122
FXUS61 KBUF 050233
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
933 PM EST Wed Dec 4 2024

.SYNOPSIS...
Low pressure will pass by just north of the Great Lakes tonight
through Thursday. This system will bring periods of snow and
possibly a few snow squalls, followed by lake effect snow east and
southeast of the lakes which will last through Friday night. Winds
will also be quite strong, with blowing and drifting snow causing
difficult travel conditions late tonight through Thursday night.
There will be some accumulating snow at all areas, but the greatest
snow amounts will be across the higher terrain east of Lake Erie and
Lake Ontario.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
General light snow associated with mid-level warm air advection
across the eastern Lake Ontario region this evening will continue to
lift north into the Saint Lawrence Valley tonight. This will bring
some general light snow and minor accumulations less than 2 inches.
Otherwise, it`ll be windy this evening with gusts to 40 mph
resulting in limited areas of blowing snow.

Tonight, light warm advection and upslope snow will continue east of
Lake Ontario this evening. A strong cold front will then move across
the area from west to east tonight. This will be preceded by a weak
front/trough which will light snow to push into far Western NY ahead
of the main cold front. However, the stronger front will capture
this band and produce an initial band of heavy snow within the next
hour or two. With this band, expect a quick burst of heavy snow
(snowfall rates of up to 2 inches per hour). Aforementioned squall
will move across the remainder of the area overnight. In addition,
westerly winds will pick up following the frontal passage,
potentially producing some snow squalls as it moves through. After
the first squall, subsequent squalls will have a lesser intensity
however will continue to produce hazardous driving conditions. The
last of the squalls looks to pass across the Buffalo Metro region
near the morning commute (around 7am). Meanwhile, east of Lake
Ontario, upslope snow will increase tonight across the southern Tug
Hill, and lake enhanced snow will develop first across the Thousand
Islands region overnight, then move south to the Tug Hill Plateau by
Thursday morning.

Thursday, boundary layer flow will veer from west to northwest
through the day. Expect areas of upslope and lake enhanced snow east
of the lakes, along with narrow meandering bands of briefly heavy
lake effect snow from Lake Huron, Lake Erie, and Lake Ontario across
much of the region. Snow will be moderate to heavy at times, with
snowfall rates in the 1-2 in/hr in most persistent bands.

In addition to snowfall, it will become very windy as the surface
low passes just north of the area. Following the frontal passage,
gusty westerly winds will become widespread Thursday. Winds will
gust 35 to 45 mph and up to 50 mph along the Lake Erie and Lake
Ontario shores and across higher terrain. This will result in
considerable blowing and drifting snow which will hinder snow
removal operations and produce poor visibility which will make
travel difficult. Blowing snow will likely be the greatest impact
from this storm.

Thursday night a more west-northwesterly to northwesterly flow will
help to direct increasingly multi-banded lake snows across areas
southeast of the lakes. Elsewhere lingering synoptic and
orographically-driven snow showers will tend to gradually become
more scattered as the mid and upper levels slowly dry out. Otherwise
winds will slacken and lead to a welcome reduction in the amount of
blowing snow compared to during the day Thursday.

For most areas, the bulk of the accumulating snow from this event
will occur late tonight and Thursday with more localized
accumulations Thursday night. Storm totals will range from 14 to 22
inches across higher terrain east of the lakes where warnings are in
place. Moderate storm total accumulations of 6 to 10 inches in
northern Erie County, Genesee, and Allegany counties, with a general
3-6 inches elsewhere.

No change to winter headlines on this update. This event is a mix
between synoptic and upslope followed by lake enhancement east of
Lake Erie so there is a Winter Storm warning there, while there are
Lake Effect snow headlines elsewhere. Amounts are generally below
Advisory criteria in the Genesee Valley and western Finger Lakes,
but impacts from blowing snow justify the advisory.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
During Friday the cold northwesterly flow will gradually become more
westerly again as a shortwave and attendant weak surface trough
rapidly drop southeastward from the Upper Great Lakes...with the
surface trough then getting left behind and lingering in place
somewhere near/over Lake Ontario through Friday night. While
moisture will initially be more limited Friday morning, the
aforementioned shortwave will help bring an increase in mid-level
moisture again Friday afternoon and evening. Coupled with the
gradually increasing fetch and lake equilibrium levels still running
in the 8-10 kft range, this should allow for another uptick in the
lake snows east-southeast and then east of the lakes Friday
afternoon into Friday evening. Then models hint at a Lake
Superior/Georgian Bay moisture connection enhancing snows southeast
of Lake Ontario late Friday night into Saturday morning. This has
the potential to produce 6 inches or so of additional accumulation
from Wayne to Oswego counties, and may require additional lake
effect headlines there if forecast confidence increases. Snow will
continue east of Lake Erie as well, with additional snow
accumulations there as well.

