718
FXUS61 KBUF 232218
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
518 PM EST Sat Nov 23 2024

.SYNOPSIS...
Potential for rain and some nocturnal elevation dependent snow will
continue through early Sunday. After a brief period of dry weather
Sunday night, widespread chances for rain enter region Monday
evening. Additionally, with the passage of this next system, a
colder airmass and chances for precipitation downwind of lakes will
continue through Wednesday.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Low pressure off the northern coast of Maine this evening, will not
only continue to gradually track northeast into the Canadian
maritimes tonight, but become vertically stacked helping to fill in
the low. Currently across the area, the remnants of the deformation
band that was across Western New York this afternoon has pushed into
the eastern portions of the area, supporting an uptick of showers.

For the rest of the evening, as the weakening deformation band pulls
further east, chances for scattered showers with some lake
enhancement will spread from west to east.

Then tonight into Sunday, a mid-level shortwave will drop southeast
from the Ontario province to the eastern Great Lakes. This will
bring a reinforcing shot of colder air (850 mb temperatures around
-5C). However, there will be a lack of moisture to tap into and
therefore not expecting a robust lake response southeast of both
Lake Erie and Ontario. This being said, have brought down the
chances for precipitation from the earlier forecast. If showers do
develop expect a mix of rain and snow, as well as some drizzle. The
best placement of lake enhancement will lie across the Southern Tier
where the skinny ribbon of moisture will be located. While the
response off of Lake Ontario will not be as impressive, the likely
hood of lake enhancement will depend on whether the activity can tap
in on a lake-to-lake connection with the Georgian Bay. Snow
accumulations look to be minor with the best chances across the Tug
Hill.

Sunday, lingering lake effect will gradually deplete as mid-level
ridging, associated surface high pressure and subsidence enters the
region. Expect activity to end from west to east. Dry weather will
then last through Sunday night as high pressure remains overhead.
While dry, lingering lake clouds Sunday night will support lows
across the areas south of Lake Ontario to drop into the 30s, whereas
clear skies across the North Country combined with calm winds will
support ample radiational cooling with lows tumbling into the low to
mid 20s.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
High pressure ridged across New York State at the start of Monday
will slide east into New England through the course of the day...
while the next upper trough digs across the Upper Great Lakes...and
its corresponding surface low tracks from near Chicago across Lower
Michigan. After a largely dry morning...this next system will bring
increasing chances for rain showers to areas from the Finger Lakes
westward during the afternoon. Otherwise milder air advecting across
our region will result in a milder day...particularly across areas
south of Lake Ontario where highs should reach the upper 40s and
lower 50s. Meanwhile...areas east of Lake Ontario should see
readings top out in the lower to mid 40s.

Monday night and Tuesday the upper level trough will take on a
substantial negative tilt as it ejects northeastward across the
Lower Great Lakes and Northeast...with its attendant surface low
correspondingly deepening as it tracks over/just to the north of our
area. Expect fairly widespread showers across our area Monday night
into early Tuesday associated with this system`s warm and trailing
cold fronts...for which categorical PoPs remain in the forecast.
Following the cold frontal passage...a westerly upslope flow of
colder air should then support some mixed rain and wet snow showers
across the higher terrain east of both lakes during the balance of
Tuesday...with a few more leftover rain showers possible elsewhere.
Depending upon the exact track of the low...there could also be a
period of windy conditions in the wake of the cold front...with a
low track a bit to our north most favorable for this...while a low
track directly overhead would eliminate this potential.

Tuesday night and Wednesday a general westerly to west-northwesterly
flow of colder air will continue across our region...with consensus
850 mb temperatures bottoming out somewhere in the -6C to -7C range
Tuesday night. This will keep at some lake effect snow and rain
showers going east and east-southeast of both lakes...though dry air
advection should cause the activity to gradually weaken from west to
east later Tuesday night and Wednesday. At this point expecting some
minor accumulations appear likely across the higher terrain...
particularly east of Lake Ontario where available moisture will be
deeper/persist longer. Otherwise just expect a few more scattered
rain and snow showers and colder temperatures...with lows Tuesday
night in the upper 20s/lower 30s...and highs Wednesday ranging from
the mid/upper 30s across the higher terrain to the lower 40s across
the lake plains.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Moving on into the longer term portion of the forecast...the 12z/23
guidance suite has trended further north again with the track of a
southern stream system that at this time yesterday looked to
primarily bypass us to our south. The three main operational
guidance packages are actually all now in decent agreement on this
system bringing us another shot of rain/snow for later Wednesday
night and Thanksgiving...and with this in mind have bumped PoPs up
into the mid-high chance range for this time period...though
for now have refrained from going higher given the recent
inconsistencies in the handling of this system.

By Friday morning the center of this system should be off to our
east...with lingering wraparound/lake-enhanced precipitation on its
backside then looking to change over to snow and become increasingly
more lake-driven over time as deep cyclonic flow advects
progressively colder air (consensus 850 mb temps falling to around
-10C) across our region Friday through Saturday. Given a general
west-northwesterly to westerly flow...this should set the stage for
some accumulating lake snows east-southeast and east of both
lakes...with more scattered snow showers found elsewhere. Meanwhile
temperatures will fall to a bit below normal for the end of
November...with readings both Friday and Saturday struggling to get
above the upper 20s (higher terrain) to mid 30s (valleys and lake
plains).

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
A mid-level trough will slide north of the region tonight, causing
cold air to deepen over the lakes, supporting a limited lake
response southeast of both lakes while cigs range from low VFR to
MVFR. Moisture within this trough will be lacking however, so not
expecting activity to be heavy though MVFR vsbys will again be
possible in lake showers. The most persistent activity will again be
southeast of Lake Erie, but also southeast of Lake Ontario between
KSDC and KFZY.

Outlook...

Sunday...VFR/MVFR with a chance of a rain or snow shower.

Monday...VFR/MVFR with a chance of rain during the afternoon and
evening.

Tuesday...MVFR with rain and snow showers likely.

Wednesday and Thursday...VFR/MVFR with a chance of rain or snow
showers.

&&

.MARINE...
A large low pressure system off the northern coast of Main this
evening will continue to move northeast to the Canadian Maritimes
tonight, before slowly weakening and drifting east into the Atlantic
Monday. As the system moves and tightens the pressure gradient over
the lakes, winds have strengthened to the WNW. Winds and waves are
expected to remain elevated through Sunday.

This being said, SCAs for Lake Erie and Lake Ontario continue.
Occasional gale force gusts are possible this evening and overnight
tonight, mainly over the southeastern portion of Lake Ontario.

A ridge of high pressure will then bring subsiding winds and waves
across the lakes Sunday night through early Monday night.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 4 PM EST Sunday for LEZ040-041.
         Small Craft Advisory until 7 PM EST Sunday for
         LOZ042>045.

&&

$$

SYNOPSIS...EAJ
NEAR TERM...EAJ
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...EAJ
MARINE...EAJ/PP