Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 180755
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
355 AM EDT Mon Mar 18 2024

.SYNOPSIS...
Cold air will deepen across the region this week, with several
passing surface troughs producing occasional rounds of snow showers,
graupel, and lake effect snow through Thursday. The greatest snow
accumulations will be found across the higher terrain east of Lake
Erie and Lake Ontario. The snow will most readily stick from around
sunset through mid morning each day, with some melting during the
daylight hours due to the high March sun angle. Temperatures will
run below average through the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Continued cold air advection will drop 850 hPa temperatures to -10C
by daybreak to allow for lake effect snow to continue to develop.
Temperatures aloft may actually warm a degree or two today, and with
the steepening March sun angle, any organization to the lake snows
will deteriorate to more cellular in nature as deep diurnal mixing
interferes with the delicate circulations that drive bands of lake
effect snow. This will hold back on snow accumulations to some
extent. Expect a spotty inch or so for the higher terrain east of
Lake Erie and 2-4" for the Tug Hill Plateau.

By tonight...synoptic moisture will have deepen sufficiently that
with strong CAA aloft and steepening lapse rates lake effect snow
should once again increase in intensity east of both Lakes. The
approach of a secondary surface trough from Canada will enhance low
level convergence with greater snow accumulations east of Lake
Ontario than east of Lake Erie where some wind shear will allow the
snow bands to oscillate. East of Lake Erie additional snow should
amount to 1 to 3 inches, while additional snow amounts of 4 to 6
inches are possible on the Tug Hill.

A shortwave trough will approach the region on the backside of a
departing trough Tuesday. Boundary layer flow will back to the
southwest and will likely cause ongoing lake effect snow showers to
move north towards the Northtowns east of Lake Erie and the Tug Hill
east of Lake Ontario. Warm air advection will take place ahead of an
approaching surface low pressure/surface trough. While lake induced
instability will become marginal east of Lake Erie by Tuesday
afternoon, forcing from the surface low and approaching trough will
intensify snow showers across the region. Daytime highs will reach
the upper 30s to low 40s and any snow accumulation will likely be
confined to the higher terrain east of the Lakes. Breezy conditions
will result in wind chill values in the 20s Tuesday.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Convective snow showers Tuesday evening will diminish in coverage
and then transition to a more pure lake effect regime. Some light
accumulating snow will be possible again in the most persistent
snows. Lows will generally be found in the 20s.

A potent shortwave dropping southeast through the broader trough
Wednesday is advertised to bring a re-enforcing shot of colder air.
we should see a fairly significant up-tick in snow showers activity
in the afternoon with some of the stronger cells capable of
producing graupel at times. This is supported with BUFKIT profiles
showing steepening lapse rates of 8-9 C/km. It will also become
quite breezy with winds gusting up to 35-40 mph. Snowfall
accumulations will `likely` remain on the light side but some
locales may squeak out a few inches in the more intense snow shower
activity. Highs will be found in the 30s across the region.

Wednesday night...drier air gradually working into the eastern Great
Lakes will bring about an overall decrease in snow shower coverage.
However...there will still be some limited lake effect snows to
contend with off the lakes. Anticipating a cold night with lows in
the teens and 20s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Winter like pattern for at least the start of the long term period.
While the long term period won`t be as cold as some days we have had
this winter, it will be among the coolest vs climatology, especially
for Thursday where afternoon highs of 10 to 15 degrees below normal
are expected for most of the area. Temperatures in the mid 20s to
mid 30s for the day on Thursday will slowly warm on Friday to the
upper 20s to low 40s. Still plenty of uncertainty with the weekend
among the guidance and therefore the weekend temperatures, but new
guidance is starting to come in colder, so will take that into
account for the weekend Max Ts and adjust them down some.

Models seem to be in fairly good agreement that lingering lake snow
showers will continue into Thursday south and southeast of the
lakes, tapering off through the day. Thursday afternoon and most of
the night dry out as a weak ridge and quick sfc high pass by before
another batch of showers approach.

A weak warm front tracking across the area brings the next chance
for snow showers (mixing with rain at times) Friday morning, with
the trailing cold front/trough continuing the precip into the
morning on Saturday.

There will be the potential for a lake response off of both lakes
from Saturday morning into Saturday night, but model disagreement
becomes more evident from Saturday morning onward. The GFS brings a
colder airmass with 850H temps dropping to -12 to -18 C for
Saturday, while the Canadian is much warmer only dropping the 850H
temp to around -9C briefly. This is in part because the Canadian
also places the main portion of the mid-level trough and low farther
north and looks to move the main trough through quicker.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
Cold air aloft will continue to support increasing lake effect snow
east of Lake Erie and Lake Ontario. Strong diurnal mixing from the
high March sun angle though will likely break apart the lake effect
snow into convective snow showers from late morning through early
evening, with any of the heavier snow showers producing brief/local
IFR/LIFR VSBY and MVFR CIGS. Outside of lake effect areas, general
snow showers will increase Monday afternoon with local IFR as a
trough and deep moisture cross the region.

CIGS of 2500-3500 ft with scattered snow showers can be expected
tonight with lake snows supporting IFR VSBYS in areas east of both
lakes.

Outlook...

Tuesday through Wednesday...Occasional lake effect snow showers with
local/brief IFR conditions. MVFR/VFR outside of lake effect.

Thursday...MVFR/VFR with a chance of snow showers and associated
brief/local IFR.

Friday...Mainly VFR.

&&

.MARINE...
Small craft advisories are in place throughout the Lower Great
Lakes...as a deep cyclonic flow will maintain fresh to strong winds
through at least Monday evening. During this period...gale force
gusts will be possible on the eastern half of Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 5 AM EDT Tuesday for NYZ006>008.
MARINE...Small Craft Advisory until 8 PM EDT Tuesday for LEZ040-041.
         Small Craft Advisory until 8 PM EDT Tuesday for
         LOZ042.
         Small Craft Advisory until 5 AM EDT Wednesday for
         LOZ043>045.

&&

$$

SYNOPSIS...Hitchcock/Thomas
NEAR TERM...Hitchcock/HSK/RSH
SHORT TERM...HSK
LONG TERM...SW
AVIATION...Hitchcock/RSH
MARINE...Thomas


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