Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 302346
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
646 PM EST Mon Jan 30 2023

.SYNOPSIS...
Notably colder air will move in for the first half of the new work
week with lake effect snow developing tonight through Tuesday east
and southeast of the lakes, with locally moderate accumulations near
the southeast end of Lake Ontario. True arctic air will arrive at
the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...

Widespread light synoptic snows will transition to lake enhanced
snows this evening, favoring locations east and southeast of the
lakes. Colder air will then continue to filter across the region
through much of tonight, with 850H temps down to -18C by daybreak
Tuesday. The combination of lingering synoptic moisture and west-
northwest flow over the warmer Lakes will continue to result in lake
effect snow showers southeast of both Lakes overnight.

Off Lake Ontario...with the longer fetch coming into play we should
see a band of organized lake effect develop tonight east of the
lake, and then move south across Oswego into N. Cayuga and Wayne Co.
That said...where this band eventually finds it final resting spot
is where we may see some modest snowfall totals. Winter weather
advisories have been issued for the previously stated counties
above, which may see snowfall rates of up to 1"/hr and 4-7 inches
along the lakeshore from Wayne to northern Cayuga and into southern
Oswego counties. Lesser amounts will be possible from northern
Monroe and southern Wayne counties with 1-3 inches.

Off Lake Erie...a shorter fetch and drier air working into the mid-
levels will limit lake effect potential. Even so...snowfall
accumulations of 1-3 inches will be possible across the higher
terrain east of Lake Erie, especially along the Chautauqua Ridge.

Otherwise...a weakening wind field on Tuesday will result in lake
snows retreating towards Lake Ontario by the afternoon and then lake
effect snows will end by Tuesday evening. Cold Tuesday with highs in
the teens to low 20s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Our region will be under the strong influence of the northern branch
of a split flow during this period...which will include the coldest
airmass thus far during this winter season. While this pattern will
support some accumulating lake driven snows east of Lake Ontario...
they are not expected to be significant. Outside of possible lake
effect advisories...the only real headlines that could come from the
pending arctic airmass would be wind chill based and not any
organized snowstorms. Breaking this down a bit...

As we open this period Tuesday night and Wednesday...the base of a
longwave trough will be in place over eastern Canada and the Great
Lakes region. A pair of robust mid level impulses passing through
the base of this trough will combine with H85 temps avg -16c to
support some organized lake snows east of Lake Ontario...but the
synoptic environment will not include a lot of moisture and there
will be a limiting cap under 10kt. A west to southwest flow will try
to generate snow showers off Lk erie as well...but that environment
(synoptic moisture/cap) will be even less favorable for anything of
note. Meanwhile...the axis of a large sfc high pressure will be
stretched across our region to insure that MOST of the region
experiences fair mundane weather.

The center of the aforementioned area of high pressure will ease
south of our region Wednesday night...while a strong cold front will
approach the Upper Great Lakes. This will encourage weak warm
advection to start over our region...which will only further weaken
any organized lake response east/northeast of both lakes.

Thursday will then turn out to be the `warmest` day of this forecast
period...if you can think of temps of 30-35 as being `warm`.
Continued warm advection ahead of an approaching cold front will
kill off any residual les off Lk Erie...while only nuisance light
snow showers are expected for sites from about KART north tot he
Thousand Islands. For the rest of us...it should be partly to mostly
sunny (yeah, remember the sun?)...albeit it breezy with gusts in the
vcnty of 25-35 mph.

A strong arctic cold front will then plow southwards across our
forecast area Thursday night. There will be a burst of moderately
heavy snow with the passage of the front along with temperatures that
will plummet from 25 to 30 at nightfall to the single digits by
daybreak. Mercury readings drop to below zero across the North
Country.

