Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 131750

Area Forecast Discussion
National Weather Service Buffalo NY
1250 PM EST Wed Dec 13 2017

A cold northwesterly flow will result in continued lake effect snow
and blowing snow across the region today. A short break is possible
this coming evening before another weak system moves into the region
tonight. Yet another system with both some lake effect and
widespread snow will move in by Friday and last through least part
of the weekend.


Northwest flow in the wake of a departing surface low over the Gulf
of Maine continues to drive multi-banded lake effect snow over the
southern lakeshores. Snowfall rates have diminished considerably
with diminishing moisture as this system continues to move
further away. Based on this, have dropped a portion of the
warnings and advisories but maintain others. At this point, the
majority of the snow is due to lake effect, and it is low
topped. As a result, it is expected that bands far away from the
radar will not be well sampled and that snowfall rates may be
more impressive than what radar seems to indicate.

Off Lake Erie, multiple bands persist late this morning and
should last into early afternoon. Winds will diminish and shift
this afternoon with a singular convergence band expected to form
late this afternoon. This should largely be over the open waters
but may clip portions of Chautauqua county. Additional
accumulation of 1 to 3 inches is expected in most persistent
snows this afternoon.

Off Lake Ontario, multibanded snow also continues across the
southern lakeshores in northwest flow. These will continue to
produce locally heavy snow through early afternoon but then
snowfall rates should taper off as progressively drier air moves
in. Additional accumulation of up to 2 inches this afternoon.
There also will be areas of blowing snow with gusts up to 35

The arctic airmass will keep cold temps in place today. Highs
will only reach the mid teens to low 20s for WNY but only mid
teens east of Lake Ontario. Lingering northwest breeze will hold
wind chills within a few degrees either side of zero.

A clipper, shifting southeast across Minnesota this morning is
forecast to reach the Ohio Valley later today then shift south of NY
across PA tonight. Weak synoptic forcing in the presence of
plentiful 925-700 mb moisture on the north side of the clipper will
bring a widespread light snow across Western NY and Finger Lakes
tonight. Any lingering weak Lake Effect southeast of Lake Ontario
should be overtaken by forcing from the synoptic scale clipper snow
by midnight. The eastern Lake Ontario region is expected to miss out
on this system tracking to the south. The arctic airmass with
surface temps dipping into the low teens to single digits tight
should support SLR of 20:1 or better. Blended QPF ranging from 0.05-
0.15 should yield around an inch across the Finger Lakes with 2 to
perhaps as high as 4 inches for WNY. No headlines are expected for
these light amounts. The clipper will create light and variable
winds over our region overnight so wind chills will be negligible.


The clipper system will be moving off the Jersey coast Thursday
morning and associated moisture will be moving away from
Western/Central NY. High pressure will move across the Ohio Valley
Thursday and NW flow is expected across the eastern Great Lakes. Dry
conditions upstream and low inversion heights will limit lake effect
snow showers Thursday afternoon. As winds back and become more
westerly Thursday night into Friday, moisture will increase off the
long fetch of the lakes. Lake effect snow showers will increase
however accumulations will be minimal as dry mid-level air keep
bands weak until moisture returns Friday.

A closed low will drop south across Ontario Friday and an associated
surface low will move across the northern Great Lakes. Winds will
back further and warm air advection aloft will produce snow showers
across the region. As the closed low becomes an open wave Friday
night, strong lift and lake enhancement will likely produce heavy
lake effect snow downwind of the lakes. There is uncertainty as
to where the best placement of these lake bands will be at this
time but favorable conditions exist for possible
advisory/warning criteria downwind of the lakes.

Temperatures warm slightly Friday with temperatures in the mid 20s.
Cloud cover and snow showers will keep temperatures fairly steady
into Friday night.


A ridge builds in Saturday in the wake of a trough passage Friday
night. With cold air and moisture in place Saturday morning behind
the trough, lake effect snows will be ongoing downwind of the
eastern Great Lakes. However, the ridge and warm advection quickly
move in during the day Saturday, which will shut down any lingering
lake snows.

With downstream blocking finally relaxing a bit, the persistent cold
air that we`ve been experiencing is expected to lessen a bit. This
should allow for temperatures to begin moderating over the weekend
and into early next week. Some areas may even see temperatures a bit
above normal. The pattern however remains fairly active, shortwaves
will provide a few chances for snow showers, and possibly some mixed


Lake snows south of the lakes will continue to diminish through
mid-afternoon. This will result in patchy IFR/MVFR vsby in lake
snows but these should mainly be away from our TAF sites. A
clipper low will bring a general light snow to areas south of
Lake Ontario. Very cold temperatures will result in small
snowflakes which will likely lower vsby to 1-2 SM for a 3-6 hour
period tonight as the system moves through. Expect a weak lake
enhancement Thursday morning behind the system with snow showers
lingering southeast of the lakes through mid-morning. Otherwise
expect conditions improving to VFR late morning and early


Thursday through Sunday...Several systems will move across the
region over the course the the week and weekend with both widespread
snow and localized lake effect with resulting IFR conditions.
There will be several periods of VFR between systems.
Monday...Mainly VFR. A chance of snow showers.


A deepening surface low continues to move northeast across Eastern
Maine this morning as an anomalously deep upper level trough plows
into the lower Great Lakes region. Behind the low, multi-banded lake
effect snow in northwest flow will continue into today. Small craft
advisory conditions continue on Lake Ontario and Lake Erie through


NY...Winter Storm Warning until 7 PM EST this evening for
     Lake Effect Snow Warning until 7 PM EST this evening for
MARINE...Small Craft Advisory until 7 PM EST this evening for LEZ040-
         Small Craft Advisory until 4 AM EST Thursday for
         Small Craft Advisory until 7 PM EST Thursday for LOZ044-



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