Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 270841

Area Forecast Discussion
National Weather Service Buffalo NY
341 AM EST Mon Feb 27 2017

Weak high pressure will bring mainly dry weather through tonight. A
warm front will then produce a few scattered showers Tuesday before
more widespread rain later Tuesday night and Wednesday as low
pressure moves through the Great Lakes. Temperatures will be well
above normal through Wednesday before colder air arrives late in the


IR satellite imagery showing mainly clear skies early this morning
with just a few patches of mid level clouds supported by a weak warm
advection regime.

High pressure will drift east off the Mid Atlantic coast today with
a weak ridge extending into the Lower Great Lakes and supporting
continued dry weather. Meanwhile a weak mid level trough will move
east across Quebec, with an associated weak surface trough glancing
the North Country. This surface trough, combined with some
contribution of lake moisture, will bring some cloud cover to the
eastern Lake Ontario region from mid to late morning through mid
afternoon. Mid level clouds will also increase later today across
the Southern Tier as warm advection increases ahead of a weak Ohio
Valley wave. Otherwise the rest of the area will see a good amount
of sunshine with just a few passing patches of mid level clouds.
Ongoing low level warm advection will support highs in the mid to
upper 40s for most areas, with a few low 50s readings in the
normally warmer spots of the Genesee Valley and Finger Lakes.

Tonight the weak mid level wave in the Ohio Valley will ripple off
the Mid Atlantic coast, with a wing of weak mid level warm advection
spreading north through PA to Central NY. The warm advection and
associated isentropic upglide will bring an increase in cloud cover
from south to north tonight. The ascent may be just enough to
squeeze out a few flurries or sprinkles from the interior Southern
Tier to the Finger Lakes and Central NY later tonight. The increase
in clouds will limit radiational cooling, with lows in the mid 30s
in most areas and upper 20s North Country.


On Tuesday, broad troughing carved out across the western CONUS will
bring steadily rising heights with broad ridging to the east coast.
A wave of low pressure will track from the central Great Plains
toward the upper Great Lakes on Tuesday. This will help to push a
warm frontal boundary north across the region, bringing a return
much above temperatures for mid-week, as well as a batch of
precipitation on the nose of the best moisture advection ahead of
the low. Instability along the warm front will be marginal, but
marginally steep mid-level lapse rates would favor some isolated
elevated thunderstorms. Temperatures will top out in the 50s for
most locations.

Tuesday night into Wednesday, as secondary, stronger, wave of low
pressure will track along the baroclinic zone draped from the
central Plains to the lower Great Lakes. This will bring added warm
air advection, along with much stronger moisture advection and
synoptic lift. This will result in more widespread showers Tuesday
night in Wednesday, that will likely come in a few rounds: 1/ on the
nose of the best moisture advection Tuesday night, then perhaps a
pre-frontal trough Wednesday morning and again with the strong cold
frontal passage Wednesday afternoon. Thunderstorms will also be
possible, and while overall instability will be marginal, the
strongly forced and high shear environment could result in a few
strong storms capable of producing bowing segments with damaging
wind gusts. In fact, SPC has included the area in a marginal risk
for severe weather on Wednesday, in the latest day 3 outlook. Will
continue to mention this in the HWO. Expect temperatures to remain
near steady then rise overnight Tuesday night, while topping out in
the upper 50s to mid 60s across the region Wednesday.

Rapid cold air advection in the wake of the surface front passage
late Wednesday may allow for a brief change over to some snow
showers before precipitation tapers off Wednesday evening.
Otherwise, strong synoptic wind gusts are also possible late
Wednesday the increasing cold air advection and subsidence in the
wake of the passing deepening low will help to get some stronger
gusts to surface. There remains some uncertainty with how strong
these winds would be, as the surface low may not really start to
strengthen until is pulling well away from the region, and this would
limit the strength of the winds aloft to mix to the surface.
However, it is possible a wind advisory may be needed for the
typical wind prone lake plains, and thus will continue to mention in
the HWO. Temperatures will sharply fall back into the upper 20s to
low 30s through Wednesday night returning our weather back to more
wintry pattern.


Winter conditions will return for the end of week into the weekend
as a deep progressive trough brings a surge of colder air across the
northeast CONUS. Weak shortwaves may affect the region in the
developing northwest mid/upper level flow. Confidence is getting
higher that enough cold air will slide into the area for increasing
northwest/west-northwest flow lake effect snows from late Thursday
into Friday night as 850 mb temperatures drop to around -18C by
Friday night. A stronger Pacific shortwave and surface low moving
into the upper Great lakes will bring increasing warm air advection
later Saturday and Sunday with precipitation chances diminishing
along with moderating temperatures into the 40s by Sunday.


VFR conditions will prevail today into this evening. Some clouds
will develop from mid morning through mid afternoon east of Lake
Ontario as a weak surface trough glances the North Country, with
CIGS staying in the lower end of the VFR category. Mid level clouds
will also increase across the Southern Tier later today. A weak mid
level wave will pass by to the south of the area tonight, with warm
advection bringing a south to north increase in mid level clouds.
Conditions will remain VFR in most areas, but model soundings
suggest enough low level moisture across the Southern Tier to allow
a low stratus deck to develop across the higher terrain with MVFR
CIGS. There may be just enough lift to produce a few sprinkles or
flurries overnight from the interior Southern Tier into the Finger
Lakes and Central NY, with VSBY remaining VFR.


Tuesday...VFR/MVFR with a chance of showers.
Wednesday...MVFR/IFR with periods of rain.
Thursday and Friday...Areas of MVFR with a chance of snow showers.


Southwest winds will gradually diminish today as the pressure
gradient relaxes across the Lower Great Lakes. This will allow wind
and wave conditions to drop below Small Craft Advisory criteria from
west to east today. Winds will then remain light tonight through
most of Tuesday.

Stronger winds will return Tuesday night and Wednesday as a stronger
area of low pressure moves into the Great Lakes region. The moderate
to strong winds will then continue Wednesday night through Thursday
as this low pressure deepens further over eastern Quebec.


MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ040-
         Small Craft Advisory until 10 AM EST this morning for
         Small Craft Advisory until 4 PM EST this afternoon
         for LOZ043>045.
         Small Craft Advisory until 1 PM EST this afternoon for



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