Area Forecast Discussion
Issued by NWS Buffalo, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBUF 291958
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
258 PM EST Tue Nov 29 2022

.SYNOPSIS...
Low pressure will pass well northwest of our region Wednesday,
bringing another period of rain. A strong cold front will sweep
across the eastern Great Lakes Wednesday afternoon, with very gusty
winds as colder air pours back into the region. The cold air will
set the stage for a brief period of accumulating lake effect snow
east of Lake Ontario and Lake Erie Wednesday night through Thursday.

&&

.NEAR TERM /THROUGH THURSDAY/...
High pressure drifting east off the New England coast will maintain
dry weather through the first half of tonight. There will be some
breaks in the lingering stratus cloud cover, but this will be
replaced by approaching mid/high clouds. Late afternoon temperatures
will mainly be in the 40s. Low temperatures tonight will be reached
during the evening hours, with lows ranging from the lower 30s east
of Lake Ontario to the lower 40s across the Western NY lake plains
where southerly downsloping winds will keep things warmer.

An amplifying upper level pattern will result in an active weather
pattern late tonight through Thursday. A strong surface low will
move from just north of Lake Superior to the eastern shores of
Hudson Bay Wednesday and Wednesday night. A trailing cold front will
arrive in Western NY by late morning or midday in Western NY, then
reach the eastern Lake Ontario region in the afternoon. Cold air
will pour back into the eastern Great Lakes briefly behind this cold
front, setting the stage for a brief lake effect snow event east of
the lakes Wednesday night and Thursday. This system will have
multiple impacts, outlined below.

Rainfall...

A period of rain will move from west to east across the area late
tonight and Wednesday. Rain will focus along and ahead of the cold
front, supported by strong large scale ascent as DPVA and height
falls overspread the area ahead of a deep trough swinging through
the Great Lakes. Across Western NY the steady rain should end by
early afternoon, transitioning to scattered rain and snow showers
following the frontal passage.

Rainfall across Western NY are forecast to be in the 0.50"-0.75"
range. East of Lake Ontario, a developing frontal wave will likely
enhance rainfall with amounts of 0.75"-1.0" in general, and 1.0"-
1.5" for the southern Tug Hill with strong southerly upslope flow
ahead of the cold front.

Wind...

Southerly winds will increase tonight as a strong 45-50 knot low
level jet moves into the eastern Great Lakes. For most areas these
will not readily mix to the surface, however to the lee of the
Chautauqua Ridge and the Tug Hill Plateau these will mix due to
downsloping with gusts to 55 mph. This will include the Lake Erie
shoreline and I-90 south of Hamburg, and the Black River Valley.
Winds will also be gusty in the western Finger Lakes and Southern
Tier with local channeling of the south winds resulting in gusts of
45-50 mph.

The second phase of this wind event will be post-frontal winds on
the lake plains. Forecast wind profiles in the cold air behind the
front are not overly impressive, but strong cold advection and
subsidence behind the front should allow for the majority of the 45
knots aloft to mix down to the surface following the cold frontal
passage. The strongest gusts in Western NY downwind of Lake Erie
will likely be from midday into the evening Wednesday with gusts to
around 50 mph expected. Farther east, 50 mph wind gusts will start
Wednesday afternoon and may go through Thursday along the Lake
Ontario shore from near Rochester eastward to the east end of the
lake.

Based on this, have expanded the Wind Advisory to include the entire
forecast area, although the initial downslope winds will be more
localized. Winds will diminish from west to east on Thursday as the
pressure gradient relaxes.

Lake Effect...

Cold air will pour back into the eastern Great Lakes behind the cold
front, with 850MB temps bottoming out around -11C or so Wednesday
night and Thursday morning. Lake induced equilibrium levels will
briefly rise to 12-14K feet Wednesday evening over Lake Ontario, and
around 10K feet over Lake Erie before steadily lowering Thursday.
The best synoptic scale forcing and moisture will be found over and
east of Lake Ontario, which will benefit from moisture from the
upper Great Lakes. A somewhat less favorable setup over and east of
Lake Erie with more shallow synoptic scale moisture.

Off Lake Ontario...

Expect a band of lake effect rain/snow to develop quickly on the
heels of the departing synoptic scale rain late Wednesday afternoon
and early evening across Jefferson and northern Lewis counties. The
rain/snow mix will quickly change to all snow by late evening as
colder air arrives. The lake effect band will drift slowly south
across the Tug Hill Wednesday night through Thursday, eventually
becoming centered on the far southern end of the Tug Hill and
portions of Oswego County on Thursday. The band should reach peak
intensity Wednesday night and early Thursday morning across the
Central Tug Hill before weakening late morning into the afternoon.

The greatest snowfall amounts will be focused across the higher
terrain of the Tug Hill where surface temperatures will be colder,
and where upslope flow enhances snowfall rates. Expect totals of 8-
16" in the most persistent bands there. Surrounding lower elevations
will see considerably less, on the order of 4-8", even less than
that right on the lakeshore. A Lake Effect Snow Warning remains
in place for east of Lake Ontario.

Off Lake Erie...

