090
FXUS61 KBUF 281430
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
930 AM EST Fri Feb 28 2025

.SYNOPSIS...
A wedge of high pressure will move through the region early today
with mainly fair weather...but then a deep storm system moving from
the Upper Great Lakes to just north of our area will generate some
widespread snow that will change to rain later this afternoon and
tonight. This event will be impactful for areas east of Lake Ontario
though...as several inches of snow will be likely by late Saturday.
Colder air in the wake of the system will result in a return to cold
weather for the weekend. Temperatures will significantly increase
next week...and this could present flooding concerns from localized
ice jams.

&&

.NEAR TERM /THROUGH SATURDAY/...
Visible satellite imagery showing thickening clouds across Western
NY and the Genesee Valley this morning, with some lingering lake
effect clouds southeast of Lake Ontario in northwest flow. Sunshine
east of Lake Ontario will continue through midday before fading
behind increasing clouds this afternoon.

An anomalously deep (RI 10-20 yrs/late Feb) sub 990mb low over
northernmost Minnesota this morning will track southeast across the
Upper Great Lakes this afternoon...while a relatively narrow wedge
of high pressure and its associated fair weather will quickly exit
our region. This will prompt a tightening baroclinic zone to become
established over the Lower Great Lakes ahead of the approaching
storm system. A 50-60kt low level jet will impinge upon this
steepening thermal gradient to produce deep isentropic leftover
parts of the region later this afternoon and evening...although the
most pronounced forcing will remain north of Lake Ontario (to the
north of the storm track). This low level forcing will be
accompanied by lift being supplied by a 120kt H25 jet that will pass
just south of our region.

The combined lift will result in deteriorating conditions across
our region this afternoon and evening with snow blossoming near Lake
Ontario during the midday and early afternoon. As we progress
through the latter portion of the day...the snow will expand to the
south and east across the remainder of the region while warming in
the low levels will encourage the snow to mix with...then change to
just rain. This changeover will be most pronounced over the western
counties...particularly west of the Finger Lakes. Given the
temperatures will climb through the 30s to near 40 over much of
western New York...it will be tough to get much more than a
coating to a half inch of accumulation. Amounts of an inch or so
will be found over the Eastern Lake Ontario region where the
changeover will be delayed.

The deep area of low pressure will pass by just to the north of
Lake Ontario tonight. This will keep a relatively mild southwesterly
flow in place over the western counties where temperatures should
stay elevated enough to maintain just plain rain showers. While a
southerly push of the mild air will make it to the North country...
there will still be the chance for a mix of pcpn. This could allow
for a few inches of snow accumulation...mainly over Lewis county and
near the Thousand Islands. After midnight though...a cold frontal
passage will usher in notably colder air that will quickly change
the pcpn back to just snow. Temperatures will tumble from the mid
and upper 30s at 4 AM to the 20s in many areas by daybreak. While a
quick icing up could be experienced on untreated surfaces (esp
bridges/overpasses)...brisk westerly winds gusting as high as 35 mph
(mainly far western counties) could help to dry some roadways.

The strong storm system will exit via the St Lawrence valley on
Saturday...while a large sfc high will build across the Upper Great
Lakes. This will produce very brisk west to northwest winds with sfc
gusts to 40 mph producing wind chills in the single digits. Its
certainly worth mentioning that our max temps for the day will be
experienced early in the morning...after which temps will generally
fall through the day. Meanwhile...H85 temps of -18 to -20c will
ignite lake snows off Lake Ontario and to a much lesser degree off a
nearly completely ice covered Lake Erie. This will support likely
pops for lake effect snow showers across the bulk of the region with
some steadier synoptic supported areas of steadier snow across the
North country. Most areas will pick up an inch or two of snow...
with fresh amounts of 3-5 inches expected east of Lake Ontario and
in particular...in the vcnty of the Tug Hill.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
An amplified mid-level troughing pattern centered across the eastern
Great Lakes will gradually shift across the East Coast and into the
Atlantic by Monday due to ridging building east across the Central
Plains and northern Great Lakes. While the trough lies across the
region, a shortwave trough will rotate through its base Sunday
night. Meanwhile, in the lower levels, an area of low pressure will
exit northeast into the Canadian Maritimes Saturday night, will
allow for northwest winds to support cold air to advect into the
eastern Great Lakes. Temperatures at 850mb will drop between -18C
and -20C. As the low pulls east, lake effect snow showers will
continue southeast of both lakes Erie and Ontario Saturday night
through Sunday night. There will be a brief timeframe where lake
snows will weaken, but with the passage of the shortwave trough
Sunday night, lake effect showers will re-intensify.

With the aforementioned building mid-level ridge pushing east Sunday
night and through Monday, surface high pressure will slide east
across the area. As the center of the surface high slides overhead
Monday, dry warm air will act to diminish the lake effect snow
showers. Additionally, winds will veer causing the weakening lake
effect snow to shift north Monday.

