-- Discussion containing changed information from previous version are highlighted. --
343
FXUS61 KBUF 141858
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
158 PM EST Tue Jan 14 2025

.SYNOPSIS...
Heavy lake effect snow east of Lake Erie and Lake Ontario will
continue through early this evening before a notable southward shift
this evening. Gusty winds will also produce blowing and drifting
snow. Winds will become northwest tonight through Wednesday, with
weaker lake effect snow showers southeast of the lakes. Another
front will cross the area Thursday with light snow showers and areas
of lake enhanced snow east of the lakes. A brief window of dry and
milder weather will then develop Friday through Friday night before
another cold front arrives Saturday, which will usher in a frigid
airmass by early next week.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
...HEAVY LAKE EFFECT SNOW EAST OF LAKE ERIE AND LAKE ONTARIO
THROUGH EARLY EVENING...

Bands of heavy lake effect snow will continue east of Lake Erie and
Lake Ontario through late afternoon or early evening. A sharp mid
level trough along with a surface trough will move southeast across
the eastern Great Lakes early this evening, quickly veering boundary
layer flow to the northwest. Lake induced equilibrium levels will
briefly rise to around 10K feet this afternoon just ahead of the
trough in response to increasing large scale ascent, colder
temperatures aloft, and improved synoptic scale moisture. Inversion
heights begin to drop again tonight following the trough passage.

Wind gusts will continue in the 20-35 mph range through early this
evening before backing off to 10-20 mph overnight and Wednesday,
with diminishing blowing/drifting snow.

Off Lake Erie...

A band of heavy lake effect snow will continue through mid to late
afternoon from far northern Chautauqua County ENE across southern
Erie County into western Wyoming County. Snowfall rates of 2" per
hour will continue in the strongest portion of the band. South of
this main band, a widespread area of light snow will spread east
across the Southern Tier with light snow and minor accumulations.

The trough passage will force the band to move quickly south across
the western Southern Tier and weaken early this evening as flow and
convergence over the lake is disrupted by the rapid wind direction
change. The snow may almost completely fall apart for a few brief
hours this evening. Overnight, lake effect snow will adjust to the
new northwest wind direction and develop again in the form of
upslope snow from the Boston Hills southward to the Chautauqua
Ridge. An upstream connection to Lake Huron will also develop
overnight and meander across the western Southern Tier, locally
enhancing snowfall rates.

Wednesday, the northwest upslope flow will continue, along with
local enhancement from the Lake Huron connection. Snowfall rates
overnight through Wednesday will be much lower than they are today
given the shorter fetch and overall less favorable setup.

Wednesday afternoon, boundary layer flow will begin to back to the
west, carrying lake effect snow showers northward from the Southern
Tier back into southern Erie and Wyoming counties. Boundary layer
flow will continue to back to the southwest Wednesday night,
carrying lake effect snow northward across the Buffalo Metro area
overnight. Inversion heights continue to lower, and synoptic scale
moisture is very limited. This, combined with the rapid northward
movement should keep accumulations limited to 1-2 inches as the band
sweeps north across the area.

Additional accumulations from early this afternoon through the end
of the event will be 6-12" from the Boston Hills and western Wyoming
County southward along the Chautauqua Ridge, with light amounts
elsewhere.

Lake Ontario...

A band of heavy snow will remain over Oswego County and the southern
Tug Hill Plateau through late afternoon or early evening with 2" per
hour snowfall rates. The passage of the trough and associated
veering boundary layer flow will then carry the lake effect snow
south and west across Oswego County and into portions of Wayne and
Cayuga counties from late evening through the overnight. The band
should still be quite strong with the initial southward push through
the evening hours, then weaken overnight across Wayne and Cayuga
counties. Farther west, some lake effect snow will also move into
areas south of Lake Ontario from Rochester westward, possibly
enhanced by a Georgian Bay band late tonight and Wednesday morning.

Wednesday, multiple bands will continue southeast of the lake,
especially from just east of Rochester into Wayne County and
southward into the Finger Lakes. Later Wednesday afternoon and
evening, boundary layer flow will begin to back to the west. This
should allow lake effect snow to consolidate back into a single band
over northeast Wayne and northern Cayuga County.

This band will then move steadily northeast across Oswego County
during the evening, reaching the Jefferson County shoreline up to
Watertown by late Wednesday night as boundary layer flow continues
to back to the southwest. This band of snow may produce another 2-4"
during its trek east and the north along the shoreline. This type of
anticyclonically curved band within a passing low level ridge axis
typically drop their heaviest snow close to the lakeshore, with
little inland extent.