A band of lake effect rain and wet snow will develop by late
afternoon east of the lake, changing to all snow by sunset across
higher terrain and by early evening for lower elevations. The
initial band for the first few hours may impact the Buffalo
Southtowns before drifting further south in the evening. Wednesday
night through Thursday morning the most organized bands of lake
effect snow will follow a slow southward progression, starting
mainly in southern Erie and Wyoming counties in the evening before
moving south to Chautauqua and Cattaraugus counties overnight
through Thursday morning. The Lake Erie activity should reach peak
intensity Wednesday evening through the early overnight before
weakening late Wednesday night and Thursday morning.

The greatest snowfall off Lake Erie will focus across the higher
terrain of the Boston Hills, western Wyoming County, and Chautauqua
Ridge where 4-7" is expected. Amounts will be lower along the Lake
Erie shore, Buffalo Southtowns, and Allegany County where 2-4" is
expected. The strong winds will support snows extending well inland
from the lake, with 1-3" locally extending into the western Finger
Lakes as well.

Blowing Snow...

The gusty winds will produce areas of blowing and drifting snow
Wednesday night through Thursday in lake effect areas. Visibility
will be significantly impacted at times with gusts to over 40 mph.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Thursday night the axis of low-level ridging will slide east across
New York State. The accompanying drying...lowering inversion
heights...and backing/increasingly sheared low level flow will all
help to bring about the demise of any lingering lake effect snow
showers east of Lake Ontario...while providing fair dry weather to
the rest of the area. Lows will range from the upper teens across
interior portions of the Southern Tier/North Country to the lower to
mid 20s elsewhere.

On Friday a flat mid/upper level shortwave trough will push across
the Rockies and western Plains...while spurring leeside surface
cyclogenesis across the Plains States. Downstream of this next
system...corresponding broad/flat upper level ridging will build
across the Great Lakes...while the aforementioned surface ridge
slides off the east coast. The latter will provide our region with a
dry day...with the deepening southerly flow between the departing
surface high and Plains low also helping to bring about a quick
return to above normal temperatures. Highs will climb back into the
mid to upper 40s in many areas...with readings likely to reach or
even break 50 across the lower elevations of far WNY...where
increasing downslope flow will provide an additional boost.

Friday night through Saturday night the aforementioned trough will
slide eastward across the northern third of the CONUS...with its
attendant surface low deepening and tracking northeastward across
the Great Lakes and southeastern Canada. The exact track of this
system is still uncertain with the 12z guidance suite suggesting
possibilities ranging from Lake Superior to northern Quebec (GFS) to
Georgian Bay and Southern Ontario/Quebec (ECMWF)...however all would
suggest the potential for at least another advisory-type wind event
as this system passes by to our north Saturday into Saturday
night...with warning-criteria wind gusts not out of the question
should a more southerly (and closer) track ultimately verify.

Otherwise...the passage of this system is likely to bring another
round unseasonably mild temperatures (highs ranging through the 50s)
out ahead of the cold front Saturday...with the approach and passage
of the front also marked by some more rain showers. A quick shot of
colder air (but nowhere near as cold as behind the midweek system)
will then follow in its wake and then send temps back down into the
upper 20s and lower 30s Saturday night...and could briefly support
some limited lake effect rain and snow showers east of Lake Ontario.

&&

.LONG TERM /SUNDAY THROUGH MONDAY/...
High pressure over the Ohio Valley will build east into the Mid-
Atlantic on Sunday. What is left of any remaining lake effect will
all but wrap up by Sunday morning. This will occur as mid-levels
warm and equilibrium levels lower as the surface ridge moves into
and through the region. After that...all indication point to a rapid
warm up and wet weather returning on Monday. However...as was
previously mentioned there still remains some timing issues. That
said...have made some minor adjustments to NBM POPs to account for
this and also uncertainty with the strength of the surface low.
Otherwise...the wet weather looks like it will continue into the day
Tuesday and will be mild ahead of the cold front.

Wednesday and beyond...there are indications that winter will
potentially return behind the cold front. Guidance advertises that a
much colder air mass will spill out of Canada (-12C to -14C) across
the Great Lakes on Wednesday. This might be something too keep an
eye on for potential lake effect snow. But that`s way out there and
plenty can change. Stay tuned!

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
Widespread stratus with low VFR to MVFR bases will linger through
early this afternoon...before scattering out later this afternoon
and early this evening and giving way to increasing cirrus-level
cloudiness aloft. Fair dry weather and general VFR conditions will
then persist through the first half of tonight.

A strong cold front will then approach the region later tonight...
before crossing the area from west to east during the day Wednesday.
Out ahead of the front...widespread moderate rain will develop later
tonight and then will continue through the time of the frontal
passage...with the rain potentially becoming heavy at times east of
Lake Ontario during Wednesday. The rain will be accompanied by
steadily lowering ceilings...with these dropping into the IFR/lower
MVFR range across the higher terrain and to MVFR across the lower
elevations later tonight and Wednesday morning. This being said...
have aimed a bit above guidance for ceilings across the lower
elevations during this latter portion of the period as the guidance
typically is too pessimistic with ceilings in strong southerly
downslope flow regimes...as will be the case out ahead of this
front. Behind the front...strong cold air advection and increasing
mixing should then yield a general return to drier conditions and
MVFR/lower VFR ceilings from the Finger Lakes westward Wednesday
afternoon...though lake effect rain and snow showers will develop to
east of Lake Erie and affect locations south of KBUF.

