997
FXUS61 KBUF 121457
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
957 AM EST Wed Feb 12 2025

.SYNOPSIS...
Low pressure will move into the Ohio Valley late today, then pass
directly over the eastern Great Lakes tonight and early Thursday.
Light snow will quickly overspread the area from southwest to
northeast late this afternoon, with the snow rapidly changing to a
wintry mix, and then to rain in most areas tonight. Rain
showers early Thursday will change back to snow showers as much
colder air pours back into the region, with accumulating lake
effect snow east and southeast of Lake Ontario and Lake Erie
late Thursday through Friday.

&&

.NEAR TERM /THROUGH THURSDAY/...
Dry weather will prevail through early afternoon, with plenty
of clouds in Western NY, and some partial sunshine east of Lake
Ontario.

A southern stream shortwave will phase with a northern stream
shortwave moving along the US/Canadian border, with the resulting
mid level trough moving across the Great Lakes into western Quebec
tonight through Thursday. A surface low associated with the southern
stream shortwave will reach the Ohio Valley this evening, then track
directly across the lower Great Lakes, likely just on the Canadian
side of the border overnight. This low track will allow warmer air,
first aloft, and then at the surface, to spread into our region,
resulting in a complex precipitation type forecast. While this
system will produce a myriad of weather including snow, ice, and
wind, impacts from all of the above will be minor.

Increasing warm advection and moisture transport will allow light
snow to develop across Western NY mid to late afternoon, then spread
rapidly into the eastern Lake Ontario region by early evening. A
strong push of warm advection ahead of the surface low, aided by
downsloping off the Allegheny Plateau, will bring a significant warm
nose aloft rapidly into the area this evening, changing the snow
over to a period of sleet and freezing rain. Surface temperatures
will surge above freezing just a few hours after the arrival of the
warm nose aloft, changing precipitation to rain overnight in most
areas. The rapid warming will keep snow and ice accumulations very
minor in most areas, with a few exceptions noted below.

Low level northeast flow will hold cold air in a little longer
across Niagara and Orleans counties, resulting in a slightly longer
period of both snow and ice this evening. Some of the more sheltered
valleys of the Southern Tier will also hold onto the low level cold
air longer, allowing for a few extra hours of freezing rain.

Across the North Country, precipitation will remain snow a little
longer with a slower arrival of warm air aloft, especially close to
the Saint Lawrence River, where precipitation may stay snow most of
the night, with only a brief changeover to a mix for a few hours
Thursday morning.

As far as accumulations go, expect 1" or less of snow accumulation
for the majority of the area. Niagara and Orleans counties may see 1-
3", and most of the North Country may also see 1-3". Right along the
Saint Lawrence, expect 4-6" of accumulation. Ice accumulation will
be very light, on the order of a few hundredths of an inch in most
locations. There may be up to 0.10" of ice in some of the Southern
Tier Valleys, Niagara and Orleans counties, and across the Tug Hill
region 0.10" to 0.20" in some spots. Any ice that accumulates
will quickly melt off overnight as temperatures rise above
freezing.

Thursday, the surface low will move down the Saint Lawrence Valley,
with a strong cold front sweeping from Western NY at mid morning to
the eastern Lake Ontario region by early afternoon. Colder air
pouring back into the region will change rain back to snow, and
bands of lake effect snow will begin to develop during the afternoon
east of Lake Erie and Lake Ontario. Expect minor accumulations
through the day.

Finally, winds will become quite gusty tonight through Thursday. A
strong 50+ knot SSW low level jet will cross the eastern Great Lakes
tonight. A favorable low level inversion and stable layer near the
hilltops will allow for downslope winds to develop in the typical
locations, including the Lake Erie shore, Finger Lakes, and along
the north slopes of the Tug Hill Plateau. Gusts may reach 40-50 mph
at times. Winds will increase out of the west and southwest Thursday
behind the cold front, with gusts in the 35-45 mph range.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Behind the departing low, CAA ramps up sending H850 T`s down to
-16C to -18C across the Lower Lakes by Friday morning. All the
ingredients are coming together with deep moisture, EQL surpassing
9K feet, and well aligned flow (WNW) which will support accumulating
LES, especially off Lake Ontario. Lake snows begin to become more
organized Thursday evening east of the Lake Ontario as colder air
rushes into the region. As flow becomes more NW`erly lake snows will
then settle south Thursday night across S. Oswego and N. Cayuga,
possibly even making it into parts of Wayne County. Given upstream
priming and overall model consistency, confident that we will see
significant accumulations. Have issued a Winter Storm Watch for LES
beginning 00Z Fri thru 03Z Sat.

Off Lake Erie...a bit of a different story will unfold but it is
`not` out of the question that we could see decent accumulating
snows. The bigger `unknown` is how much `ice` is covering the lake
and how it will impact LES. Some guidance suggest that we may see a
brief window of LES or a band form. Looking at Bufkit sounding
profiles EQL do climb briefly up to 9k, and moisture extends well
through the DGZ Thursday evening through the first part of the
night. After that...high pressure builds in and EQL levels fall
which will begin to limit the extent of the lake response. That
said...we could see some locales pick up several inches or even
high end advisory amounts. Again it will all depend on how much
`ice` coverage there is. For now will continue to mention the
potential for accumulating snows in the HWO.

