Area Forecast Discussion Issued by NWS Buffalo, NY
000
FXUS61 KBUF 180229
AFDBUF
Area Forecast Discussion
National Weather Service Buffalo NY
1029 PM EDT Sun Mar 17 2024
.SYNOPSIS...
Cold air will deepen across the region this week, with several
passing surface troughs producing occasional rounds of snow showers,
graupel, and lake effect snow tonight through Thursday. The greatest
snow accumulations will be found across the higher terrain east of
Lake Erie and Lake Ontario. The snow will most readily stick from
around sunset through mid morning each day, with some melting during
the daylight hours due to the high March sun angle. Temperatures
will run below average through the end of the week.
&&
.NEAR TERM /UNTIL 6 PM MONDAY EVENING/...
Water vapor imagery displays several shortwaves over the Upper
Midwest that will deepen an upper level trough over the Great Lakes
this week. As this trough deepens and slides towards our region, a
deepening cold airmass will generate bands of lake effect snow off
both eastern Great Lakes by Monday morning.
Radar imagery showing a few areas of snow showers late this evening.
The last of the diurnal snow showers are drifting east across the
Finger Lakes and Central NY, gradually diminishing in coverage with
time. Lake enhanced snow showers are expanding across Chautauqua
County, and a few lake effect snow showers are developing southeast
of Lake Ontario from Sodus Bay to southern Oswego County. All of
this is disorganized for the time being.
Continued cold air advection will drop 850 hPa temperatures to -10C
towards Monday morning to allow for lake effect snow to continue to
develop. With the deeper synoptic moisture arriving later tonight,
lake response should be minor with just an inch or two of snow
tonight across the higher terrain east of Lake Erie and across the
Tug Hill Plateau east of Lake Ontario. Confidence is low on this
snow late tonight and Monday morning as we are marginally cold
enough aloft, and the deeper synoptic moisture will just be arriving
over the Lakes. Several operational models, including the 12Z GFS,
Canadian, HRRR as well as the NBM do indicate several inches of snow
falling by Monday morning east of Lake Ontario.
Temperatures aloft may actually warm a degree or two Monday, that
with the March sun angle will trend lake snows to more cellular in
nature as deep diurnal mixing interferes with the delicate
circulations that drive bands of lake effect snow. This will hold
back on snow accumulations through the day to some extent. Expect a
spotty inch or so for the higher terrain east of Lake Erie, and 2-4"
for the Tug Hill Plateau.
By tomorrow night synoptic moisture will have deepen sufficiently
that with strong CAA aloft and steepening lapse rates lake effect
snow should once again increase in intensity east of both Lakes. The
approach of a secondary surface trough from Canada will enhance low
level convergence with greater snow accumulations east of Lake
Ontario, than east of Lake Erie, where some wind shear will allow
the snow bands to oscillate. East of Lake Erie additional snow
should amount to 1 to 3 inches, while additional snow amounts of 4
to 6 inches are possible on the Tug Hill.
Will issue a winter weather advisory for the eastern Lake Ontario
region, mainly for the Tug Hill, from early Monday morning through
early Tuesday morning. Within this broad time window, the best snow
accumulation and greatest impact is expected to be late Monday
afternoon through Monday night.
Overnight lows will be in the 20s, while tomorrow will feature near
and below normal temperatures in the mid to upper 30s. These values
tomorrow will be some 15 to 20 degrees colder than what the region
has averaged the first half of March.
&&
.SHORT TERM /6 PM MONDAY EVENING THROUGH WEDNESDAY NIGHT/...
On and off snow showers and cool weather will be the main theme
moving through mid-week. A shortwave trough will approach the region
on the backside of a departing trough Tuesday. Boundary layer flow
will back to the southwest and will likely cause ongoing lake effect
snow showers to move north towards the Northtowns east of Lake Erie
and the Tug Hill east of Lake Ontario. Warm air advection will take
place ahead of an approaching surface low pressure/surface trough.
While lake induced instability will become marginal east of Lake
Erie by Tuesday afternoon, forcing from the surface low and
approaching trough will intensify snow showers across the region.
Daytime highs will reach the upper 30s to low 40s and any snow
accumulation will likely be confined to the higher terrain east of
the Lakes. Breezy conditions will result in wind chill values in the
20s Tuesday.
