Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 210010

Area Forecast Discussion
National Weather Service Buffalo NY
810 PM EDT Tue Mar 20 2018

High pressure centered over northern Ontario will maintain dry and
chilly weather through the end of the week. Temperatures will begin
to rise by early next week as the deep trough over the Northeast
begins to move off the east coast.


Strong Canadian surface high pressure centered over northern Ontario
will only slowly pivot east across James Bay through Wednesday...with
ridging extending southward over the Great Lakes. This will keep the
latest in a series of Nor`easters at bay to our south...with the far
northern edge of its light snow closely approaching but also likely
remaining south of the NY/PA border tonight. Otherwise mainly clear
to partly cloudy skies across the region early this evening will become
partly to mostly cloudy south of Lake Ontario tonight as mid and high
clouds increase to the north of the Nor`easter...with some limited lower
clouds also becoming possible across portions of the Niagara Frontier
overnight due to a continued northeasterly low level flow. With the
increasing cloud cover and persistent northeasterly breeze...lows
tonight should not be as cold as last night...with lows mostly ranging
from the lower to mid 20s south of Lake Ontario to 10 to 15 across
the North Country.

The winter storm will shift off the Mid-Atlantic coast on Wednesday
while high pressure to our north continues to keep dry weather for
Western and North-Central NY. Partly to mostly cloudy skies, mainly
mid-high level will linger much of the day associated with the
northern edge of the winter storm. Any Lake Effect clouds in the
morning over the Niagara Frontier should breakup with daytime
heating. Winds will back to the north over the eastern Great Lakes
as the storm shifts off the coast. Expect another windy day with a
tight pressure gradient over our region with winds 15-25mph. The
northerly flow will keep temperature well below normal. Highs only
expected in the low to mid 30s but the winds will make it feel more
like upper teens to low 20s.


For the latter half of the week, low pressure will remain well to
our east, tracking from the Gulf of Maine to the Canadian Maritimes.
Meanwhile, Canadian high pressure will remain anchored south of
James Bay. This configuration will keep cool and mainly dry weather
in place across our region.

Temperatures aloft will be cold enough for some lake enhanced
cloudiness, however dry boundary layer air will limit the potential
for lake effect precipitation. On Thursday night and Friday, a
shortwave is forecast to move across the region embedded in the
western fringe of a broadly cyclonic flow aloft. This colder air
aloft may support some light lake/and or instability enhanced snow
showers south and east of Lake Ontario Thursday night and Friday.

Outside of this...the vast majority of the period will be simply dry
with below normal temperatures. High temperatures will remain the
30s each day, with nightly lows ranging from the upper teens to mid


This period is shaping up to be largely uneventful, with high
pressure initially to the west of our region, passing over the area
Sunday and Monday with sun-filled days...and then working its` way
to our east Tuesday.

Meanwhile the storm in the southern branch of the jet stream that at
one point threatened our region with snow this now
tracking well to our south across the Tennessee Valley. While clouds
from this system may brush by us Saturday, its` precipitation shield
should stay just to our south.

A shortwave in the northern branch of the jet stream will drop
across NY/NE Sunday. While this feature will pass across our region
dry it will rapidly deepen the southern storm system into a major
coastal low off the eastern shoreline. Where this happens is still
in question. A close to the shore development early next week will
likely to hold off any frontal boundaries/rain showers/warmth to our
west through at least Tuesday, while development farther out to sea
will allow for warmer air coupled with rain showers to expand across
our region Tuesday.

Temperatures below/near normal through at least Sunday...before
southerly winds behind the surface high pressure bring the prospects
for above normal warmth (mid/upper 40s) possibly by next


Surface high pressure will remain centered across northern Ontario
through tonight before pivoting to James Bay through Wednesday...
while keeping a Nor`easter at bay to our south and east. VFR flight
conditions will thus largely prevail with just some increase in mid
and high cloud cover expected from the Nor`easter tonight into
Wednesday morning...though some lower lake-induced clouds cannot be
totally ruled out across portions of the Niagara Frontier late tonight
and early to mid Wednesday morning. Otherwise a general northeasterly
flow will remain in place...with this increasing some again during
the day Wednesday as diurnal heating/mixing resumes.

Wednesday night through Saturday...Mainly VFR. A chance
of Lake Effect snow south/southeast of Lake Ontario Thursday night
and Friday.
Saturday night and Sunday...Mainly VFR with a chance of snow.


Low pressure will strengthen off the Mid Atlantic coast tonight into
Wednesday...before moving slowly northeastward offshore of the New
England coast Wednesday night and Thursday. The pressure gradient
between this low and high pressure over northern Ontario will continue
to produce moderate northeasterly/northerly winds on Lake Ontario and
Lake Erie, leading to a prolonged period of advisory-worthy conditions
along the south shores of both lakes.

The above said...have cancelled the advisory for the Upper Niagara
River and Buffalo Harbor with surface obs indicating that winds there
have consistently remained a bit below advisory levels there so far...
and the latest guidance also suggesting that these are unlikely
to be any higher during either tonight or Wednesday.

Additionally...the persistent northeasterly flow continues to displace
and/or break up the existing ice cover over eastern Lake Erie...which
remains a hazard to anyone attempting to venture out onto the ice.


MARINE...Small Craft Advisory until 5 PM EDT Wednesday for LEZ040-041.
         Small Craft Advisory until 8 PM EDT Wednesday for
         Small Craft Advisory until 2 PM EDT Thursday for



LONG TERM...Thomas
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