Forecast Discussion

Forecast Discussion for BUF NWS Office
000
FXUS61 KBUF 232334
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
634 PM EST Sat Jan 23 2021

.SYNOPSIS...
A cold northwest flow will continue to produce lake effect snow
showers southeast of Lake Erie and Lake Ontario through tonight,
with coverage and snowfall rates decreasing with time. High pressure
will build into the eastern Great lakes by Sunday morning, ending
the lake effect snow. Low pressure will pass just to the south of
the area Tuesday and Tuesday night, bringing a chance of widespread
accumulating snow to most of the region.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Cold northwest flow will continue to support lake effect snow
showers and narrow multiple bands southeast of Lakes Erie and
Ontario through tonight. The airmass is much drier than last night,
and inversion heights will continue to slowly lower with the
approach of high pressure. This will force the snowfall rates and
areal coverage to steadily decrease through tonight.

Off Lake Ontario...

Multiple streamers are found along the entire south shore of the
lake from Niagara County to Oswego County, and extending inland into
the Finger Lakes region. The best banding is stretching from the
Rochester area into portions of the Finger Lakes where the upstream
connection to Georgian Bay is still tied in. The coverage of snow
will continue to slowly decrease through the evening. The Canadian
GEM suggests a convergence band will likely continue through at
least the first half of tonight along the Monroe County shoreline
then extending inland from near Irondequoit Bay into Wayne County.
This will eventually evolve into a tea kettle band and retract north
and west over the lake Sunday morning as synoptic scale flow weakens
and land breeze circulations become dominant.

Expect additional accumulations to be limited to 1-2 inches in most
locations to the southeast of Lake Ontario through tonight. The
convergence band may produce a fluffy 2-4 inches in a few spots from
near Irondequoit Bay into portions of Wayne County.

Off Lake Erie...

Widespread light snow showers and a few narrow bands of somewhat
better snow will continue through this evening, mainly across the
higher terrain of the western Southern Tier. This is from a
combination of Lake Erie and Lake Huron banding. The upstream
connection to Lake Huron will continue through this evening then
break down overnight as high pressure reaches far southern Ontario.
Any remaining snow showers will end by daybreak Sunday.

Expect additional accumulations to generally be 1-2 inches across
the higher terrain of the western Southern Tier, with a few local 3
inch reports across the Chautauqua Ridge.

Lows will drop into the teens in most locations tonight, with lake
effect clouds preventing radiational cooling. The one exception will
be the North Country, where skies will clear with no off-lake flow.
This will allow lows to drop below zero. There will be a very light
breeze producing wind chills of around -15F, but most areas are
expected to remain just above wind chill advisory criteria.

Once the lake effect snow ends Sunday morning, high pressure will
bring a return to mainly dry weather. A weakening mid level
shortwave will reach the eastern Great Lakes during the afternoon
and evening. This feature will produce some light snow on Sunday
upstream across lower Michigan, but is forecast by all model
guidance to weaken and dissipate prior to reaching Western NY,
allowing dry weather to continue into Sunday night with a period of
mid level clouds crossing the region.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Surface high pressure wedged firmly across eastern NY and western
New England will keep our area dry on Monday. Somewhat warmer air
aloft will make some headway into western NY during the day, however
will have a more difficult time making it any further east/northeast
than the Finger Lakes region due to aforementioned ridge holding
strong across areas east of Lake Ontario. That said, it will be a
bit warmer of a day overall with low to mid 20s east of Lake Ontario
and upper 20s to low 30s elsewhere.

Our attention then turns to the next storm to potentially impact our
region Monday night/Tuesday, possibly lingering into Tuesday night.
23/12Z Canadian has come back into much better agreement with a more
northerly track as continues to be advertised by the 23/12Z
ECMWF/GFS. Given the current scenario, the storm will track from the
mid Mississippi Valley/lower Ohio Valley Monday night, then
northeast through Ohio into northern Pennsylvania by Tuesday night.
One of the main forecast challenges continues to be the significant
weakening of this storm system as it starts to impact our region.
Moisture looks fairly limited and forcing is not that impressive.
Putting it all together, moisture in the form of light snow should
make into southwestern NYS by the second half of Monday night, then
spread across areas south of Lake Ontario on Tuesday, possibly
lingering across southeastern portions of our forecast area Tuesday
night.

Chances for the better accumulating snows will remain toward the
NY/PA line. Would still not rule out low end advisory amounts across
the higher terrain well south of Buffalo. If the system tracks any
further north, will have to continue to monitor trends for any p-
type issues across southern areas as warmer air could make a push a
bit further north if this were to occur. As of now, still appears
any rain/snow mix would remain just south of the NY/PA line.
Otherwise, daytime highs on Tuesday will be mainly the 20s, with
some very low 30s possible across far western NY. As for lows,
expect single digits and teens east of Lake Ontario, with generally
low to mid 20s elsewhere.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Expect brief upper ridging across the area for Wednesday, with drier
weather overall, but cannot rule out a few lingering scattered snow
showers. Weak upper level trough and associated surface cold front
crosses the region Wednesday night and Thursday bringing the next
chance of snow showers to our area. Strong high pressure will then
build over the eastern third of the CONUS, bringing a mainly dry
finish to the work week and start of next weekend. However,
this area of high pressure will slide off the East Coast by
later Saturday. This will clear the way for a warm front to
approach the area, possibly bringing a return of some
precipitation by later Saturday.

Otherwise, daytime highs will remain below normal through the end of
the work week with temperatures ranging mainly through the 20s, with
some upper teens east of Lake Ontario. Warmer air will make a push
into the area Saturday, pushing daytime highs to near or possibly a
bit above average.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Cold northwest flow will continue to support multiple bands of lake
effect snow showers southeast of Lakes Erie and Ontario through
tonight, with coverage and intensity gradually diminishing. The
bands of snow showers will produce periods of IFR VSBY and MVFR CIGS
through tonight southeast of the lakes. This may impact KJHW and
KROC at times through this evening. KBUF, KIAG, and KART will miss
most of the snow showers in this flow regime.

The lake effect snow showers will come to an end southeast of the
lakes Sunday morning, with a return to mainly VFR as mid level
clouds increase from west to east ahead of a weakening mid level
trough.

Outlook...

Monday...Mainly VFR.
Tuesday...Snow developing with IFR, especially south of Lake
Ontario.
Wednesday...Scattered snow showers with local IFR and MVFR CIGS
in the morning, improving to VFR.
Thursday...A chance of snow showers south of Lake Ontario with
local MVFR/IFR possible.

&&

.MARINE...
Moderate northwesterlies will continue to produce Small Craft
Advisory conditions on Lake Ontario through Sunday morning. High
pressure will then build into the eastern Great Lakes Sunday,
allowing winds and waves to subside. Light winds will last through
Monday.

Low pressure will then move from the Ohio Valley Monday night
eastward across Pennsylvania Tuesday and Tuesday night, with high
pressure remaining to the north of the Great Lakes. This will allow
for a period of stronger ENE winds on Lakes Erie and Ontario with
another round of Small Craft Advisory conditions possible.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 10 AM EST Sunday for LOZ043-044.
         Small Craft Advisory until 4 AM EST Sunday for LOZ042.
         Small Craft Advisory until 7 AM EST Sunday for LOZ045.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock/RSH
SHORT TERM...JM
LONG TERM...JM
AVIATION...Hitchcock/RSH
MARINE...Hitchcock

NWS BUF Office Area Forecast Discussion