Forecast Discussion

795
FXUS61 KBUF 040318
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1018 PM EST Tue Dec 3 2024

.SYNOPSIS...
Lake effect snow continues across areas southeast of Lake Erie
and Ontario late this evening with some additional accumulation,
but intensity of the snow has been considerably lower than over
the weekend. Lake effect snow bands will move north overnight
through early Wednesday, bringing a quick burst of snow and
minor accumulations to areas east and northeast of Lake Erie and
Lake Ontario. Low pressure will then pass just north of the
area Wednesday night through Thursday, with very gusty winds,
periods of snow, blowing snow, and possibly a few snow squalls.
The greatest accumulations will be east of Lake Erie and Lake
Ontario as lake enhancement develops.

&&

.NEAR TERM /THROUGH WEDNESDAY/...

The main concern through Wednesday morning will be the last of this
very long duration lake effect snow event. The intensity of snowfall
is not nearly as high as over the weekend, but still enough to have
some impact. Lake induced equilibrium levels will continue to run 12-
14K feet through this evening, before falling rapidly Wednesday
morning as warm advection aloft increases and inversion heights
lower. Backing of boundary layer flow to the southwest tonight
behind a weak mid-level trough passage has begun carrying lake
effect northward.

Off Lake Erie...

Lake effect snow has spread across much of the Southern Tier
this evening, but has been slowly shifting northward as the
low-level winds continue to back to the southwest. Latest GOES
imagery shows high clouds associated with a weak mid-level
trough passage that has aided in the the development of 850mb
southwesterly flow and eventual shift northward of snowbands
through the Buffalo area. Latest radar imagery as of 10 PM EST
shows a few snow showers reaching the Southtowns currently and
eventually lifting north through the city after midnight and
headed towards Wednesday morning eventually ending up in
Niagara County and weakening before daybreak. Snowfall rates may
still be moderate, but the rapid northward shift of the band
will likely limit accumulations to 1-3" overnight. The snow will
mostly be over by the start of the morning drive.

Off Lake Ontario...

A band of snow has reorganized over the lake this evening,
extending into Oswego County. As this trough continues to pass
to the east, expecting a similar response east of Lake Ontario
with snowfall lifting northward towards the Watertown area after
midnight. with backing boundary layer flow. Expect 2-4"
overnight through Wednesday morning as the band moves north
across the area. There may be some impact to the morning drive
in Jefferson County.

Wednesday, any lingering lake effect across Niagara County off Lake
Erie, and northern Jefferson County off Lake Ontario, will weaken
and mostly end through the morning hours as ongoing warm advection
continues to lower inversion heights. Our attention then turns
briefly back to the synoptic scale. Low pressure will track just
north of the upper Lakes, with a broad warm advection pattern
supporting a chance of some occasional light snow Wednesday.
Accumulation in most areas will be minimal from this. East of Lake
Ontario, increasing southwesterly upslope flow may produce a few
inches in the afternoon across the Tug Hill Plateau. More on this
event in the short term section below.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...

...IMPACTFUL WINTER STORM LIKELY WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT...

Low pressure will track across southern Ontario province Wednesday
night before moving across northern Maine on Thursday and then
strengthening to 973mb as it enters the Canadian Maritimes Thursday
night. This system will produce a hybrid snow event, with some
synoptic scale snow along with some lake effect and upslope enhanced
snow. Strong winds Wednesday night through Thursday night will
increase the impacts and cause areas of blowing snow.

An associated cold front will move across the area from west to east
late Wednesday night. This will produce an period of snow for all
areas, which may briefly be mixed with rain across some lower
elevations at its onset. Strong westerly winds will start
immediately following the frontal passage. 850 mb winds increase to
50 knots which will support widespread wind gusts to 40 mph with
gusts to 50 mph downwind of the lakeshores and across higher terrain.

Following the frontal passage, the mid level trough and 850mb temps
to -12C will support lake effect snow. Unlike our last event, the
strong westerly flow will not support banding, and moisture will
somewhat depend on upstream lakes and will be enhanced by orographic
lift. Adjusted snowfall forecast accordingly, favoring higher
resolution guidance during this phase. Since the strong westerly
flow will push lake/orographic snows into Allegany County have added
that to the winter storm watch.

The steadiest snows will be Wednesday night and Thursday, and then
will become more localized Thursday night. Storm totals are likely
to run in the 8 to 16 inch range across higher terrain east of the
lakes, with considerably less along I-90 which is near the
lakeshore. Lower elevations will get much less, averaging 3 to 6
inches. This will include the risk for snow squalls (heavy snow and
gusty winds) during the day on Thursday, as the upper level trough
moves through. Despite the lower snow amounts, this storm will be
very impactful because of the strong winds which will cause areas of
blowing snow. This will not only apply to the new snows, but also to
the snow which has already fallen in our last event. It also will
not be as localized as our last event, with at least some snow and
wind to cope with across the entire region.

