progged to take on a negative tilt as it enters the Great Lakes
region Sunday night-Monday. A deepening area of low pressure will
make a similar track across the northern tier of the CONUS crossing
the U.P. of Michigan before it moves towards Quebec Sunday night-
Monday. Ahead of this system, a strong south-southwest low-level jet
will move across western and north central NY Sunday night. A
southeast surface wind will allow strong downslope winds from the
Chautauqua Ridge beginning as early as Sunday evening and off the
northern Tug Hill late Sunday night. These winds could reach 40-
50mph along the Lake Erie shoreline from Ripley to Hamburg and near
the Tug Hill in northern Lewis and Jefferson counties. The rest of
the region will remain in the warm sector with breezy south-
southeast winds with gusts up to 25-35 mph.

A cold front will be charging towards western NY as surface low
pressure continues to deepen to the northwest Monday morning. Strong
cold air advection with strong pressure rises will occur behind the
front as it tracks east across the forecast area. Rain showers will
track across the region along and ahead of the front. Rainfall
amounts of up to 0.25 are possible across far western NY and east of
Lake Ontario. Due to the strong dynamics of this system, a
convective line of showers may accompany the cold front as it tracks
east of the region. There could be an enhanced wind threat if a line
forms.

Models differ in the magnitude of the low-level jet but at least
50kts at 850mb should be overhead as the surface front moves through
the region. Drying and possibly clearing of clouds behind the front
looks better across western NY than the North Country which would
help with the momentum transfer of winds. Southwest winds behind the
front will allow channeling northeast of Lake Erie and Lake Ontario.
This, combined with steepening lapse rates and an isallobaric wind
component increases confidence for high winds from the Lake Erie
shoreline across the Niagara Frontier. Confidence reaching high wind
criteria is slightly lower across the Genesee Valley and east of
Lake Ontario at this time. A High Wind Watch is in effect for
Chautauqua (7PM Sun-9PM Mon), Erie, Niagara, Ontario, and
Genesee (8AM Mon-8PM Mon) Counties. Wind gusts of greater than
58 mph are possible during these time windows. A lesser
magnitude of wind gusts are expected east of this region and
further expansion of the watch or advisories may be warranted.
Also, gusty winds will continue through Monday evening.

Along with the high winds, temperatures will be falling fast behind
the cold front Monday. Highs near 50 will likely be reached in the
morning across western NY and towards afternoon east of Lake
Ontario. Lake effect snow showers will begin east of the Lakes as
winds go from southwest to west across the region. Moisture will be
decreasing  Monday evening and equilibrium levels are progged to be
near 5-8k east of Lake Erie and closer to 10k east of Lake Ontario.
While winds will likely peak Monday afternoon, it will still be
windy going into Monday evening so the combination of winds and snow
showers will produce visibility restrictions on some areas. Best
chance for snow showers will be across the Southern Tier and Tug
Hill region Monday afternoon-Monday night. At this time, minor
accumulations expected. Temperatures will fall to the low to mid 20s
Monday night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A seasonably cold airmass (850Ts -12C to -14C) will remain in place
for the start of this period, with lake effect snow showers
lingering downwind of of the Lakes for a good chunk of Tuesday. High
pressure sliding by south of the area will bring some drier air with
crashing equilibrium levels toward the latter part of the day and
winds becoming more southerly. This will effectively bring any
lingering lake effect to an end as any leftover weakening activity
quickly sweeps south to north across areas downwind of the Lakes.

Attention then turns to the next system that looks to impact the
area later Tuesday night through Wednesday. A longwave trough will
pivot towards the east coast and nudge a warm front into the area,
bringing the next round of widespread precipitation. 12Z guidance
shows the possibility for a weak low to approach from the upper
Great Lakes, bringing the possibility for the chance of a little
light snow across our area Tuesday night. A second, stronger area of
low pressure will track to our south and southeast bringing the
likelihood of a period of light snow to the region with minor
accumulations on Wednesday. This system will exit off the New
England coast Wednesday night with steadier light snows pulling east
of the area.

General consensus is for some warmer and drier conditions to move
into western and northcentral NY for the Wednesday night and
Thursday timeframe. Models solutions then diverge for the end of the
work week, with the potential for the next weather maker to move
into our region to close out the period.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A few minor bands of lake effect snow showers will develop southeast
of Lake Erie and Ontario tonight with local MVFR/IFR conditions, but
this is not expected to impact any of the TAF sites. Otherwise
plenty of clouds will remain in place tonight, with mainly VFR for
lower elevations and MVFR for the higher terrain of the Southern
Tier and western Finger Lakes.

Low pressure will pass to the north of the area Saturday. Lake
enhanced rain/snow showers will develop northeast of Lake Erie from
mid morning through midday, with a brief period of MVFR/IFR possible
including at KBUF. Expect a better, and longer lasting lake response
east of Lake Ontario with areas of MVFR/IFR from late morning
through the evening. Some of this may impact KART, especially midday
through mid afternoon. It will turn windy Saturday, with gusts of 25-
30 knots from late morning through the afternoon.

Outlook...
Sunday...Mainly VFR.
Monday...Mainly MVFR or IFR. Very windy. Rain showers changing to
snow showers by late day.
Tuesday...Local IFR in lake effect snow east of the lakes,
otherwise mainly VFR.
Wednesday...MVFR/IFR. Snow showers likely.

&&

.MARINE...
A fast moving clipper low will move across southern Quebec Saturday,
tightening the pressure gradient in the process. This will bring a
period of moderate to strong southwest/west winds to Lake Erie and
Lake Ontario Saturday through Saturday night. High pressure will
then bring a brief window of light winds Sunday.

A potential gale event is expected in the Sunday night and Monday
time frame with possible storm force gusts.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...High Wind Watch from Monday morning through Monday evening for
     NYZ001-002-010-011-085.
     High Wind Watch from Sunday evening through Monday evening for
     NYZ019.
MARINE...None.

&&

$$

SYNOPSIS...AR/Hitchcock/TMA
NEAR TERM...AR/Hitchcock/TMA
SHORT TERM...Apffel/HSK
LONG TERM...JM
AVIATION...Hitchcock
MARINE...AR/Hitchcock/TMA


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