Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 160838
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
338 AM EST Sat Jan 16 2021

.SYNOPSIS...
A large storm system moving across the region will generate some
accumulating wet snow over the Eastern Lake Ontario region
today...then as the system exits across New England during the
second half of the weekend...lake enhanced snows will become more
widespread. Most areas will pick up an inch or so of accumulation by
Sunday night...while the Tug Hill region could see well over a foot
of snow. A more wintry pattern will then support frequent snow
showers and lower temperatures for the first half of the new work
week.

&&

.NEAR TERM /THROUGH SUNDAY/...
A large vertically stacked system will ease across our forecast area
today...while its associated sfc occlusion will continue its
eastward push into New England. In the process...the pcpn from its
low level forcing will taper off over the Finger Lakes region...but
upslope will combine with the residual forcing from the occlusion to
keep widespread wet snow falling over the Eastern Lake Ontario region.
Accumulations of 3 to 5 inches will be possible across the Tug with
lesser amounts over the remainder of the North Country. For the
western counties...today will feature a fair amount of cloud cover...
although some sun will be possible during the morning hours for
sites mainly west of the Genesee valley.

The large storm system will push across New England tonight.
Marginally cold air in its wake will support lake enhanced snow
showers east of both lakes. Nighttime snowfall is forecast to range
from an inch or two across the Southern Tier and Upper Genesee
Valley to 5 to 8 inches across the Tug Hill.

The slow moving upper level storm will then move across the Canadian
maritimes on Sunday...while thermal troughing extending back across
Lake Ontario will help to focus lake enhanced snows over the
southern half of the Tug and Oswego county. Snow showers will become
somewhat more widespread across the western counties during the
course of the day...with lake enhanced snows accumulating as much as
a few inches over the Southern Tier.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Sunday night, a boundary/wave draped from west to east along Lake
Ontario will still be in place Sunday night into early Monday. This
will provide the focus for snow to continue to fall over the
southern half of Lake Ontario, and extend inland into Oswego County
and to the Tug Hill Sunday evening, dropping south early Monday.
Lake enhancement along with the forcing from the wave will be the
driving factor with the band of snow. 850H temps on Sunday night
over and east of Lake Ontario will be in the -7C to -9C range.
Snowfall of around 1 to 2 inches will be possible along the south
shore and southeast of Lake Ontario and 1 to 3 inches (with some
isolated higher amounts) will be possible for portions of Central
and Southern Erie County into Western Wyoming County as winds off
Lake Erie look to bring the greatest lake enhanced snow. Other areas
across WNY can expect up to around an inch or two for Sunday night.
Temperatures Sunday night will be in the upper teens to low 20s for
the North COuntry, and in the mid 20s south of Lake Ontario.

This band will continue to slowly drop south as a mid and upper
level trough approaches the area. The trough, over the Ohio Valley
Sunday evening tracks east toward New England through the day on
Monday. As the trough approaches from the west, additional snow
showers will develop east of Lake Erie during the day on Monday due
to the forcing from the approaching trough, lake enhancement, and
upslope flow over the higher terrain south of Buffalo. Northwest
flow will continue to keep the potential for lake snow showers along
the south shore of Lake Ontario through most of the afternoon on
Monday until the trough passes to the east of the area. Snowfall for
Monday will be greatest over WNY, where a lake response with
upstream connection over Niagara County potentially causes 2 to 3
inches, and for the higher terrain east of Lake Erie where 1 to 2
inches of snow falls. Outside of these areas mentioned, generally a
half to one inch of snow can be expected, especially south of Lake
Ontario. Highs on Monday will be in the low to mid 20s for the North
Country, and in the mid 20s to near 30 for areas south of Lake
Ontario.

Monday night, lake enhancement east of Lake Erie will continue along
a boundary slowly moving south, but snow showers in general will be
possible for most locations south of Lake Ontario through the night.
Lows on Monday night will be in the upper single digits to low teens
for the North COuntry and in the low to mid 20s south of Lake
Ontario.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A clipper will track southeast out of the Upper Great Lakes Tuesday
afternoon into Tuesday night, providing the potential for a
widespread snowfall across the area. Behind the passing system, 850H
temps -10C or cooler. This will provide the opportunity for a
lake response off of both lakes for Wednesday, but synoptic
moisture as of right now looks minimal, so any lake response looks
weak with light snow.

Another area of low pressure will track from the Upper Great Lakes
to the St. Lawrence Valley from Thursday morning through Friday
afternoon, providing another chance for snow showers across the
area.

Temperatures will be in the low to mid 20s for the North Country and
in the upper 20s to mid 30s for areas south of Lake Ontario.
Wednesday will be chilly in the upper teens to low 20s for the North
Country and in the mid 20s to low 30s south of Lake Ontario.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
For the 06Z TAFS MVFR/IFR flight conditions are becoming widespread
as an occluded front pushes across the TAF airfields. Behind this
front, a dry slot will push its way into WNY, bringing a return to
VFR flight conditions early to the Southern Tier (KJHW) and by mid
morning for KBUF, KIAG and KROC. As this front slows, prolonged IFR
or lower flight conditions are expected for KART in both low ceiling
heights and visibility as snow develops.

For this afternoon most of WNY will remain VFR.

This evening as colder air returns across the Eastern Great Lakes
lake effect snow will develop. Initially these snows will be
multibanded across the southwestern portions of NYS, with brief
periods of IFR flight conditions (JHW) becoming more prolonged after
06Z. Through the night a single band plume of snow will orient east
of Lake Ontario and bring IFR and lower flight conditions through
the night, including for KART.

Outlook...

Sunday...MVFR/IFR, restrictions likely in snow showers east of both
lakes.
Monday through Wednesday...MVFR/IFR possible in scattered snow
showers east of both lakes.

&&

.MARINE...
While a weak pressure gradient will maintain gentle to moderate breezes
throughout the Lower Great Lakes this morning...winds will freshen
on the backside of a newly formed surface low in New England. The
strengthening winds will support small craft advisories that will
go into effect this afternoon and evening...pending your location
in the region.

Fresh to occasionally strong westerlies are then anticipated tonight
through Sunday...as the aforementioned sfc low will move from New
England to the Canadian maritimes. This will maintain the SCAs until
at least Sunday evening.

As the sfc pressure gradient weakens across the region Sunday night
and Monday...winds and waves will subside.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Storm Warning until 7 PM EST Sunday for NYZ006>008.
MARINE...Small Craft Advisory from 7 PM this evening to 10 PM EST
         Sunday for LEZ040-041.
         Small Craft Advisory from noon today to 1 AM EST
         Monday for LOZ043-044.
         Small Craft Advisory from noon today to 7 PM EST Sunday
         for LOZ042.
         Small Craft Advisory from 4 PM this afternoon to 10 PM EST
         Sunday for LOZ045.

&&

$$

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

NWS BUF Office Area Forecast Discussion