018
FXUS61 KBUF 101123
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
623 AM EST Fri Jan 10 2025

.SYNOPSIS...
High pressure will build in from the west today bringing a day
of dry weather. A weak low pressure system crossing the region
tonight through Saturday will bring a round of light accumulating
snow, followed by some lake effect snow with minor accumulations
Saturday night. High pressure will then ridge into the region
Sunday, bringing fair but chilly weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
Satellite imagery reveals lake clouds persisting southeast of Lake
Erie and Lake Ontario early this morning. High pressure ridge
will build across the region today supporting dry weather.
The lower lake cloud cover may no completely erode before
higher level moisture starts to spill into the region from the
west. Outside of the lake cloud areas, there should be a decent
amount of morning sunshine, before the higher clouds fill in
through the day. It will feel somewhat milder today as we gain a
few degrees from yesterday along with less wind, with most high
temperatures getting into the mid to upper 20s.

The ridge will shift east of the region tonight as a mid level
trough drops into the Great Lakes. This will allow modest moisture
to advect downstream into the region tonight. This push of moisture
will initially work to erode antecedent dry conditions across
western New York, as abundant mid level clouds spread across
the area. 00z guidance a bit slower with the arrival time of the
onset of snow potential into western New York, pending time of
saturation of the column. Snow chances will eventually fill in
across western New york through this evening, pushing into the
Finger lakes and the eastern Lake Ontario region more likely
past midnight. Model melted equivalent looks to be fairly
modest from around 0.15" across far western New York to only a
few hundredths east of the Genesee Valley. Snow ratios around
15:1 giving snow amounts tonight from up to 2" across far
western New York to less than a half inch east of the Genesee
Valley.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
An Atlantic storm system will continue to deepen off the eastern
coast to start the weekend, with cold northwest flow over our region
maintaining light snow over our region. Under an upper level low,
moisture will remain deep, with initial widespread snow
showers...especially over the upslope higher terrain. Accumulations
Saturday up to an inch, with slightly more over the higher terrain.

As the deeper moisture exits our region through the day, this snow
activity will wane through Saturday night, with light lake effect
snow and flurries lingering Sunday morning southeast of the Lakes.

A surface ridge axis will then cross our region later Sunday,
backing winds, and sending these diminishing flurries northward. A
little extra moisture aloft surging eastward may enhancing these
flurries to light accumulating snow east and northeast of Lake
Ontario Sunday afternoon and evening.

These backing winds to southerly, and slight warming aloft may be
enough to send the lake plain to the freezing mark or above...which
may prove to be an infrequent occurrence this month.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The focus this time period will be upon a developing lake effect
snow event off the eastern Great Lakes, an event that could bring
significant snow, especially off Lake Ontario.

A close upper level low at 500 hPa will rotate across the eastern
Great Lakes this period, with the bulk of the deeper synoptic
moisture to the north of the closed low. Temperatures at 850 hPa,
and within this upper level low, will bottom out around -16 to -18C
over our region. This will be plenty cold enough to support
instability for lake effect snowbands to form.

Looking at this event from a climatological standpoint, the
placement of the low at 850/500 hPa over the western Great Lakes
would initially support southwest flow. The forward progression of
this upper low will quickly fit analogs for a western and then
northwestern flow lake effect snow event. A look at CIPS analogs for
the start of this event, the top three events at 00Z/14th
(1/13/2016, 2/10/2008, and 1/30/2009) were all prior lake effect
snow events that reached warning level snow amounts...albeit either
minor warning, or major events, and mainly off Lake Ontario. While
the overall synoptic and thermal patterns may support significant
lake effect snow, a key factor to this event will be the depth of
synoptic moisture...moisture that will strengthen the lake effect
snowbands.

A look at soundings, the moisture depth off Lake Erie will largely
remain around 5K feet or lower, while deeper moisture up to 10K feet
is shown on regional point soundings. This shallower moisture,
especially off Lake Erie may support weaker snowbands, with less
intense snowfall rates. The deeper moisture, and long fetch over
Lake Ontario could bring a heavier snowband to the Tug Hill region.

Light snow Monday as a surface trough swings across the region. Lake
effect snow may begin as soon as Monday afternoon and Monday night
within cold air advection, and rising lake induced equilibrium
levels. The limiting factor will be available deeper moisture for
bands to strengthen. While some moisture increases Tuesday, it will
not be until Wednesday when the upper level low trough axis swings
across our region, wrapping around deeper moisture on a northwest
flow to strengthen the lake effect snow bands. These snowbands will
likely continue, but weaken, into Wednesday night before a surface
ridge axis nears our region for Thursday, supplying a drier airmass
and backing winds that will diminish lake effect snow. But there is
a bit of uncertainty as to how far this surface ridge will extend
into our region...as another shortwave trough may shunt this ridge
to the south...and bring light synoptic snows into our region later
Thursday.

It will become breezy later Monday and through Tuesday as the
surface low passes by to our north and cold air advection tightens
the surface pressure gradient. Northwest brisk winds will linger
into Wednesday along the southern Lake Ontario shoreline.

Monday will start with temperatures near normal, before the arctic
airmass Tuesday through Thursday brings us back to well below normal
maximum temperatures, and near normal minimums.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Lake effect clouds will continue southeast of Lake Erie and Lake
Ontario this morning. MVFR conditions at KJHW, with periodic MVFR
cigs at KIAG/KBUF. Northeast drift to the lake clouds could bring a
short window of MVFR cigs at KROC between 11Z and 14z, but
confidence is low.

A ridge will move overhead today with the lake clouds likely
scattering out as broken cirrus arrives through the day.

Flight conditions will deteriorate tonight as widespread light snow
moves into the region.

Outlook...

Saturday...MVFR/IFR in widespread light snow.

Saturday night...VFR/MVFR with a chance of a few light lake
effect snow showers east of the lakes.

Sunday...VFR.

Monday and Tuesday...Areas of IFR or lower flight conditions
east of the lakes in lake effect snow, with mainly VFR/MVFR
elsewhere.

&&

.MARINE...
High pressure building into the eastern Great Lakes today. This will
result in lessing winds across all marine zones. Still some lingering
elevated northwest winds across the central portion of Lake Ontario
this morning will continue to bring some choppy conditions from
Rochester to Oswego, but overall conditions should remain below
small craft levels. This will allow all small craft headlines
to come down.

A period of elevated westerlies will develop Saturday, but
conditions should remain below small craft levels.

Better chances for marine headlines looks to be Monday and
Tuesday behind the passage of a cold front, as southwest-west
winds strengthen to at least 20 knots with a period of gale
force gusts not out of the question.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...TMA
MARINE...TMA