Impacts will diminish Friday as winds drop off with gusts 20 to 25
mph. Lake effect snows will continue during the day, but with
limited moisture lake effect will depend on moisture connections
from upstream lakes. As a result snow will be more localized, but
will still have some impacts. Winds will shift to the southwest
Friday night, with whatever is left of the bands moving
east/northeast of the lakes. This will perhaps bring a little more
snow to the Buffalo metro area, although snow intensity and
amounts will be limited.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
It will be cold enough aloft to support some lingering lake effect
snow on Saturday. With the flow shifting to the southwest, snows
will move across the Niagara Frontier and Jefferson County, but the
moving band will only produce minor accumulations. Lake snows will
taper off Saturday night as warmer air aloft moves in. Warmer Sunday
and mainly dry with highs reaching into the 40s across lower
elevations.

Model consensus tracks low pressure to our north and west Monday and
Tuesday, which would result in a mainly, if not all rain event. Sill
some spread in model guidance, so depending on its track and
strength there`s some risk for mixed precipitation at the onset
Sunday night and Monday, but mainly across higher terrain and the
North Country. Otherwise it will be a fairly soaking rainfall with
ballpark rainfall amounts in the half inch to an inch. This combined
with snow melt will cause rises on creeks and rivers, but limited
rainfall amounts and recent dry weather support MMEFS ensembles
which show only a low risk (less than 20 percent) for flooding.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...

Lake effect snow showers have been working their way back across the
Southern Tier early this evening with winds backing to the
southwest. This has produced IFR conditions near KJHW over the
past few hours and should continue through 02z this evening
before snow bands work their way northward towards KBUF and KIAG
for later tonight and early Wednesday morning. Latest HREF
guidance shows probabilities of IFR ceilings and visibility
increasing after 05z with snowfall expected for a couple hours
over these terminals headed towards daybreak. Snowfall from this
band could reach as far east as KROC, but greater uncertainty
exists farther east on the degree of potential intensity and
resulting reductions to visibility. Similar situation tonight
east of Lake Ontario with ongoing lake effect snow bands
shifting northward overnight towards KART after 06z with IFR
conditions expected to persist through the early morning hours.
Gusty southwest winds will develop through Wednesday afternoon
ahead of the next approaching system with additional snow
showers beginning by mid-afternoon and continuing into Wednesday
night.

Outlook...

Wednesday night...Areas of IFR/LIFR in snow showers and heavier
pockets of snow, especially east/northeast of the lakes. Very windy.

Thursday...Areas of MVFR/IFR in snow showers. Heavier lake effect
snow east of the lakes with local LIFR. Very windy.

Friday...VFR/MVFR with scattered snow showers. Localized IFR in
lingering lake effect snow showers southeast of the lakes.

Saturday...VFR/MVFR with a chance of snow showers.

Sunday...Mainly VFR

&&

.MARINE...
Northwest winds will continue to produce choppy conditions on Lake
Erie and Lake Ontario into the evening, but winds and waves will
generally stay below Small Craft Advisory criteria.

Winds will start to increase out of the southwest on the lakes later
in the evening from west to east as the pressure gradient increases
over the region with an area of low pressure approaching from the
northwest and a sfc high to the south. This will prompt the need for
Small Craft Advisories which will then transition to Gale Warnings
that are in effect for times listed below.

Moderately strong low pressure will then pass just north of the
lakes later Wednesday through early Thursday before a secondary
coastal low deepens over the Canadian Maritimes Thursday night. This
will cause the Gale conditions on Lake Erie Wednesday through
Thursday, and Lake Ontario early Thursday through Thursday night.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Storm Watch from Wednesday afternoon through late
     Thursday night for NYZ006>008.
     Winter Storm Watch from Wednesday evening through late
     Thursday night for NYZ012-019>021-085.
MARINE...Small Craft Advisory from 4 AM Wednesday to 1 AM EST Friday
         for LEZ020.
         Small Craft Advisory until 7 AM EST Wednesday for LEZ040-
         041.
         Gale Warning from 7 AM Wednesday to 7 PM EST Thursday for
         LEZ040-041.
         Small Craft Advisory from 4 AM Wednesday to 1 AM EST
         Friday for LOZ030.
         Small Craft Advisory from 4 AM Wednesday to 4 AM EST
         Thursday for LOZ042>045.
         Gale Warning from 4 AM Thursday to 1 AM EST Friday for
         LOZ042>045-062>065.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Brothers/Hitchcock/SW
SHORT TERM...Apffel
LONG TERM...Apffel
AVIATION...Brothers
MARINE...Hitchcock/SW

NWS BUF Office Area Forecast Discussion