Henrietta, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

433
FXUS61 KBUF 220239
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
939 PM EST Sat Dec 21 2024

.SYNOPSIS...
High pressure will gradually drift east and southeast across our
region through Sunday. Residual lake snows will gradually taper off
through tonight, but it will remain very cold through Sunday where
mercury readings will be found in the single digits east of Lake
Ontario...while the remainder of western New York will not escape
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 SUNDAY/...
Currently, lingering on and off lake snow showers can be found for
most areas south of Lake Ontario, with the best chance for snow
showers southeast of both lakes. Current temperatures range from a
few degrees below zero, to the mid teens, with the coolest spots
found under clear skies, and the "warmer" locations found under a
blanket of lake clouds.

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 be found
southeast of Lake Ontario...especially where Winter Weather
headlines remain in place (Wayne, N. Cayuga, and Ontario County).

Surface ridging found over southeastern Ontario Canada this evening
will continue to ridge east and southeast over the Lower Lakes
tonight. Some measure of lake clouds will reside across the western
counties and light lake effect snow will continue between Rochester
and western Oswego county. There, we may see an additional fluffy 1
to 3 inches of snow accumulation overnight. Otherwise...with a
frigid airmass (-18C @ 850 mb) in place....mercury readings will
quickly fall off where we see some measure of clearing take place.
Lows tonight will range from 10F to below zero across the North
Country. Apparent temperatures over the Tug Hill and in the western
foothills of the `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 will finally kill off the 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 between 10 and 15 in the North country.

&&

.SHORT TERM /SUNDAY NIGHT 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 /03Z SUNDAY THROUGH THURSDAY/...
A very cold airmass will continue to generate lake snows southeast
of the lakes, especially southeast of Lake Ontario through most of
the overnight. This will bring the potential for IFR-MVFR vsbys/cigs
to any terminals impacted by the lake snows. For terminals (KART)
outside of the lakes snows...expect mainly VFR cigs.

Mainly MVFR cigs are then forecast for the region tonight outside of
the lake snows, which will mainly focus southeast of Lake Ontario.

Outlook...
Sunday...Mainly VFR but with areas of MVFR conditions in light lake
snows between KROC and KSYR.
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 tonight. 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 Sunday for NYZ004-005-
     014.
MARINE...Small Craft Advisory until 4 AM EST Sunday for LOZ042>045.

&&

$$

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