Forecast Discussion for BUF NWS Office
FXUS61 KBUF 121108

Area Forecast Discussion
National Weather Service Buffalo NY
608 AM EST Tue Dec 12 2017

Low pressure will push east across our area today...with widespread
light to moderate snow this morning giving way to a prolonged period
of lake enhanced and lake effect snow east and southeast of the
lakes from this afternoon on through Wednesday.


Low pressure draped from near Georgian Bay to western Pennsylvania
will consolidate and slide eastward across New York State today.
Out ahead of this system...warm air advection/isentropic upglide
will continue to generate widespread light to occasionally moderate
snow through much of this morning...with most areas picking up an
additional 1 to 3 inches of accumulation or so through midday. This
said...orographically-induced enhancement will lead to some areas of
locally higher accumulations along south facing slopes of the higher
terrain east of Lake Ontario.

Following the passage of the low center and its attendant cold
front...a general westerly flow of much colder air will pour across
the region through the balance of the day...with 850 mb temps
dropping into the negative teens across the majority of the area by
early this evening. Coupled with sufficient synoptic background
moisture remaining in place...this will allow increasingly lake-
driven and/or lake-enhanced snows to develop east of both lakes...
with this enhancement beginning as early as this morning off Lake
Erie...and during this afternoon off Lake Ontario. Outside of the
areas where lake processes will come into play...the synoptically-
driven snows will temporarily diminish to some scattered light snow
showers following the passage of the cold front...with this trend
most likely to be noticeable across portions of the Niagara Frontier
and interior sections of the Finger Lakes Region...where only scattered
light snow showers are expected this afternoon. Additional snowfall
amounts this afternoon should range from 1-3"/2-4" in the favored
areas of lake/orographic enhancement east of the lakes to under an
inch elsewhere. Temperature-wise...readings will largely peak in the
upper 20s to mid 30s out ahead of the cold front/surface low...before
giving way to steadily falling readings through the balance of the day.

Tonight the main surface low will track further eastward into
Maine...while circulating a trailing secondary cold front across
the region this evening. The approach and passage of the secondary
front will encourage the redevelopment of widespread light to
moderate snow across the region from northwest to southeast. At the
same time...the boost in moisture and lift provided by the secondary
front will also help to intensify the areas of lake effect/lake
enhanced snow...which will also shift southward to areas southeast
of the lakes as the low level flow veers more northwesterly following
the passage of the boundary. Additional snowfall accums tonight will
likely range from 5-10 inches within the most persistent regions of
lake effect/lake enhanced snows to another general 1 to 3 inches
elsewhere...with the heaviest snows focusing along the Chautauqua Ridge
east of Lake Erie and also from Monroe county over to the Tug Hill
Region east of Lake Ontario. The additional snowfall will also be
compounded by increasing westerly to northwesterly winds...which will
produce areas of blowing and drifting snow. Otherwise...we can expect
a much colder night with continued cold air advection helping send
temperatures down into the teens areawide.

Given current forecast expectations through changes
to the existing winter weather headlines are necessary at this time.


The Eastern Great Lakes will be on the backside of an upper level
trough Wednesday. Scattered snow showers will be ongoing Wednesday
as moisture wraps around departing low pressure. Lake enhancement is
expected with heavier snow southeast of the lakes. Light
accumulations are expected across the region with light to moderate
accumulations expected in persistent lake bands. Additional
accumulations of 1-3 inches are expected during this time.

Moisture will move away from the region Wednesday night and snow
showers will become less widespread. Lake bands will likely persist
through Thursday as W-NW flow over the lakes continues however mid-
level moisture will become sparse and accumulations will diminish
by Thursday morning. A shortwave trough and associated clipper
system will move into the Ohio Valley Wednesday night. A brief
period of light winds is expected across western and central NY and
temperatures will drop into the teens overnight. Wind chills in the
single digits are expected into Thursday morning.

Most of the attention will be to the south of the eastern Great
Lakes Thursday as the clipper moves across the Mid-Atlantic region.
Snow showers may skirt across the Southern Tier Thursday morning but
would mainly be light. W-NW flow over the lakes will continue
Thursday-Thursday night. A low inversion height and mid-level dry
air will keep accumulating snow to a minimum during this time.


Cold and active pattern will persist into Friday and Saturday as
several more lower amplitude shortwaves progress through the
longwave trough in place across the eastern CONUS. The result will
be additional snow shower chances, with the better chance arriving
late Friday into Saturday as a surface low cuts across the Great
Lakes. This system could bring a general minor accumulating snow.

A deamplifying flow pattern will bring in some slightly milder air
by Sunday and Monday, but will also open the door for stronger
pacific energy to bring a more widespread/heavier, possibly mixed
precipitation maker through Great Lakes Sunday. Models are all over
the place at this time range resulting in a low confidence forecast
belong Saturday.


Low pressure draped from near Georgian Bay to western Pennsylvania
will consolidate and slide eastward across New York State today...
before pushing on to Maine tonight. Widespread light to occasionally
moderate snow out ahead of this system this morning will give way to
increasing amounts of lake enhanced/lake effect snow east and southeast
of the lakes following the passage of the low this afternoon and

In terms of flight conditions...general IFR conditions will largely
prevail through tonight...though there should be a break in the snow
across portions of the Niagara Frontier and Finger Lakes regions
from this afternoon into very early this evening...which should
result in some temporary improvement to MVFR/VFR at the KBUF/KIAG/
KROC terminals for a time.

Wednesday...Areas of LIFR/IFR in lake effect/lake enhanced snow east
and southeast of the lakes...with IFR in morning snow elsewhere
improving to MVFR/VFR in more scattered snow showers.
Thursday through Saturday...Areas of MVFR/IFR in scattered to
numerous snow showers east and southeast of the lakes...otherwise


Low pressure draped from near Georgian Bay to western Pennsylvania
will consolidate and slide eastward across New York State today.
Generally light to modest winds out ahead of this system will quickly
veer to westerly and sharply increase today following its passage...
then will become northwesterly tonight. This will bring a prolonged
period of at least advisory-worthy winds and waves areawide...with
winds on eastern Lake Erie even briefly increasing to low-end Gale
Force late this afternoon and this evening.


NY...Winter Storm Warning until 7 PM EST Wednesday for NYZ003>008.
     Winter Weather Advisory until 1 PM EST Wednesday for NYZ001-
     Lake Effect Snow Warning until 7 PM EST Wednesday for NYZ012-
MARINE...Small Craft Advisory until 4 PM EST this afternoon for LEZ040-
         Gale Warning from 4 PM this afternoon to 4 AM EST
         Wednesday for LEZ040-041.
         Small Craft Advisory until 1 AM EST Thursday for LEZ020.
         Small Craft Advisory until 4 AM EST Thursday for
         Small Craft Advisory from 10 AM this morning to 7 PM EST
         Thursday for LOZ044-045.




NWS BUF Office Area Forecast Discussion