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Area forecast discussion 
National Weather Service Buffalo New York
1000 am EST Sat Feb 6 2016

some limited lake effect snow will continue northeast of Lake
Ontario today with minor accumulations. Otherwise mainly dry weather
is expected for the rest of the region today through Sunday. An area
of low pressure will move very slowly across the Great Lakes Monday
through Wednesday with periods of snow. Temperatures will grow
steadily colder behind this system late next week with a strong
cold front bringing more snow on Friday.


Near term /through tonight/...
at 1000 am radar shows some light lake enhanced snow showers
north of I-90 from buf-roc. This has developed in advance of a
shortwave which is moving east which provides confidence that this
will be short-lived and only produce a dusting. Mesoscale guidance
captures this to some degree...but consensus is underdone. The
best chance for accumulation will be near the Lake Ontario
shoreline where a mesoscale convergence band may clip the south
shores and bring an inch before the shortwave moves east of
Rochester this afternoon. Will monitor this convergence band...but
based on mesoscale guidance it probably focus in Canada or just
clip the Thousand Islands region. Following this...only expect
light accumulations 1-2 inches east of Lake Ontario...mainly areas
north of Watertown. Infrared satellite and model guidance both show
much drier air behind the shortwave which should end snow showers
this afternoon from west to east. The only other change to the
forecast is to briefly increase winds behind the shortwave.

The combination of moisture from the shortwave and southwesterly
flow has developed a band of lake effect snow across southern Erie
County. This will be short lived...ending once the shortwave
departs and drier air moves in. Localized accumulation of an inch
is possible late this morning roughly form lackawana to Alden.

Otherwise for the rest of the area warm advection in the middle levels
and moisture off the lakes will produce plenty of cloud cover
through early afternoon...with some clearing developing from
southwest to northeast this afternoon from western New York to The Finger
lakes. Temperatures will remain on the mild side with highs in the
upper 30s on the lake plains and lower 30s on the hills. Central New York
should eclipse 40.

Any scattered light snow showers across the north country will end
early this evening. The north country will remain mostly cloudy
overnight with ongoing warm advection clouds and lake effect clouds.
Western and central New York should see at least partial clearing as the
deeper moisture retreats to north of the international border.
Expect lows in the upper 20s to around 30 on the lake plains and
lower to middle 20s across the interior southern tier valleys and Tug
Hill region.


Short term /Sunday through Tuesday/...
on Sunday... a surface front will remain stalled near the Saint
Lawrence River. Light south or southwest winds across much of the will be another mild and dry for much of the area with
temperatures in the upper 30s to lower 40s. There should be mainly
high clouds with partial sunshine. The surface front should finally
make some southward progress into the north country on Sunday as
northeast/easterly flow develops in response to the pressure falls
ahead of the next approaching storm system over the upper Great
Lakes. This will keep daytime highs limited to the middle 30s across
the Tug Hill plateau and upper Saint Lawrence valley...along with a
low chance for some weakly forced snow showers along the boundary.

Sunday night... the forecast area will be caught between an
encroaching stacked low pressure system over the upper Great Lakes
and a coastal low tracking northward off the eastern Seaboard. In
the middle we will see some weak upper level ridging and a low-level
northeasterly flow from a surface high over Quebec keeping a dry low-
level flow into the area. This will keep much of the overnight
Sunday dry... with temperatures near 30 across western New York and
slightly cooler (in the middle 20s) closer to the surface high in the
north country.

