National Weather Service Raw Text Product

370 
FXUS61 KBUF 202018
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
318 PM EST Sun Nov 20 2022

.SYNOPSIS...
Heavy lake effect snow will impact southeast of Lake Ontario, 
centered on Oswego county through this evening. Moderate to locally 
heavy lake effect snow bands will impact the Southern Tier into this 
evening. Additionally gusty winds this afternoon and again on Monday 
will create blowing and drifting of the recently fallen snow.

&&

.NEAR TERM /THROUGH MONDAY/...
Two plumes of lake effect snow continue to the east of the Lakes. 
Outside these plumes of snow, breezy conditions with west gusts up 
to 45 mph have created blowing snow with reduced visibilities, as 
well as drifting of snow. Interesting that wind gusts briefly 
reached 45-48 mph over portions of the Niagara Frontier/Genesee 
valley where it is sunny and mixing has been maximized. These 
stronger winds are beginning to diminish recently though. Cold 
persists with single digit wind chills into tonight all areas. 

Off Lake Erie...

A westerly flow has focused the snow showers across the Southern 
Tier. Mainly moderate intensity, though have seen a few heavier snow 
showers as well. Shallower lake equilibrium level and drier air and 
connection lessening off upstream lakes will continue to diminish 
the snow into tonight. Remnants of this snow will come back north 
overnight across Buffalo in a much weakened state. Total snow 
accumulations through tonight will be a few inches of fluffy snow in 
the Southern Tier to an inch or two otherwise across far WNY, 
including the Buffalo Metro.

Off Lake Ontario...

Much more well developed, but still wavering band of lake effect 
continues to impact the corridor from Oswego into southern Lewis 
county early this afternoon helped by wnw flow bringing in upstream 
connections to central Great Lakes. Radar trends and consensus of 
high-res guidance, including HRRR and Canadian High res do point to 
a more notable shift southward of this band into at least early
evening, so this will put the band into far northeast Wayne, 
far northern Cayuga and much of Oswego county. Snowfall rates of
2-3" per hour likely along with some lightning. No changes to 
the going headlines. This shift will have to happen for snow to 
come into Wayne county, but again, it looks to be occurring at 
present. Oswego county should see storm totals since late last 
night of 2-3 feet in some areas. 

Later tonight, similar to the Lake Erie band, expect the band to 
weaken and shift back to the north across northern Oswego, much of 
Jefferson and adjacent Lewis county. A lot of the weakening will 
occur due to loss in upstream connections, but there is a hint that 
the plume of moisture from Lake Erie band will try to briefly 
connect with the eastern Lake Ontario band. If that were to happen r 
rates could push toward 1" per hour into Watertown late tonight with 
up to a few inches of accumulation tonight.   

By Monday morning the weakening bands of snow...with their last 
gasps of light snow showers at Buffalo/Niagara Falls and Watertown 
will lift into Canada by late morning, losing any upstream lake 
connection, and finally ending. This lake effect snow event starting 
Wednesday evening for some locations has been a very long duration 
event lasting over 100 hours.

Later Monday a cold front will advance across southern Canada and 
our region. Residual lake moisture collecting ahead of the front may 
bring a few rain or snow showers back into our region. Of bigger 
concern a tightening pressure gradient ahead of the upstream trough 
and departing surface high will bring wind gusts about 5 to 10 mph 
stronger than Sunday. While this could continue the blowing snow, 
the extra day of compaction along with surface temperatures rising 
above freezing in many locations will reduce the blowing snow 
threat. Regardless, winds possibly gusting towards advisory levels 
will occur northeast of the Lakes and possibly even toward ROC on 
the Niagara Frontier.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
There may be some lingering lake effect snow showers Monday night as 
a shortwave passes by to our north. It does look marginally cold 
enough for snow, with -6C at 850mb ahead of the shortwave. Any 
accumulations will be minor especially considering recent snowfall. 
Expect less than an inch east of Lake Erie, and 1-3 inches on the 
Tug Hill. On Tuesday night despite a more zonal flow developing, 
weak southwest low-level flow sets up and it again is just 
marginally cold for a lake response (-6c at H85) though inversions 
are only 3-5kft. Just a small chance we could see some snow showers 
northeast of Lake Ontario. This would then shift toward southeast 
Lake Ontario on into Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A shortwave trough overhead Wednesday morning will track east of
the area by Wednesday afternoon. Westerly flow and marginally 
cold enough temperatures for lake effect may result in some rain
and snow showers east of Lake Ontario through the afternoon. 
Elsewhere, dry conditions expected. Highs will reach the low 
40s. 