Outside of the above areas, it will be notably less windy with some
scattered snow showers at times and some localized minor
accumulations in spots. Otherwise temperatures will remain below
average with highs Friday ranging through the 20s.

Warm air advection will then increase across our area Saturday and
Saturday night. This will push lake effect bands northward, however
lowering inversions due to the warm air advection will cause snow to
be less intense with only minor accumulations across the Niagara
Frontier and across the North County. Temperatures will start an
upward climb with highs Saturday in the upper 20s/lower 30s, and a
non-diurnal temperature trend then following for Saturday night. By
late Saturday night any lingering showers may be mixed with rain.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A reprieve from winter for much of this period with above normal
temperatures and a soaking rain to start the work week. A cold front
will approach toward the latter half of the work week that will
eventually bring a return to colder temperatures, however exact
timing of the boundary still remains in question this far out.

A warm front will be slowly moving northeastward through the eastern
Lake Ontario region as we open the period on Sunday. This will keep
the likelihood of snow showers going Sunday morning east of Lake
Ontario, before the boundary slows or stalls across far northern NY.
This will allow some scattered activity to continue through Sunday
afternoon, with rain showers becoming the predominant p-type aside
from the Tug/western Dacks as warmer air continues to make inroads
into the North Country.

A few showers linger into Sunday night before a strengthening cutter
system moves northeast through the western Great Lakes to start the
new work week. Deep southwesterly flow on the eastern flank of this
system will bring a surge of warmer air along with a slug of deeper
moisture into our area Monday, setting the stage for a soaking
rainfall to start the work week, with steadier rain possibly
lingering into at least a portion of Monday night. Exact timing and
placement of the heaviest rainfall axis still in some question as
model consensus still differs some on exact track of the low
pressure system.

Plenty of lingering moisture along with ill-timed pieces of
shortwave energy within the cyclonic flow aloft will keep at least
on and off showers going through the day Tuesday, however with above
average temperatures remaining in place, these showers will remain
in the liquid form.

Higher uncertainty then creeps in toward mid week with regard to the
timing of a cold frontal passage. The main discrepancy appears to
lie with the timing of the development of a frontal wave along the
boundary, which would slow eastward progression. At this point,
solutions range from a cold fropa as early as late Tuesday, to as
late as Wednesday afternoon, with some disagreement as to how fast
the colder air moves behind the boundary as well.

Rainfall amounts tough to pin down at this range, however combined
with snow melt, this will likely cause at least some rises on area
creeks, streams, and rivers. However, where the snowpack is deep it
will not be ripe and will soak up some if not all of that rainfall,
with lighter on and off rain showers and above average temperatures
lasting through at least Tuesday. Combine this with our dry
antecedent conditions, and the risk for widespread flooding remains
low at this time, but will need to be monitored going forward.

As for temperatures, highs ranging from the mid 30s to low 40s
Sunday will gradually rise to the mid 40s to low 50s by Tuesday.
Temperatures then become more uncertain heading into mid week
depending on the timing of the aforementioned cold front.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Warm front exiting north out of the eastern Lake Ontario region this
evening will continue to exit north into the Saint Lawrence Valley.
This has supporting CIGS to lift temporarily to VFR. VFR CIGS are
also across KROC this evening, while MVFR/IFR CIGS are found across
WNY as the next round of snow begins to near the far western portion
of the region. Windy conditions will continue with 20-30 knot SSW to
SW gusts for most, although 30-35 knots for KBUF/KIAG. These winds
will be strong enough across western NY to cause some residual
blowing snow, however no major impacts expected for the next couple
of hours.