Additional accumulations from early this afternoon through Wednesday
afternoon will be 6-12 inches from the southern Tug Hill Plateau
across Oswego County, and 4-8" across northeast Wayne and northern
Cayuga counties. Farther west, expect a spotty 1-3" from the
Rochester area westward across Orleans and eastern Niagara counties.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
Ongoing lake effect snows will continue to march northward Thursday
morning as wind flow backs to 200-220 degrees across the lakes. Add
to that...lake parameters will become unfavorable with increasing
shear, falling eq-levels, and depleting moisture. So this all spells
a brief break in lake snows but `not` active weather. A vigourous
shortwave dropping across the upper Great lakes will then bring our
next chance for some `light` accumulating snows Thursday afternoon
and through the evening. Nothing significant with a general 1 to 2"
possible for most locales...but areas just east of both lakes will
see some lake enhancement with up to 3 to 4" (Chautauqua ridge and
the Tug Hill region).

After that...weak sfc ridge noses in over the eastern Great Lakes
and will bring drier weather for Friday through Friday night. With
that...southerly flow develops over the region inducing a brief
warming trend (temps rising into the 30s). This doesn`t last long
though...a potent shortwave and `ARCTIC` cold front will near the
eastern Great Lakes Saturday, which will bring increasing chances
for some widespread snow. After that...there is some uncertainty
heading into Sunday with how fast the front marches east, and also a
few waves potentially tracking along this frontal boundary. What is
certain...all medium range guidance advertise what looks like some
of the coldest air arriving across the Lower Lakes this winter
season (H850 T`s -23C to -26C). More on that in the Long Term disco.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
...BITTERLY COLD, WITH THE POTENTIAL FOR ACCUMULATING LAKE EFFECT
SNOWS OFF BOTH LAKES...

While there remains a great deal of details to work out, there is no
question that it will `likely` become bitterly cold. Highs both
Monday and Tuesday will be found in the low teens and even the
single digits. Given some winds anticipated...wind chill values will
more than `likely` be found easily below zero.

Now for the fun...given how cold the airmass will be there will be
some accumulating lake effect snows off both lakes. How much...way
to early at this point to get into the specifics but the signals are
there. One thing to think about...with the anticipated `ARCTIC`
airmass it will potentially begin the process of freezing up the
lakes. This will especially be the case for Lake Erie. Side
note...Lake Erie didn`t freeze last year (2024).
-- End Changed Discussion --

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Heavy lake effect snow will continue through early this evening east
of the lakes with local VLIFR conditions in the heavy snow bands. An
area of general light snow and IFR VSBY will cross the Southern Tier
through early this evening with more widespread IFR, including KJHW.
Outside of lake effect areas, mainly VFR will prevail.

Tonight through Wednesday, boundary layer flow will become
northwest, directing weaker lake effect snow southeast of the lakes
with areas of IFR/LIFR. Lake effect snow off Lake Ontario will be
across the western Southern Tier including KJHW at times. Lake
effect off Lake Ontario will spread out southeast of the lake from
near KROC to KFZY and southward into the Finger Lakes. Outside of
the main lake effect areas, expect areas of MVFR CIGS and light
flurries.

Outlook...

Wednesday night...Lake effect snow east of Lake Erie and Lake
Ontario will move northward overnight, with local IFR.

Thursday...MVFR/IFR with an area of general light snow moving across
the area, and lake enhancement east of the lakes.

Friday...VFR/MVFR with a small chance of snow showers.

Saturday...MVFR/IFR with snow showers likely, possibly mixed with
rain across lower elevations.

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

&&

.MARINE...
Strong westerlies will continue today, with high end Small Craft
Advisory conditions on Lake Erie and Lake Ontario. Winds will become
northwest tonight and Wednesday behind a trough, and start to
diminish. Small Craft Advisory conditions may briefly end Wednesday
afternoon, but winds will quickly increase again Wednesday night
through Thursday as another trough crosses the eastern Great Lakes.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 1 AM EST Thursday for NYZ004-005.
     Lake Effect Snow Warning until 1 PM EST Wednesday for
     NYZ006>008.
     Lake Effect Snow Warning until 4 AM EST Thursday for NYZ012-
     019-020-085.
     Winter Weather Advisory until 7 PM EST this evening for NYZ021.
MARINE...Small Craft Advisory until 4 AM EST Wednesday for LEZ020.
         Small Craft Advisory until 7 AM EST Wednesday for LEZ040-
         041.
         Small Craft Advisory until 7 AM EST Wednesday for
         LOZ042-045.
         Small Craft Advisory until 10 AM EST Wednesday for LOZ043-
         044.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...AR
LONG TERM...AR
AVIATION...Hitchcock
MARINE...Hitchcock