The synoptic pattern will become amplified the latter half of the 
week as trough deepens across the Mid-West region and an upper level 
ridge builds across the Northeast. Surface low pressure will be 
deepening east of the trough however timing and location is yet to 
be determined. Warm air and moisture advection is likely across the 
eastern Great Lakes region beginning Thursday night and rain and 
snow showers are likely during this time period. It is fairly 
certain that moisture and cold air will wrap around this system 
through the weekend with lake effect snow showers possible.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
Bands of lake effect snow with visibilities dropping to VLIFR to 
LIFR continue to the east of the Lakes. Off Lake Erie the band has 
settled south of the Buffalo and Rochester airports and will impact 
KJHW this afternoon with IFR/LIFR visibility. Otherwise, even 
outside of this band, gusty winds to 35 knots will result in blowing 
snow at times at BUF and IAG.  

Off Lake Ontario into this evening the primary snow band will 
persist southeast of Lake Ontario between ROC and ART. Mainly VFR at 
ART, though there will be occasional BLSN and reduced visibility. 

Tonight the lake effect snow will begin to drift northward again, in 
a much weaker state. A few snow showers, with brief reduction to IFR 
is possible for KBUF and KART by the end of tonight. 

Outlook...

Monday....MVFR/VFR with a chance of rain and snow showers. Very 
Windy with gusts 40 knots or greater possible. 
Tuesday through Thursday...Mainly VFR.
Friday...Chance of rain and snow showers. MVFR/IFR possible.

&&

.MARINE...
Gale force winds this afternoon will diminish some tonight, then 
back to southwest on Monday while increasing to 35-40 knots on both 
Lakes. In coordination with NWS Cleveland and Canada we have ran 
with one gale warning through Monday, even though there will likely 
be a 12+ hr window of sub-gale force winds tonight on the Lakes.  

Small craft advisories will be in place for the Niagara River as 
well as the Saint Lawrence River. Winds are expected to be stronger 
Monday on the Saint Lawrence River where a southwesterly flow down 
the river valley could reach 25 knots sustained. 

High pressure will push towards the region Monday night and 
Tuesday, relaxing the pressure gradient and allowing for winds and 
waves to decrease.

&&

.TIDES/COASTAL FLOODING...
Strong winds late today will cause levels on Lake Erie to rise 
some. Water levels will likely approach 6 feet above low water 
datum at the Buffalo NOS station. Levels higher than this can 
cause minor splash over in a few spots along the Lake Erie 
shoreline.

&&

.CLIMATE...
Buffalo airport received 21.5 inches of snowfall Saturday, 
breaking the daily record and bringing our monthly total 36.9 
inches. Saturday, November 19th was the 2nd snowiest calendar
day for the month of November in Buffalo's history...trailing
only the November 20, 2000 date which had 24.9 inches of snow. 
This snow also makes November 2022 the 2nd snowiest on record 
(the snowiest is back in 2000 when there was 45.6 inches of 
snow).

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 7 PM EST this evening for NYZ001-
     002-007-010>012-085.
     Winter Weather Advisory until 1 AM EST Monday for NYZ004.
     Lake Effect Snow Warning until 1 AM EST Monday for NYZ005.
     Lake Effect Snow Warning until 4 AM EST Monday for NYZ006-008.
     Lake Effect Snow Warning until 10 PM EST this evening for 
     NYZ019-020.
     Winter Weather Advisory until 10 PM EST this evening for 
     NYZ021.
MARINE...Small Craft Advisory until 7 PM EST Monday for LEZ020.
         Gale Warning until 10 PM EST Monday for LEZ040-041.
         Small Craft Advisory until 7 PM EST Monday for LOZ030.
         Gale Warning until 1 AM EST Tuesday for LOZ042>045-062>065.
         Small Craft Advisory until 10 PM EST Monday for 
         SLZ022-024.

&&

$$

SYNOPSIS...JLA/Thomas
NEAR TERM...JLA/Thomas
SHORT TERM...JLA
LONG TERM...HSK
AVIATION...JLA
MARINE...JLA/Thomas
TIDES/COASTAL FLOODING...Apffel/TMA
CLIMATE...Thomas