The snow will become more widespread tonight as strong Clipper
system moves by just to the north of our area, while also dragging a
strong cold front from west to east across the region. Mainly MVFR
CIGS expected areawide tonight, with a brief period of IFR CIGS
possible with the frontal passage. Staying with the frontal passage,
the most impactful weather tonight will be along and just ahead of
this strong cold front as it crosses the area. Expect a period/burst
of moderate to heavy snow with the boundary along with blowing snow
driven by SW to W winds gusting 20-30 knots for most areas, with
again 30-35 knot gusts possible closer to the lakeshores. With this
in mind, expect mainly IFR/LIFR VSBYs tonight, with VLIFR possible
at times. Timing of worst impacts will be mid/late evening through
the middle of the overnight across western NY, to late tonight
through the first part of Thursday morning east of Lake Ontario. In
addition, expect a general uptick in widespread light snow as well
with the Clipper system passing by just to the north. This will
likely keep VSBYs down into the MVFR to IFR range even outside of
the heavier snows associated with the frontal passage, especially
when you add in areas of blowing snow developing later tonight.

The Clipper system and associated strong cold front pull east of the
area Thursday with main areas of snow becoming more lake effect and
upslope dominant, thus more localized in nature. This will keep the
heavier snow confined mainly to the higher terrain (KJHW) east and
southeast of both lakes Thursday. With that said, there will still
be impacts even in locations where snow may not be falling due to
areas of blowing snow likely continuing across the entire area as
winds strengthen even further. Expect widespread W wind gusts of 30-
35 knots, with 40-45 knots possible close to the lakeshores and
across the hilltops. CIGS will remain mainly MVFR Thursday. The
larger impacts will likely be from low VSBYs as a result of falling
and blowing snow, although they will be highly variable, ranging
from IFR/LIFR at times where snow is falling, to MVFR/VFR to
intermittent IFR where blowing snow is predominant.

Outlook...

Thursday night...Mainly VFR with scattered snow showers. Heavier
lake effect snow southeast of the lakes with local IFR/LIFR.
Continued breezy to windy with some areas of blowing snow.

Friday...VFR/MVFR with scattered snow showers. Localized IFR in
lingering lake effect snow showers southeast of the lakes.

Saturday...VFR/MVFR with a chance of snow showers.

Sunday...Mainly VFR.

Monday...MVFR/VFR with rain.

&&

.MARINE...
Moderately strong low pressure will pass just north of the lakes through
early Thursday before a secondary coastal low deepens over the
Canadian Maritimes Thursday night. Near gale for SSW winds today
will become more westerly late tonight and Thursday as the low
passes by, with the best chance of more widespread gale force
winds coming Thursday on both lakes. Gale Warnings remain in
effect for Lake Erie and Lake Ontario. Small craft headlines in
place for the Niagara River and part of the St. Lawrence River.

Winds drop off some on Friday, but the westerly flow is still
likely to require a period of small craft headlines following
the gales. Winds drop off briefly Saturday as a narrow ridge
passes by, then southwesterly winds pick up behind it Saturday
night.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 AM EST Friday for NYZ001-002-
     010-011-021.
     Winter Weather Advisory until 4 AM EST Friday for NYZ003>005-
     013-014.
     Winter Storm Warning until 4 AM EST Friday for NYZ006>008.
     Lake Effect Snow Warning until 4 AM EST Friday for NYZ012-085.
     Lake Effect Snow Warning until 4 AM EST Saturday for NYZ019-
     020.
MARINE...Small Craft Advisory until 1 AM EST Friday for LEZ020.
         Gale Warning until 7 PM EST Thursday for LEZ040-041.
         Small Craft Advisory until 1 AM EST Friday for LOZ030.
         Small Craft Advisory until 4 AM EST Thursday for
         LOZ042>045.
         Gale Warning from 4 AM Thursday to 1 AM EST Friday for
         LOZ042>045-062>065.
         Small Craft Advisory until 7 AM EST Thursday for
         SLZ022.

&&

$$

SYNOPSIS...Apffel/Hitchcock
NEAR TERM...Apffel/EAJ/Hitchcock
SHORT TERM...Apffel/JJR
LONG TERM...JM
AVIATION...EAJ/JM
MARINE...Apffel/Hitchcock