Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 271454

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

Weak high pressure will bring mainly dry weather through tonight. A
warm front will then bring an increasing risk of showers on Tuesday...
before more widespread rain develops 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 week.


Surface-based ridging will prevail across the Lower Lakes Region
today...supporting continued dry weather. Skies will also tend to
be mostly sunny for much of the area...though there will be a couple
of exceptions. The first of these will lie across the North Country...
where a dying surface trough will continue to generate some clouds
through early to mid afternoon. The other will be across the Southern
Tier...where mid level clouds will gradually increase this afternoon
as warm air advection increases ahead of a weak Ohio Valley wave.
As for temps...ongoing low level warm advection will support highs
in the mid to upper 40s for most areas...along with a few lower 50s
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 across the region today...with most
areas seeing a good deal of sunshine. This said...mid level clouds
will be more common across the North Country through early to mid
afternoon in association with a dying surface trough...while another
area of mid level clouds spreads into the Southern Tier this afternoon.

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 continue to 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. 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 4 PM EST this afternoon for
         Small Craft Advisory until 1 PM EST this afternoon for



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