Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 140609

Area Forecast Discussion
National Weather Service Buffalo NY
209 AM EDT Wed Mar 14 2018

A strong area of low pressure will move across the Gulf of
Maine overnight resulting in light to occasionally moderate
snowfall across western and north central New York through
Wednesday. Snow combined with gusty northwest winds will result
in some blowing and drifting on Wednesday. Moderate snow
Wednesday night will taper off to lighter activity Thursday and


A large upper level low is centered across western NY this
evening with an impressive Nor`easter east of Maine. For our
area, the most significant feature will be an inverted trough which
extends along the south shores of Lake Ontario this evening.
Overnight, snow should have a bit easier time accumulating.
In general expect 2 to 5 inches of snow overnight. Slightly higher
amounts are possible due to upsloping across higher terrain south
and east of the lakes, with slightly less to the south where
moisture from the trough will not arrive until late in the night.
Model guidance shows these trends fairly well, with the forecast
favoring and/or enhancing orographic effects since some guidance
lacks the resolution to capture this.

The pressure gradient will tighten across the region
as the coastal low moves north into Nova Scotia. This will lead
to stronger winds and blowing snow overnight reducing
visibilities at times.

Snow continues Wednesday as the upper level low moves over
southeastern NY. Northwest winds will slightly back across the
region. Upslope flow and synoptic moisture will lead to accumulating
snow across the region. Snowfall accumulations will be greatest and
most impactful over the higher terrain where boundary layer
temperatures remain below freezing. Northwest winds will increase to
15-25 mph with gusts as high as 40-45mph. Higher gusts expected
along the southern lake shore of Ontario. Blowing snow is expected.

Temperatures will drop to the 20s tonight. On Wednesday, temps
will stay in the 20s at higher elevations and rise into the low
30s elsewhere.


Typical late winter high latitude blocking will keep cold snowy
weather in place across our region through this forecast period. We
can ultimately put the blame for this weather on persistent ridging
over the Norwegian Sea which will prevent a stacked low from
advancing out of Quebec/Canadian maritimes. The latter will support
continued snows over our region...while a staunch high amplitude
ridge over the Rockies will maintain a northerly flow that will
continue to drain sub-arctic air out of the polar vortex over
the Canadian Archipelago. This will keep our temperatures below
normal. If you want day to day on.

A closed mid level low in the vcnty of Cape Cod Wednesday evening
will drift to Nova Scotia overnight while capturing its Nor`easter
surface reflection. This general synoptic set up will keep a deep
cyclonic flow over our forecast area...where a northwest upslope
flow will provide the bulk of lift necessary for generating
continued widespread light to moderate snow. A short lived swath of
drier mid level air will traverse the region overnight...and this
should briefly temper the areal coverage and intensity of the on
going snow. Otherwise...the most concentrated snowfall will be found
east and southeast of Lake Ontario where stronger upslope in the
vcnty of the Tug Hill and lake enhancement will be at a maximum.
Wednesday night snowfall amounts will range from less than an inch
across parts of the Niagara Frontier to 3 to 6 inches on the Tug

On Thursday...some dry mid level air wrapping around the stacked low
will help to minimize the intensity of the snow showers. The
exception will be southeast of both lakes (esp Lake Ont)...where
lake enhancement will add moisture to the low levels. As we have
been stressing in the various products...after a slick early
morning start...a high March sun angle will greatly limit any
impacts to travel as the day progresses. Daytime snow accumulations
will range from less than inch across the lake plains to 1 to 3
inches across the higher elevations of the Southern Tier and east
of Lake Ontario.

A cold front will drop south across the forecast area Thursday
night. Colder air in its wake will encourage synoptic based...lake
enhanced snows to transition to pure lake effect as low level lapse
rates will finally exceed 7 deg c/km. Guidance continues to
underplay the extent of the scattered snow showers outside of the
lake effect. Will generally use high chc pops for these areas...
while cat pops will be maintained southeast of the lakes.

While the stacked low will continue to meander over the Canadian
maritimes Friday and Friday night...surface high pressure will start
to muscle its way across the Great Lakes region. Notably drier air
will accompany this feature...and with a gradual loss of a cyclonic
flow aloft...snow showers will continue to taper off. This will
especially be the case friday night when the bulk of the
synoptic moisture will be stripped away from the region. That
being said...a cold northwest flow over Lake Ontario will keep
some snow showers in place for sites between Rochester and the
Tug Hill plateau.


High pressure will be in the process of building at all levels into
the Eastern Great Lakes to start this period. Lake enhanced snows
south and southeast of the lakes will be shutting down as drier air
filters into the mid/low levels and subsidence squashes any further
snow shower development across the region. Saturday should be the
nicest day of the period with fair and dry weather. Although, highs
on Saturday will still likely average a few degrees below climo for
this time of year.

Saturday night, models show two well defined shortwaves riding
through the developing split flow aloft with the northern stream
shortwave slicing across Ontario/Quebec Canada and the other through
the Tennessee valley. The northern stream shortwave will drag a cold
front across the Lower Great Lakes Sunday. This cold front will
bring in another shot of very cold air across the forecast area for
early next week. Infact, highs on Monday if the Ecmwf verifies will
likely not make it above freezing with H850 temperatures nearing
-18C to -20C. There will be a chance of a few snow showers and
flurries east of lake Ontario into the North Country Sunday
afternoon as this system passes by. Otherwise, most of the forecast
area will remain dry throughout the weekend. Surface high pressure
over the Canadian Prairies will build south and southeast into Great
Lakes region Sunday. Meanwhile, cyclogenesis will occur over the
Midwest as a 120kt jet streak crosses the Rockies. This surface low
will track east Monday and is forecast to pass well to the south of
the Lower Lakes on Tuesday. It look right now to have little impact
on our region outside of some clouds across the Southern Tier. Look
for surface high pressure to maintain dry weather with highs well
below climo into the first part of the week.


Expect widespread snow across the region today with a long stretch
of IFR conditions likely at all TAF sites. Snow will taper off from
west to east Wednesday afternoon through Wednesday evening with
conditions improving to MVFR and eventually VFR. Northwest winds
will increase this morning, with gusts of 25 to 30 kts today. Some
areas of blowing and drifting snow are possible.


Wednesday night and Thursday...A mix of IFR/MVFR/VFR in scattered to
numerous snow showers...which will be most persistent/numerous
southeast of the lakes.
Friday...VFR/MVFR with scattered snow showers southeast of the lakes.
Saturday and Sunday...VFR.


A coastal low will move across the Gulf of Maine overnight.
Northwest winds in response to this low will continue to
increase tonight supporting widespread small craft headlines.

Winds are expected to peak tomorrow, nearing 30 knots along the
southern Lake Ontario shoreline.

As the coastal low departs to eastern Canada, the pressure gradient
will relax some, likely ending small craft conditions for most areas
by Thursday afternoon.


NY...Winter Storm Warning until 8 AM EDT Thursday for NYZ006>008.
     Winter Weather Advisory until 6 AM EDT Thursday for NYZ003>005-
     Winter Weather Advisory until 2 AM EDT Thursday for NYZ001-002-
     Winter Storm Warning until 2 AM EDT Thursday for NYZ012-019-
MARINE...Small Craft Advisory until 2 AM EDT Thursday for LEZ040-041.
         Small Craft Advisory until 11 PM EDT this evening for
         Small Craft Advisory until 5 PM EDT Thursday for
         Small Craft Advisory from 6 AM this morning to 5 PM EDT
         Thursday for LOZ045.



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