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Area forecast discussion 
National Weather Service Binghamton New York
642 PM EST Tuesday Feb 9 2016

a series of cold fronts will move across the area during the next
few days. The first front will bring a light snow to much of the
area tonight. Scattered showers will continue Wednesday especially
near the southeast shore of Lake Ontario where a few additional
inches may accumulate. Arctic air will overspread the area
Wednesday night into Friday along with snow showers. Several
inches will accumulate near Lake Ontario into Friday with a couple
of inches possible southward to southern New York and northern


Near term /through Wednesday/...
530 PM update...increased probability of precipitation/qpf/snow amts along a broad line
of snow showers currently tracking through central New York. Have had
reports of 1 to 3 quick inches of snow with this band and the
latest rap/hrrr and nam12 continue to bring this line to around
the I-81 corridor by middle to late evening before dissipating.

Previous discussion...
low pressure will track east from the eastern Great Lakes to
northern New York this evening. A trough will extend southward
from the low down to northern PA. Scattered snow showers
developing over the central Finger Lakes this afternoon are
forecast by all high resolution and short range models to combine
into an area of light to moderate snow along the trough by early
this evening... with this area of snow then forecast to move
across the area tonight. Expect most places to pick up around an
inch of snow from this system. Snow showers will diminish to
flurries overnight as the trough pushes east.


Short term /Wednesday night through Friday night/...
a middle-level trough will track east across the area during the day
Wednesday with cyclonic west-northwest low-level flow. Expect numerous snow
showers with this feature across central New York during the day
Wednesday with scattered snow showers across southern New York
and far northern PA. Model soundings showing lapse rates around
7.0 degrees c/km through 600 mb with some very minimal cape values.
High resolution 4 km NAM shows the development of some fairly
impressive cellular snow showers during the afternoon with this
system. The regional Canadian model... which has been very good
with lake effect snow this year... shows the development of lake
enhanced banded features over central New York by middle to late afternoon.
Based on these signals we are expecting some snow showers during
the day Wednesday and maybe a heavier squall or two during the
afternoon over central New York. 850 mb temperatures will be around -8 c
which will not be cold enough for true lake effect snow...
although some lake enhancement could still occur. These snow showers
could put down a quick couple of inches in spots and as such we
have decided to start Our Lake effect Snow Advisory Wednesday
afternoon. Colder air will arrive Wednesday night and Thursday
with lake effect snow organizing in earnest during that time.

Temperatures quickly fall below -10 c at 850 mb Wednesday
evening and as such we expect some fairly well-organized lake
effect snow bands to develop southeast of Lake Ontario during that
time. The 4 km NAM... Canadian regional and locally developed
analog program all indicate that multiple bands of lake effect
snow will develop southeast of Lake Ontario with a flow direction
from around 290-295 degrees. Models are all indicating that the
flow will be shifting enough so that we are not expecting a
persistent band to set up in any one location long enough for
heavy snowfall... however we do expect some 4 to 6 inch type
amounts over the northern third of the forecast where bands are a
little more persistent.

A secondary Arctic front looks to drop south across the area early
Thursday followed by some truly cold air with 850 mb temperatures
falling to around -22 c Thursday afternoon. Expect multi-bands of
lake effect snow from 300-305 degrees during this time. The
atmosphere will be drying out as the Arctic air comes in but still
expect this pattern to support at least a few more inches
southeast of Lake Ontario and the advisory will continue through
the day Thursday.

The flow will shift to west-southwest Thursday night as the next
Arctic front approaches from the northwest. Based on this expect
lake effect snows to shift north of Onondaga County by early
Thursday night and north of the entire forecast area overnight.
This next Arctic front is forecast to drop south across the area
on Friday probably accompanied by some snow squalls possibly all
the way down to northeast PA. The coldest air of the season will
follow behind this front Friday night with a renewal of lake
effect snows south-southeast of Lake Ontario on north-
northwesterly winds.


Long term /Saturday through Tuesday/...
the main story for the long term will be the bitter cold for this
weekend. Forecast models in great overall agreement on 500 mb
trough and associated upper low dropping into the the NE with
1000-500 mb thickness prognosticated to only be around 490 dm and 850 mb
temperatures around -30 c...about as cold as is seen around here. We
initialized forecast with model blend known as the superblend but
made some deviations...going even slightly colder than this
guidance for temperatures Saturday and also raising the probability of precipitation due to
expected lake effect.

In terms of day to day details, core of coldest air will be
advecting into the area Saturday on bitter northwest flow. Highs will
only be in the single digits with wind chills making it feel even
colder. There will be at least some lake effect snow however it
will actually be so cold entire profile will be colder than
dendritic snow growth zone which will be a limiting factor
despite extreme instability. Due keep likely probability of precipitation for snow showers
in for Seneca east through Cayuga and Onondaga counties with
chance probability of precipitation for much of the remainder of County Warning Area.

Saturday night will be the coldest night with widespread subzero
lows expected...possibly even minus double digit lows, especially
in eastern zones north through Oneida County. Winds look to stay
up due to continuing gradient between low to the east and high to
the west and this will make it feel even colder but may act to
limit temperatures from bottoming out to really extreme values.

For Sunday, only some moderation expected compared to Saturday as
Arctic high slides east right over the area by late day. Still
expect some lake effect, though this will tend to be diminishing
through the day has the high moves in. Highs look to range from
the single digits through much of the Catskills north to the Tug
Hill with low to middle teens elsewhere.

Pattern will be progressive enough for core of Arctic air to move
out early next week with more significant moderation back to at
least seasonal. Models indicate the next upper trough moving into
the east with low pressure development but there is model
disagreement on timing, track, and intensity. For now, indicate
chance of snow in grids for Monday and Tuesday but there's a
chance low could track far enough west to bring rain to some areas
by Tuesday.


Aviation /00z Wednesday through Sunday/...
a large stacked low pressure area over the western Great Lakes
and Ohio Valley will move gradually east through Wednesday. This
gradual movement will provide a variety of flight restrictions
and timing issues for the next 24 hours.

For this evening, a band of snow moving east across central New York as
well as additional snow moving into NE PA will bring IFR visbys to
all sites this evening. A break is expected as this band moves out
through the latter part of this evening into the overnight with
conditions improving at least to MVFR ceilings and VFR visibilities.
Additional snow bands with IFR visibility/MVFR ceiling restrictions become
likely again after 12z Wednesday...mainly across the cny flight
operations area with less effect nepa.

Winds generally light and variable tonight becoming west 8-10
knots with some higher gusts for Wednesday.


Thursday through sun...variable ceiling and visibility restrictions due to
periods of widespread light snow and bands of more intense lake
effect snow...especially northern half. Less coverage and time
affected for the southern areas.


Bgm watches/warnings/advisories...
New York...Lake effect Snow Advisory from 1 PM Wednesday to 7 PM EST
Thursday for nyz009-016>018-036-037-044>046.


near term...bjt/mse
short term...mse
long term...pcf

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