Surface high pressure will then reside across the area Monday night,
supporting dry weather.

Outside of the lake effect snow chances, it will be on the cooler
side with temperatures averaging below normal. Lows Saturday and
Sunday night will range in the upper single digits to low teens
south of Lake Ontario, and a few degrees below zero east of Lake
Ontario. On the other hand, highs will mainly range in the teens
Sunday before a warm up Monday with highs in the mid to upper 20s
east of Lake Ontario, and low 30s elsewhere.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
Heading into Tuesday, the next storm system will begin to take shape
over the southern Plains as mid-level trough shifts east of the
Rocky Mountains. This system will rapidly deepen as it phases with a
positively tilted shortwave trough moving south out of the Canadian
Plains. As a result, a rapidly intensifying surface low will track
northeastward from the south-central Plains late Tuesday towards the
Great Lakes by late Wednesday, with the upper level jet ejecting
across the Northeast and Quebec in the process. Still a good deal of
uncertainty in the nature of how the two waves will interact which
will influence the low`s track and strength, though the resulting
surge in temperatures and moisture aloft with strong synoptic scale
forcing should result in widespread rain Wednesday. Boundary layer
temperatures could be just cold enough at the onset Tuesday
evening/night to support a wintry mix in spots across the North
Country. Then, following the widespread rain and warm temps on
Wednesday, much colder air wrapping in behind the system will cause
any precipitation to change back to snow through Thursday.

While the finer details are still murky at this distance, the
combination of temps well into the 40s on Tuesday and low/mid 50s on
Wednesday in combination with the expected soaking rainfall may
warrant some concerns for ice jams on area creeks and waterways
across WNY and/or the North Country. Will need to monitor this
potential with future updates.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Most areas will experience VFR flying conditions through midday...
with the exception of some of the elevated airfields of the Srn Tier
and Finger Lakes where MVFR cigs will persist through midday.

Deepening moisture ahead of the next storm system will then
encourage cigs to drop to MVFR levels late this afternoon with mixed
rain and snow blossoming over the region. The precipitation will
fall mainly as rain over western New York through the first half of
tonight...while some snow may mix with the rain east of Lake
Ontario. VSBYs will drop to IFR levels during the snowfall.

Late tonight...the rain showers will change back to snow. This will
lower vsbys to 2-4SM at times while cigs will be at MVFR levels.

Outlook...

Saturday...MVFR/IFR conditions in snow.
Sunday and Monday...VFR/MVFR with a chance of snow southeast of Lake
Ontario.
Tuesday...Mainly VFR with a chance of rain showers.

&&

.MARINE...
Deep low pressure over the Upper Great Lakes this morning will push
southeast during the midday and afternoon...while a wedge of high
pressure over the region will quickly exit to the east. This will
allow gentle to moderate breezes this morning to significantly
freshen this afternoon and evening.

The sub 990mb (29.2 inches) low will track by just to the north of
Lake Ontario tonight. As a result...fresh southerlies in the
evening will become fresh to strong westerlies by daybreak.
These winds will persist through Saturday...with some gale force
gusts possible over the open waters of Lake Ontario. This will
support widespread small craft advisories that will be in place into
Saturday night...except on Lake Erie where they will subside below
SCA criteria by late Saturday afternoon.

High pressure settling across the Ohio valley on Sunday will produce
moderate west to northwest winds and waves of one to three feet in
ice free areas.

&&

.HYDROLOGY...
We`ve gotten reports of ice movement on Silver Creek, and
Buffalo Creek. This has mainly been in the headwaters where this
ice is not as thick. There also have been no reports of ice jams
causing flooding, since flows are otherwise not that high.

There remains a non-zero flood risk today, so this risk will be
monitored. As temperatures drop below freezing this weekend,
any ice jams will likely lock into place. Ice in the lower and
more populated portions of the Buffalo Creeks remains quite
thick and is thus more difficult to break up.

A system is expected to track to the west of the area Wednesday,
and this will bring much warmer weather and possibly between a
half inch and an inch of rain. This has the potential to cause
ice jams, and possibly creek or river flooding.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 PM EST Saturday for NYZ006>008.
MARINE...Small Craft Advisory from 4 PM this afternoon to 4 PM EST
         Saturday for LEZ040-041.
         Small Craft Advisory until 1 AM EST Sunday for LOZ042.
         Small Craft Advisory until 4 AM EST Sunday for LOZ043-044.

&&

$$

SYNOPSIS...RSH
NEAR TERM...Hitchcock/RSH
SHORT TERM...EAJ
LONG TERM...EAJ/PP
AVIATION...Hitchcock/RSH
MARINE...RSH
HYDROLOGY...Apffel