The strong wind field accompanying the approach of the cold front
will also result in southerly winds becoming rather gusty across our
region tonight and Wednesday morning...with a 45-55 knot low level
jet inducing a period of low level wind shear at most of the
terminals. Additionally...the areas of most favored downslope flow
(along the Lake Erie shoreline near KDKK and immediately downwind of
the higher terrain of the Finger Lakes/Tug Hill) will likely see
surface wind gusts to 40-45 knots...with the same also likely in the
Black River Valley due to funnelling effects. Immediately following
the frontal passage... winds will then veer sharply from south to
west and rapidly increase as strong cold advection helps to mix
lingering higher momentum air from aloft down to the surface. This
will result in westerly winds gusting to 40-45 knots across much of
the lower elevations from late Wednesday morning through Wednesday
afternoon...with somewhat lower gusts of 30-40 knots expected across
the higher terrain.

Outlook...

Wednesday night and Thursday...Lake effect snow and local
IFR/LIFR east of the lakes...with VFR/MVFR and a chance of snow
showers elsewhere. Also continued windy conditions Wednesday
night and Thursday morning.
Friday...VFR.
Saturday...Mainly VFR and windy again with a chance of rain
showers.
Sunday...Mainly VFR.

&&

.MARINE...
A deepening area of low pressure will move from near Lake Superior
tonight to just east of James Bay by Wednesday night, with a strong
cold front sweeping across the lower Great Lakes late Wednesday.
Winds will strengthen and turn more southerly ahead of this system
tonight, leading to Small Craft Advisory conditions on the Lake Erie
nearshores, the Niagara River, and portions of Lake Ontario through
Wednesday morning.

Winds will become westerly on Wednesday as the front marches across
the lakes. Small Craft conditions on Erie will yield to gales by
Wednesday morning, then spreading across Lake Ontario Wednesday
afternoon. Gale force winds will then likely persist on Lake Erie
through late Wednesday night, and on Lake Ontario until Thursday
afternoon.

No change to the gale warnings in place, but issued Small Craft
headlines for the Niagara and St. Lawrence Rivers.

&&

.HYDROLOGY...
A period of rain will move into the area late tonight and
Wednesday ahead of a strong cold front. Increased runoff from
rain and any remaining snowmelt across central and southern Erie
County will again result in rises on the Buffalo area creeks
late Wednesday and Wednesday night. Creeks will likely rise to
action stage, with a low potential to approach minor flood if
there is still snowpack left to melt by Wednesday.

&&

.TIDES/COASTAL FLOODING...
West winds will increase to sustained 35-40 knots on Lake
Ontario Wednesday afternoon through Thursday in the wake of a
strong cold front. The combination of onshore winds and wave
action will bring a very low chance of limited lakeshore
flooding in low lying areas at the east end of Lake Ontario.
Lake levels are below normal, which may mitigate flood
potential.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Wind Advisory from 10 AM Wednesday to 1 AM EST Thursday for
     NYZ001-002-010-011.
     Wind Advisory from noon Wednesday to 1 PM EST Thursday for
     NYZ003>006.
     Lakeshore Flood Warning from 4 PM Wednesday to 4 PM EST
     Thursday for NYZ006-007.
     Lake Effect Snow Warning from 8 PM Wednesday to 7 PM EST
     Thursday for NYZ006>008.
     Wind Advisory from 4 AM Wednesday to 1 PM EST Thursday for
     NYZ007-008.
     Wind Advisory from 4 AM Wednesday to 1 AM EST Thursday for
     NYZ012>014-020-021.
     Winter Weather Advisory from 4 PM Wednesday to 1 PM EST
     Thursday for NYZ012-019-020-085.
     Wind Advisory from 10 PM this evening to 4 AM EST Thursday for
     NYZ019-085.
MARINE...Small Craft Advisory from 7 AM Wednesday to 7 AM EST Thursday
         for LEZ020.
         Small Craft Advisory from 10 PM this evening to 10 AM EST
         Wednesday for LEZ040-041.
         Gale Warning from 10 AM Wednesday to 4 AM EST Thursday for
         LEZ040-041.
         Small Craft Advisory from 7 AM Wednesday to 7 AM EST
         Thursday for LOZ030.
         Gale Warning from noon Wednesday to 4 PM EST Thursday for
         LOZ042>045-062>065.
         Small Craft Advisory from 1 AM to noon EST Wednesday for
         LOZ044-045.
         Small Craft Advisory from 10 AM Wednesday to 10 AM
         EST Thursday for SLZ022-024.

&&

$$

SYNOPSIS...Apffel/PP
NEAR TERM...Apffel/Hitchcock/PP
SHORT TERM...JJR
LONG TERM...AR
AVIATION...JJR
MARINE...Apffel/PP
HYDROLOGY...Hitchcock
TIDES/COASTAL FLOODING...Hitchcock


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.