Continued cold advection in the wake of the arctic front on Friday
will keep temperatures nearly steady...so that all areas will be in
the single digits except east of Lake Ontario where it will remain
BELOW zero. Snow showers will be fairly common over the western
counties...with lake instability supporting more widespread/somewhat
steadier snow southeast of the lakes (esp. Lk Ontario). Have aimed
well abv guidance for the pops.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A closed upper level low over eastern Quebec Friday night will place
entrance region of the jet in the base of the trough across the
western portions of New York State. Throughout the night, the upper
level low/trough wil pull east and therefore pull the core of the
jet across the region with it. As the low pulls east, strong cold
air will funnel south out of Canada into the Great Lakes. The cold
air won`t linger around for long but will support a couple of days
of frigid weather (Lows Friday night will be in the below zero
single digits across the area south of Lake Ontario, while east of
Lake Ontario will range between 10 and 20 below zero, highs Saturday
will range in the upper teens to low 20s across the area south of
Lake Ontario and mid to upper single digits east of Lake Ontario).
While the cold temperatures are in place, lingering lake effect snows
south of the lakes will hold on in place Friday night before tapering
off early Saturday morning as dry air associated with the arctic
airmass pushes overhead. Additionally, a strong low level jet of
30 to 40 knots will just be exiting the eastern portions of the
forecast area Friday and therefore support some breezy winds. A
combination of the winds and the aforementioned frigid cold
temperatures Friday night will support wind chills to range from
15 to 30 below across the areas south of Lake Ontario and 30 to
40 degrees below zero east of Lake Ontario, likely requiring wind
chill headlines.

The upper level ridge axis lying across the upper Mid-West/western
Great Lakes Saturday will push east, which will support an area of
surface high pressure to slide east across the area as well. This
will cause temperatures to gradually moderate late Saturday and
Saturday night ahead of the next shortwave trough passage. Overall,
Saturday and most of Saturday night will quiet but chilly.

Sunday, temperatures will continue to moderate ahead of a frontal
passage. Speaking of which, a surface low connected with the
shortwave trough aloft will be passing east across Ontario and
Quebec Sunday. As this low passes east, it will drag its cold front
across the area and support a chance for a conglomeration of
precipitation type showers across the area, ranging from snow to a
mix of snow and rain and just rain.

Upper level ridging will yet again build back in across the region
Sunday night and Monday. Initially with the lingering moisture and
cold air in the wake of the low, some lake enhancement/lake showers
will be found east of both lakes. Then with the arrival of the dry
air later Monday snow showers will peter out and leave the area
mostly dry.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Cigs are mainly MVFR to low VFR, with pockets of IFR especially
across the higher terrain areas. Widespread light snow has
redeveloped as a cold front slowly moves southeast through the
region. Snow may cause vsbys to drop below 2SM at times.

The widespread synoptic light snow will transition to lake enhanced
snow southeast of the lakes tonight. The heavy snows are expected to
stay outside of the TAF sites with the exception of KART through
this evening, and KJHW through early tonight. IFR or below conditions
expected within these lake effect bands.

Tuesday, high pressure slowly building into the region will
gradually taper off lake effect snow intensity. The lake effect snow
off Lake Erie should come to an end in the morning hours. The band
southeast of Lake Ontario will persist well into the afternoon,
though will be weakening as it does so. Outside of the lake effect
mainly MVFR to low VFR cigs are expected to persist.

Outlook...

Wednesday...Mainly VFR, except local IFR in lake effect snow east of
Lake Ontario.
Thursday...Mainly VFR, except for MVFR/IFR in lake
effect snow showers east/northeast of Lake Ontario.
Friday...Blustery with MVFR/IFR in lake effect snow showers
southeast of the lakes.
Saturday...Mainly VFR.

&&

.MARINE...
A cold front will move east across the area with increasing westerly
winds bringing SCA criteria winds and waves on both lakes tonight,
especially on Lake Ontario. Winds and waves will be marginal on Lake
Erie and will only remain elevated into early Tuesday morning. On
Lake Ontario, winds and waves will remain at or above SCA criteria
through the morning.

High pressure slowly building in from the Ohio Valley will allow
winds to subside Tuesday afternoon. A weak area of low pressure
passing to our north will then bring a fresh southwest breeze
Wednesday.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 PM EST Tuesday for NYZ004>006.
MARINE...Small Craft Advisory until 7 AM EST Tuesday for LEZ040-041.
         Small Craft Advisory until 1 PM EST Tuesday for
         LOZ042>044.
         Small Craft Advisory from 10 PM this evening to 1 PM EST
         Tuesday for LOZ045.

&&

$$

SYNOPSIS...HSK/RSH
NEAR TERM...AR/PP
SHORT TERM...RSH
LONG TERM...EAJ
AVIATION...AR/PP
MARINE...AR/PP


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