Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 271131
AFDBUF

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

.SYNOPSIS...
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
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
IR satellite imagery showing a veil of thin cirrus level cloudiness
spreading north across Western NY early this morning. An area of mid
level clouds is also expanding over and east of Lake Ontario, with
mainly clear skies elsewhere. The high clouds will continue to
overspread the area from southwest to northeast this morning,
although a good deal of sun should still filter through. The mid
level clouds east of Lake Ontario will continue to expand as a
weak surface trough moves southeast across Ontario.

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 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.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
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.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Some clouds will develop this 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 at lower
elevations and MVFR across higher terrain. Elsewhere high/thin
cirrus level cloudiness will overspread the area from southwest to
northeast. Mid level clouds will also increase across 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.

Outlook...

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.

&&

.MARINE...
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.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ040-
         041.
         Small Craft Advisory until 10 AM EST this morning for
         LEZ020.
         Small Craft Advisory until 4 PM EST this afternoon
         for LOZ043>045.
         Small Craft Advisory until 1 PM EST this afternoon for
         LOZ042.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...CHURCH
LONG TERM...CHURCH
AVIATION...HITCHCOCK
MARINE...HITCHCOCK



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