The surface reflection will move across the forecast area Tuesday
night. This will disrupt the wind field across the region with
weakening snow bands. Falling temperatures will allow snow to
accumulate across the region, however there is uncertainty in snow
placement Tuesday night. The NAM is showing a stronger surface low
and snow ahead of this system, with lake effect snow forming east of
Lake Erie whereas the RGEM keeps lake effect and upslope snow on the
Tug Hill and lesser amounts east of Lake Erie. The global models and
ensemble systems show a higher probability of snow continuing east
of Lake Ontario. While snowfall amounts could be higher especially
on the Tug Hill Tuesday night, sided with consensus and have minor
accumulations at this time.
Fortunately, there is good agreement that another shot of cold air
moves into the region behind the surface trough Wednesday. The
wintry pattern continues aloft with another, more robust shortwave
trough moving down from the Upper Great Lakes region. Winds will
ramp up across the region with the PV 1.5 pressure surface lowering
to 500mb. Breezy conditions expected with gusts 30-40mph,
potentially higher along the eastern Lake Ontario shoreline.
Temperatures aloft will fall to -12C across the region and unstable
conditions will lead to snow showers across the region. Lake
enhanced snow showers with possible upstream connections could
produce localized heavier snow showers. High temperatures will reach
the low to mid 30s across the higher terrain to the upper 30s across
the lake plains. Highest chance for snowfall accumulation will be
across the higher terrain. Wind chills will stay in the 20s before
falling into the teens by evening. Cold Wednesday night with lows in
the upper teens to low 20s and wind chills in the single digits.
Snow showers will continue within northwest flow across the region.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
Winter like pattern for at least the start of the long term period.
While the long term period won`t be as cold as some days we have had
this winter, it will be among the coolest vs climatology, especially
for Thursday where afternoon highs of 10 to 15 degrees below normal
are expected for most of the area. Temperatures in the mid 20s to
mid 30s for the day on Thursday will slowly warm on Friday to the
upper 20s to low 40s. Still plenty of uncertainty with the weekend
among the guidance and therefore the weekend temperatures, but new
guidance is starting to come in colder, so will take that into
account for the weekend Max Ts and adjust them down some.
Models seem to be in fairly good agreement that lingering lake snow
showers will continue into Thursday south and southeast of the
lakes, tapering off through the day. Thursday afternoon and most of
the night dry out as a weak ridge and quick sfc high pass by before
another batch of showers approach.
A weak warm front tracking across the area brings the next chance
for snow showers (mixing with rain at times) Friday morning, with
the trailing cold front/trough continuing the precip into the
morning on Saturday.
There will be the potential for a lake response off of both lakes
from Saturday morning into Saturday night, but model disagreement
becomes more evident from Saturday morning onward. The GFS brings a
colder airmass with 850H temps dropping to -12 to -18 C for
Saturday, while the Canadian is much warmer only dropping the 850H
temp to around -9C briefly. This is in part because the Canadian
also places the main portion of the mid-level trough and low farther
north and looks to move the main trough through quicker.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A few areas of scattered snow showers will continue to drift across
the area from late evening through the early overnight. Most areas
will be VFR, but any of the snow showers will contain brief/local
MVFR to IFR conditions.
Late tonight and Monday cold air will continue to deepen, supporting
increasing lake effect snow east of Lake Erie and Lake Ontario.
Strong diurnal mixing from the high March sun angle will likely
break apart the lake effect snow into convective snow showers from
late morning through early evening, with any of the heavier snow
showers producing brief/local IFR/LIFR VSBY and MVFR CIGS. Outside
of lake effect areas, general snow showers will increase Monday
afternoon with local IFR as a trough and deep moisture cross the
region.
Outlook...
Monday night through Wednesday...Occasional lake effect snow showers
with local/brief IFR conditions. MVFR/VFR outside of lake effect.
Thursday...MVFR/VFR with a chance of snow showers and associated
brief/local IFR.
Friday...Mainly VFR.
&&
.MARINE...
Small craft advisories are in place throughout the Lower Great
Lakes...as a deep cyclonic flow will maintain fresh to strong winds
through at least Monday evening. During this period...gale force
gusts will be possible on the eastern half of Lake Ontario.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 5 AM Monday to 5 AM EDT Tuesday
for NYZ006>008.
MARINE...Small Craft Advisory until 8 PM EDT Tuesday for LEZ040-041.
Small Craft Advisory until 8 PM EDT Tuesday for
LOZ042.
Small Craft Advisory until 5 AM EDT Wednesday for
LOZ043>045.
&&
$$
SYNOPSIS...Hitchcock/Thomas
NEAR TERM...Hitchcock/HSK/Thomas
SHORT TERM...HSK
LONG TERM...SW
AVIATION...Hitchcock
MARINE...Thomas