By Monday into Tuesday an upper level low will be stalled across
Michigan while another shortwave carves out a deep trough into the
southeast Continental U.S.. this will result in a secondary surface low
developing near Cape Hatteras and tracking along the East Coast. The
main impact of this coastal storm on our weather will be to keep the
best upper-level dynamics and moisture transport away from the area.
Consequently we will remain back in the cooler airmass with
disorganized light snow across the area as moisture / forcing
remains limited. For chance of snow will be across
western New York (west of the Genesee valley) due to the proximity to the
low pressure system. Initially...BUFKIT soundings show a marginal
temperature profile... with a chance for a wintry mix of
rain/sleet/snow at the onset of precipitation... but partial
thicknesses support a transition to all snow despite marginal
surface temperatures by later Monday. Little if any snow
accumulation is expected on Monday when precipitation changes to all
snow due to marginal temperatures... very light precipitation rates
to limit dynamical cooling and solar insolation even through the
clouds. Monday night... light snow will spread across the region...
with the chance for light accumulations from a coating to an inch in
the north country and lake plains to one to three inches across the
higher terrain of the western southern tier. Details become more
murky Tuesday as snowfall will depend on tracks of subtle shortwave
pivoting around the stalled mean trough and the interaction with the
coastal low. Have continued high chance probability of precipitation... with the expectation
that scattered areas of light snow showers will prevail across the
region. Temperatures Monday into Tuesday will remain in the 30s
during the day and 20s at night.


Long term /Tuesday night through Friday/...
it continues to look increasing likely that two main pushes of
Arctic air will surge across the forecast area in the extended with
much below normal temperatures and increased likelihood of long-
lasting lake effect snows mainly east-southeast of the lakes.

By Wednesday into Thursday... behind the departing coastal storm and
mean upper-level trough axis shifting across the forecast area...
the first surge of colder air arrives. Back trajectories on this
airmass... which global models are growing increasing confident on
its timing into the forecast area late Wednesday through Thursday...
show it originates from the Canadian Arctic. The GFS/ec/Gem and
their ensembles show 850 mb temperatures around -20c across western
and central New York. This will promote surface temperatures in the single
digits and teens Wednesday night through Thursday night.
Also...model agreement is good in a west to northwest flow which
will promote lake effect snows southeast of the lakes likely
starting Wednesday night and persisting through the day Thursday.

By late Friday through Saturday night a reinforcing shot of Arctic
air is looking increasingly likely to impact the northeast Continental U.S..
GFS/ec guidance continues to trend toward bringing this colder push
of Arctic air... which model back trajectories show originates near
Siberia and evolves into the northeast Continental U.S. Via cross-polar flow in
the highly amplified pattern. Should 00z GFS/ec consensus forecast
850 mb temperatures near -30c materialized by Saturday... this
airmass would likely challenge daily record cold temperatures with
highs in the low single digits to near zero and lows below zero.
While model consensus and ensemble support gives some confidence in
this cold airmass... the details will likely change given this event
is still a week away. However... the bottom line is that below to
much below normal temperatures remain possible through the middle of
February with increasing chances of lake effect snows mainly east-
southeast of the lakes.


Aviation /15z Saturday through Wednesday/...
some light snow is possible at buf/roc/iag late this
morning...resulting in a brief period of MVFR conditions. Some
light snow and areas of modest lake enhancement northeast of Lake
Ontario will bring spotty IFR this morning including kart. This
snow will weaken to scattered light snow showers this afternoon
with visibility returning to mainly VFR. Areas of MVFR ceilings may continue
as lake effect clouds linger.

Otherwise for the rest of the area expect VFR to prevail with clouds
through early afternoon giving way to at least partial clearing late
this afternoon and tonight. More clouds will linger through tonight
northeast of Lake Ontario with mainly VFR ceilings at lower elevations
and MVFR across higher terrain.

Monday...VFR deteriorating to MVFR/IFR in periods of snow.
Tuesday and Wednesday...MVFR/IFR in periods of snow.


moderate southwesterlies across lakes Erie and Ontario will continue
today into this evening as the pressure gradient tightens between a
cold front moving across Ontario and Quebec and a surface high over
the Middle Atlantic States. This will maintain Small Craft Advisory
conditions on both lakes.

The surface pressure gradient will weaken over the lower Great Lakes
late tonight and Sunday as the region will be situated between a
storm system over the upper Great Lakes and one off the middle Atlantic


Buf watches/warnings/advisories...
New York...none.
Marine...Small Craft Advisory until 4 am EST Sunday for lez040-041.
Small Craft Advisory until 10 am EST Sunday for
Small Craft Advisory until 4 am EST Sunday for loz042.



near term...apffel/Hitchcock

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