While lake snows wrap up fairly quickly off Lake Erie Friday
morning, lake snows will continue off Lake Ontario through atleast
Friday afternoon. It will not be until Friday evening that lake
snows off Ontario wrap up or become negligible. This will occur as
drier air filters into the region and the environment becomes
unfavorable.

Other than some lingering flurries or light snow showers east of
Lake Ontario, quiet weather is expected Friday night ahead of the
next system. High pressure overhead quickly gets kicked out
Saturday, with low pressure bringing in our next area of light snow
from the west. Widespread light snow will work across the entire
area from west to east with a general 2-4" across Lower Lakes
Saturday.

No rest for the weary...on the heals of this weak low pressure
system, a stronger low will potentially bring another round of
accumulating snow or even a wintry mix. More on that in the long
term disco.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
A potentially stronger low pressure system Saturday night-Sunday
will follow the weaker low. A plethora of precip types will be
possible with this system and will be contingent upon the exact
track, which may be `a lot` closer to our region. Best chances for
all snow will be across the North Country, with a mixed rain/snow
toward the NY/PA line. Latest model guidance suggests that the
stronger wave will pass either just southeast of our area or
possibly right across our area late Saturday night through Sunday,
with the likelihood for a fairly strong surface low (sub 990 mb)
moving from the Ohio Valley to the Northeast. This second wave has
the potential to produce heavy snow or a mix of rain and snow if the
system tracks right across our area, especially with a stronger low
having the potential to advect in even warmer air from the south.
This will also have the potential to bring some stronger winds to
the region, the degree to which will also be tied to the track of
the low.

Bitterly cold airmass accompanied by some gusty winds then set to
pour across the lower Great Lakes region and Northeast for the first
half of the new work week. Expect highs in the single digits and
teens, with lows ranging from the mid single digits to below zero
across the higher terrain. Would not be surprised if cold weather
headlines are eventually needed for a least a portion of our area
during this timeframe. As an added bonus, there will also be the
potential for accumulating lake snows east and southeast of the
lakes.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
Low pressure will then move into the Ohio Valley this evening,
before reaching the west end of Lake Ontario by daybreak
Thursday. An area of light snow will overspread the area quickly
from southwest to northeast late this afternoon, then change to
a brief period of wintry mix before changing to all rain in
most areas tonight. For most of the region, expect only very
minor amounts of snow and ice with only minor impacts.
Precipitation will stay snow, and then ice, a little longer for
the North Country, including KART. CIGS will deteriorate to
MVFR/IFR shortly after the onset of precipitation late today,
with lower CIGS lasting through the overnight in most areas.

It will turn quite windy tonight, especially across higher terrain
and in downslope areas from the Southern Tier into the Finger Lakes
and North Country, with gusts of 30-40 knots out of the south. There
may be also be some low level wind shear at times when surface gusts
drop off, as a 50+ knot SSW low level jet crosses the eastern Great
Lakes.

Outlook...

Thursday...Rain showers changing back to snow showers with MVFR
local IFR conditions. Windy.

Thursday night...IFR in lake effect snow SE of lakes, otherwise
VFR/MVFR with scattered snow showers..

Friday...VFR/MVFR with a chance of snow showers. Local IFR in
lake effect snow southeast of Lake Ontario.

Saturday and Sunday...IFR/LIFR in snow.

&&

.MARINE...
Low pressure will move into the Ohio Valley this evening, then reach
the western end of Lake Ontario by early Thursday morning before
moving down the Saint Lawrence Valley Thursday afternoon. East to
northeast winds will continue to increase on Lake Ontario today
ahead of the system, producing high end Small Craft Advisory
conditions on the west half of the lake.

The easterly winds will swing around to southerly tonight as the low
approaches, then become westerly Thursday following the passage of
the associated strong cold front. Winds will quickly increase
Thursday, with gale force winds likely on Lake Ontario in the
afternoon and evening, with sustained winds of 25-30 knots on Lake
Erie. Winds will gradually diminish later Thursday night through
Friday.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 1 PM this afternoon to 4 AM EST
     Thursday for NYZ001-002-010>012-019>021-085.
     Winter Weather Advisory from 4 PM this afternoon to 4 AM EST
     Thursday for NYZ003>006-013-014.
     Winter Storm Watch from Thursday evening through Friday
     evening for NYZ005-006.
     Winter Weather Advisory from 7 PM this evening to 7 PM EST
     Thursday for NYZ007-008.
MARINE...Small Craft Advisory until 4 AM EST Thursday for LOZ042>044.
         Gale Watch from Thursday morning through Thursday evening
         for LOZ042>045-062>065.

&&

$$

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