Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 182359
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
759 PM 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/...
Light to moderate snow across portions of the area, especially along
the I90 corridor east of Buffalo where brief drops in visibility to
around a half mile or so will be possible. This uptick in snow is
occuring along the cold front as it drops southeast across the area.

A weak shortwave ripple and associated cold front to the north will
sag southward through the area this evening. While this will bring
some reinforcing cold air (back down to around -12C), and the lack
of sunlight will encourage better organizing lake snows...BUFKIT
soundings indicate a brief drying of the DGZ within this colder
airmass overnight and with a WNW flow prevailing, expecting the lake
effect activity (especially off Lake Erie) to be rather weak and
scattered in nature after the cold front passes through the area.
That being said, sfc temps dipping into the 20s across the region
will allow any additional snowfall to better stick to the grassy
areas and untreated roads overnight. Spotty additional accumulations
of an inch or so possible across much of the area east of Lake Erie,
with an additional 2-4" across the Tug Hill.

Late tonight into Tuesday morning another shortwave trough will
swing through the region from the west. This will cause the low-mid
level steering flow to back from WNW to SW with additional
saturation through the DGZ. Lake snows as a result will somewhat
organize and be redirected east-northeast of the lakes including
into the Buffalo Metro area by late Tuesday morning. By this point
however deep diurnal mixing from the mid-March sun will likely cause
this band to become relatively cellular in nature, and temps warming
aloft behind the shortwave will cause EQLs to lower to around 6-7k
feet, again limiting potential accumulations to around an additional
inch or so northeast of Lake Erie with minor spotty accumulations
elsewhere. Greater fetch over Lake Ontario should allow for another
1-3" depending on how quickly the band lifts northward. Sfc temps
Tuesday will be similar to today, perhaps a few degrees warmer
though blustery winds will lead to wind chills solidly in the 20s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
Upper level trough with cold air advection will remain through this
period, generating lake effect snow downwind of the Lakes. Diurnal
effects of the higher March sun angle will limit snow totals through
the daylight hours, with snow bands becoming disorganized and
cellular.

Marginal temperatures aloft of -8 to -9C at 850 hPa Tuesday night
will bring lake effect snow east of the Lakes. Snow around an inch
or so east of Lake Erie, with initially deeper moisture over Lake
Ontario leading to two to three inches of snow on the Tug Hill.

An mid level shortwave will pass across the region later Wednesday,
with stronger cold air advection behind it. Scattered snow showers
during the day Wednesday, in addition to localized lake effect snow,
yet accumulations will range from a coating across the lower
terrain, to an inch or two across higher terrain east of the Lakes.

The stronger cold air advection will briefly increase lake effect
snow parameters east of the Lakes Wednesday night, however fleeting
synoptic moisture will not allow for much band development. Could
see 1-3 inches east of Lake Erie Wednesday night, and 2 to 4 inches
east of Lake Ontario.

The diminishing moisture Thursday will allow for bands of snow
southeast of the Lakes to fade to flurries through the afternoon
hours.

It will be blustery at times this period, especially Wednesday and
Wednesday night with the passing of the mid level shortwave. Gusts
to 35 mph are likely near the Lakes. These winds could bring some
limited blowing snow on the Tug Hill Wednesday night.

Below normal temperatures continue this period, especially on
Thursday when despite increasing amounts of sunshine, daytime
temperatures will struggle to rise above the freezing mark.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The upper level low will slowly exit our region to begin this
period, but the jet stream will remain active. Friday a possible
phasing of the northern and southern branch of the jet may yield a
developing synoptic system over our region. This system may develop
over or to our east, and with the models struggling with phasing
this winter will not place high confidence in the storm as of yet.
If the storm does develop, accumulating snow, especially Finger
Lakes eastward is possible.

Lake response behind this system looks to be brief, possibly into
Saturday as heights increase aloft through the weekend. Another
storm system ejecting out of the Rockies late in the weekend may
bring a mix of snow changing to rain Monday along a warm front.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Cold air within a deep overhead trough will continue to flow over
the lakes, supporting lake effect clouds and snow showers across the
region through Tuesday. Cigs within these lake effect clouds are
mainly MVFR between 2-3k feet, but some reductions to IFR at times.
The steep March sun angle will cause lake snows to remain
disorganized through early evening, though brief localized IFR vsbys
are possible especially in heavier bursts of snow and near the
higher terrain east of Lake Ontario where orographic lifting is
playing more of a role.

A brief drying of the overhead airmass will support a mix of mainly
MVFR conditions tonight with some periods of VFR conditions.
Scattered lake effect snow showers will likely continue and may
support a few areas of IFR vsbys and/or cigs east of the lakes.

Winds begin to shift to the southwest Tuesday morning, directing the
majority of the lake effect activity east-northeast of the lakes.
This will coincide with the increasing March sun angle, likely off-
putting the organizing lake effect activity and causing it to become
more cellular in nature. Confidence is low in exact timing and how
low vsbys ultimately will get though it appears likely that KBUF and
possibly KIAG will see a period of IFR conditions or lower in these
snow showers for a period near the end of the 18z TAF cycle.
Concurrently, SW wind gusts will likely approach 30kts at these
terminals with gusts of 20-25kts elsewhere.

Outlook...

Tuesday night 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 with increasing chances for snow showers.

Friday night through Saturday...MVFR with chances for snow showers.

&&

.MARINE...
Deep cyclonic flow across the lakes will maintain SCA conditions
across the nearshore waters through Tuesday.

Breezy WNW winds will freshen and back to the southwest Tuesday
morning. Sustained winds will likely approach 30kts across the open
waters of Lake Erie for a period on Tuesday.

Winds will shift westerly and briefly subside late Tuesday night,
before strengthening behind a cold front on Wednesday. Winds will
likely approach gale force on Lake Ontario Wednesday afternoon into
Wednesday night.

&&

.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.
         Gale Watch from Wednesday afternoon through late Wednesday
         night for LOZ042>045-062>065.
         Small Craft Advisory until 5 AM EDT Wednesday for
         LOZ043>045.

&&

$$

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


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