Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221747

Area Forecast Discussion
National Weather Service Buffalo NY
147 PM EDT Sat Oct 22 2016

Rain will linger across the Eastern Lake Ontario region through
tonight, mixing with and changing to snow across the higher
elevations of the Tug Hill Plateau. Things will dry out Sunday
before another disturbance brings a chance of showers Sunday
night. Otherwise, cool northwesterly flow will keep temperatures
below average into the middle of the week, with a chance of lake
effect rain showers southeast of the lakes.


Precipitation tied to deformation zone will persist across the
North County through the afternoon. Snow mixing in at the highest
elevations of the Tug hill based on dual data and supported by
local web cams. A coating at best in these locations. To the west,
a cool northwesterly flow and lingering low level moisture will
also generate a response off the lakes, however with a shorter
fetch to work with and very dry air above 850mb, this response
will be mainly in the form of lingering cloud cover, along with
pockets of light rain or drizzle.

The cold air advection, along with a sharpening pressure gradient
between high pressure over the central Great Lakes and deepening
low pressure along the New England coast will result in
increasingly breezy conditions, with winds gusting up to 35 mph,
particularly near Lake Ontario and across higher elevations. The
abundant cloud cover, coupled with weak cold advection, means that
temperatures will climb little with temperatures only topping out
in the low to mid 40s.

Showers will continue into tonight across the eastern Lake Ontario
region as the wrap-around moisture on the western flank of the
departing low pressure system continues to slide across the area.
With temperatures across inland portions of the North Country
falling into the low to mid 30s, we may see precip change over to
snow across the higher elevations of the area, with an accumulation
of up to an inch possible across the highest portions of the Tug and
the Western Adirondacks overnight. Otherwise, expect plenty of lake-
effect cloudiness to persist elsewhere, though any precip will still
be limited to patchy drizzle, as the bulk of the moisture will be
confined to the lowest 5000ft of the atmosphere, with a strong
subsidence inversion above that level. Temperatures will fall into
the upper 30s in the Southern Tier, with lower 40s near the
lakes...though continued breezy west-northwest flow will still make
it feel quite raw.


A persistent cool northwest flow will occur across the eastern Great
Lakes through this period as an anomalously deep surface low
wobbles over eastern Quebec and a western Canadian sourced high
pressure builds southeast across the Northern Plains, western Great
Lakes and Midwest states. This flow will largely feature dry
continental air especially when compared to our recent extended
period of rainfall but models do show at least two plumes of
moisture working through the flow tied to separate shortwave
troughs. These shortwaves will be the focus for driving any
showers and associated lake effect through early next week.

Much of Sunday will feature dry weather with only a slight chance of
some sprinkles southeast of the lakes as moisture and synoptic lift
being to increase ahead of the first shortwave trough. This
shortwave is forecast to shift just to our southwest across Lake
Erie into PA Sunday night but models are showing a brief shot of
moisture extending northeast across much of our CWA. Have featured
chance POPs across the large majority of the CWA with likely POPs
focused over the western Southern Tier. Temperatures should remain
warm enough for p-type to be rain showers but there is a slight
chance that if the eastern extent reaches the Tug Hill and western
ADKs that some wet snow could mix in.

In the wake of this shortwave look for some dry time early Monday
before a shot of -3C to -6C air shifts over the Great Lakes. This
cooler air will drive up lake induced instability with Surface-850mb
delta Ts of around 20C eventually building Lake Induced Equilibrium
Levels up to around 20kft. A second weak shortwave and plume of
shallow moisture will shift over our area Monday night into Tuesday
morning. This should drive bands of lake effect showers southeast of
the lakes with the highest chance POPs coming between about Midnight
and Noon Tuesday. A 310-320 flow will keep most of the Lake Effect
showers limited to the southern shore of Lake Ontario into the
northern Finger Lakes off Lake Ontario and across Chautauqua county
off Lake Erie. Temps in the 40s by day will equate ptype to rain
showers but some wet snow could mix in across the higher terrain
Monday night as temps fall into the upper to mid 30s. The Canadian
sourced surface high over the midwest region Tuesday will build east
toward our region Tuesday night. This will drive down a capping
inversion bringing an end to Lake Effect overnight.


High pressure centered over Canada will extend southeast across the
Lower Great Lakes Wednesday and Wednesday night. This will support
mainly fair dry weather with temperatures within a few degrees of
normal. Meanwhile...a Pacific shortwave crossing the Rockies will
start the process of cyclogenesis over the Central Plains.

The forecast become very unclear for Thursday and Thursday night as
00z model guidance shows a large divergence of solutions between the
EC and GFS/CMC. The EC is an outlier tracking the Central Plains
surface low across the Great Lakes into southeast Ontario while the
GFS/CMC both show the low weakening/dissipating over the lower
Ohio/mid Mississippi river valleys. Due to this large spread in
forecast guidance have leaned heavily on the SuperBlend which
actually favors the EC solution. This puts chance POPs in play for
Thursday into Friday. Temperatures both Thursday and Friday should
top out in the low to mid 50s.


Cold air advection on northwesterly flow will continue to generate
MVFR cigs across the forecast area this afternoon, with IFR
conditions likely to persist across the higher terrain of the
Southern Tier and North Country. Expect gradual improvement across
Western New York after 21Z, as deeper low level moisture begins to
shift away to the east.

Lingering rain showers may change over to snow showers later
tonight across the higher elevations of the Tug Hill Plateau and
Western Adirondacks.


Sunday...MVFR/VFR. A chance for rain showers SE of the lakes.
Monday...Mainly VFR.
Tuesday...Mainly VFR.
Wednesday and Thursday ...VFR.


A surface low centered north of Cape Cod will deepen as it moves
north across Maine and into Quebec through tonight. The tightening
gradient between this low and a narrow ridge of high pressure
moving into the central Great Lakes coupled with increasing cold air
advection will allow northwesterly winds to freshen to gale force
tonight across central Lake Ontario, and appropriate warnings
remain in effect. Elsewhere, the brisk northwesterly flow will
keep small craft advisories in play well into Tuesday before high
pressure moves overhead Tuesday night into Wednesday.


The recent heavy rains have made a noticeable impact on area
rivers and streams, however given the antecedent drought
conditions, streams have had no flooding issues. The Allegany
River at Olean is currently cresting near action stage, while the
Black River will also be approaching action stage over the next 24
to 48 hours. However, with the bulk of the precipitation already
tapering off, no flooding issues are expected across the forecast


MARINE...Small Craft Advisory until 2 AM EDT Monday for LEZ041.
         Small Craft Advisory until 3 PM EDT Sunday for LEZ040.
         Small Craft Advisory until 8 PM EDT this evening for
         Gale Warning from 10 PM this evening to 11 AM EDT Sunday
         for LOZ062>064.
         Small Craft Advisory until 2 AM EDT Sunday for LOZ043-044.
         Gale Warning from 2 AM to 11 AM EDT Sunday for LOZ043-044.
         Small Craft Advisory until 11 PM EDT Sunday for LOZ042-045.
         Small Craft Advisory until 7 PM EDT Sunday for SLZ022-



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