Irondequoit, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

511
FXUS61 KBUF 220712
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
212 AM EST Sun Dec 22 2024

.SYNOPSIS...
High pressure will gradually drift east and southeast across our
region through Sunday. Residual lake snows will gradually taper off
through Sunday morning, but it will remain very cold through Sunday
with temperatures in the single digits east of Lake Ontario, while
the remainder of western New York will not eclipsing the teens.
Looking further ahead, a weak storm system Monday night and Tuesday
should be able to generate enough nuisance snow to support a white
Christmas for most areas.

&&

.NEAR TERM /THROUGH TODAY/...
Lingering light lake effect snow showers continue for most areas
south of both lakes. Very cold across the North Country already
where less cloud cover/fresh snowpack has allowed readings to
fall below zero, in some cases well below zero. Single digits
to very low teens elsewhere.

The axis of a sharp mid-level trough is crossing the eastern Great
Lakes and will gradually exit off to our east through Sunday. This
trough has delivered with it an Arctic airmass (-36C @ 500 mb),
which is the coldest airmass so far this winter season. With such a
frigid airmass filtering in across the Lower Lakes, and water temps
still +5C/+6C, we will continue to see some light accumulating lake
snows. That said, lake snows will be muted to a degree given the
shorter fetch and drier air working into the region. However, any
upstream connections will `likely` give some added boost. Greatest
chances to see additional accumulations will continue to be found
southeast of Lake Ontario, where a Winter Weather Advisory remains
in place (Wayne, N. Cayuga, and Ontario County). Far western Oswego
County will continue to see some lake snow showers as well.

Surface ridging will build into southeastern Ontario Canada by early
Sunday morning, keeping a general northerly flow in place. Thus,
lake induced clouds will reside across the western counties and more
persistent light lake effect snow will continue between Rochester
and western Oswego county through the remainder of the overnight.
There, may see an additional localized fluffy 1 to 2 inches of snow
accumulation by early Sunday morning. Otherwise, with a frigid
airmass (-19 to -22C @ 850 mb) in place, mercury readings will range
from 10F to below zero across the North Country to the single digits
elsewhere by Sunday morning. Apparent temperatures over the Tug Hill
and western Dacks will be as low as -15F.

The large area of high pressure will drift directly across our
forecast area on Sunday. This will guarantee dry weather for the
majority of the region, although residual nuisance lake snow showers
will be found southeast of Lake Ontario into the midday hours when
weak warm advection, drier air/subsidence and a wind shift will
finally shut down and remaining lake response. Our persistent cloud
cover will start to `open up` mainly outside of the aforementioned
lake snow shower area. The main thing to know about Sunday is that
it will be coldest day so far this season with afternoon
temperatures ranging from the teens over the western counties to
only single digits in the North country.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
Surface high pressure will start Sunday night over our region, with
clear skies again allowing temperatures to quickly fall through the
evening...on their way to the single digits across WNY, and below
zero east of Lake Ontario. As this surface high slips eastward,
southerly flow and increasing mid and high level clouds will allow
for temperatures to increase slightly through the later half of the
night.

A couple of mid level shortwaves will drive a surface low across the
eastern Great Lakes Monday night. Deepening moisture coupled with
lift ahead of the shortwaves will bring a period of synoptic snows
across the region Monday night, with snows lingering into Tuesday as
a secondary surface trough drops southward across Lake Ontario. Low
snow ratios at first with the lower atmosphere cooling below
freezing, and could see at onset a rain snow mix near the Lake Erie
shoreline and western Lake ONtario shoreline before the atmosphere
sufficiently cools for an all snow event. These upslope snow showers
south of Lake Ontario Tuesday afternoon will taper down to flurries
through the evening hours. Overall snow will range one to three
inches, but east of Lake Ontario where surface convergence near the
center of the surface low lingers longer greater snow amounts of 3
to 5 inches are possible.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Building mid and upper level ridging will keep much of this period
quiet, with a warming trend as deeper southerly flow develops.

A weakening shortwave trough, with moisture thinning as it builds
into a dry airmass Christmas night may bring light snow showers to
Western New York. Not looking for much, if any accumulation as
moisture thins.

This ridge will maintain Thursday and Friday dry with temperatures
increasing above the freezing mark for parts of the region Thursday,
and then most of the region Friday.

An amplifying flow will bring the next system of note into the
western Great Lakes Saturday, possibly with rain spreading eastward
across our region as soon as Saturday. This amplifying, southerly
flow will maintain mild temperatures Friday night into Saturday.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
A cold northerly flow will continue to produce lake clouds and light
lake effect snow showers south of the lakes through the remainder of
the overnight into at least Sunday morning. Expect mainly MVFR CIGS
and VFR VSBY in very light snow showers for terminals south of both
lakes through Sunday morning, although some brief periods of
localized MVFR/IFR VSBYs will be possible in areas of more
persistent snow showers. Shallow low level moisture trapped under a
stout low level inversion has advected south into KART from the
Saint Lawrence Valley, thus high-end MVFR CIGS will likely continue
into at least a portion of Sunday morning.

Light nuisance lake effect snow showers will finally taper off as
they retract over Lake Ontario through the afternoon with high
pressure building in, however MVFR CIGS may linger into at least a
portion of the afternoon south of the lakes, with VFR east of Lake
Ontario.

Widespread VFR flight conditions are then expected later Sunday and
Sunday night with high pressure over the area.

Outlook...

Monday...VFR.

Tuesday...Restrictions possible with rain/snow showers likely.

WEDNESDAY and THURSDAY...VFR.

&&

.MARINE...
Moderate northerlies will continue to produce some modest chop on
Lake Erie but below SCA levels overnight. Widespread Small Craft
Advisories will remain in place on Lake Ontario through most of the
overnight.

A large Canadian sourced high pressure will approach from the upper
Great Lakes and move over the lakes through Sunday. This will allow
winds to subside everywhere across the lakes. Light northerlies and
negligible waves are expected for Sunday as the area of high
pressure will be directly over the region.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 AM EST early this morning for
     NYZ004-005-014.
MARINE...Small Craft Advisory until 4 AM EST early this morning for
         LOZ042>045.

&&

$$

SYNOPSIS...AR/JM
NEAR TERM...AR/JM/RSH
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...JM
MARINE...AR/RSH