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Area forecast discussion 
National Weather Service Buffalo New York
704 PM EST Sat Feb 13 2016

Synopsis...
the coldest airmass of the season will remain in place through
Sunday morning as bitterly cold air combines with a noticeable wind
to produce dangerously cold wind chill values. Widespread mainly
light lake effect snow showers will continue southeast of the lakes
through Sunday morning before slowly diminishing Sunday afternoon.
Temperatures will return to near average early next week with a pair
of systems possibly bringing some light snow to the region Monday
through Wednesday.

&&

Near term /through Sunday/...
Lake effect snow will continue tonight through the first half of
Sunday. Lake induced instability will peak early this evening with
equilibrium levels in the 10-12k feet range...then steadily drop
through Sunday morning as middle level temperatures begin to warm and a
subsidence inversion strengthens and lowers. Despite the strong
instability initially...a short northwest fetch and very dry airmass
will limit accumulations. In addition...the temperatures in the
cloud layer are too cold for dendrites...with very small snowflakes
being produced which are not efficient at accumulating. The low
density small snowflakes will also allow for plenty of blowing and
drifting snow through the rest of the afternoon and first half of
tonight before winds diminish.

Off Lake Ontario...

Expect a wide spray of lake effect snow showers from Niagara to
Oswego counties through the first half of tonight. Snow showers will
occasionally extend inland across the northern Finger Lakes as well.
Overnight expect the lake snow west of Rochester to slowly taper off
as high pressure and subsidence begin to build over the western end
of the Lake. Lake effect snow will last longer from the eastern
suburbs of Rochester to Oswego County...with the latest mesoscale
model guidance suggesting modest accumulating snow will last through
late morning Sunday before tapering off as high pressure builds
over the eastern half of the lake.

Expect additional amounts of 2 inches or so tonight west of
Rochester and up to 3 to 4 inches east of Rochester where lake
effect snow showers will last longer and be more persistent.
Areas east of Rochester may pick up another 1-2 inches Sunday
morning before the lake snow weakens by midday. With this in mind
have extended the lake effect Snow Advisory for Monroe...Wayne...
northern Cayuga...Oswego counties through 1pm Sunday. The advisory
for Niagara and Orleans County runs through 1am Sunday.

Off Lake Erie...

Lake effect snow will remain weak through early evening and focus
mainly across Chautauqua and Cattaraugus counties with a very short
fetch across Lake Erie and little upstream help from Lake Huron.
Latest mesoscale model guidance suggests boundary layer flow will
back enough to possibly bring the Lake Huron upstream connection
from northwest PA back into Chautauqua County for a few hours this
evening. This may bring better snowfall rates and coverage back with
2-3 inches possible in portions of Chautauqua County. This upstream
connection should break down after midnight as high pressure
approaches Lake Erie. With this in mind the lake effect Snow
Advisory will continue through 1am Sunday for Chautauqua County.

Temperatures will remain frigid with lows around 5 below on the lake
plains of western New York...being held up by lake modification and lake
effect clouds. The interior southern tier will drop to 10 to 15
below especially if any breaks in the clouds develop overnight. The
north country will have no lake influence which will allow the
bottom to drop out with lows of 20 to 30 below. Wind chills will
continue to run 20 to 30 below across much of the region...and as
low as 40 to 45 below across the north country.

On Sunday the frigid temperatures will continue through the morning
before the coldest airmass retreats during the afternoon. Expect
highs in the high single numbers to low teens across western New York...
with single digits above and below zero east of Lake Ontario. Winds
will be relatively light with high pressure overhead...bringing an
end to the bitterly cold wind chills.

&&

Short term /Sunday night through Tuesday night/...
focus for the first half of next week will be on the amplification
of a Pacific based middle-level trough and potential for development of
a winter storm tracking south then east of our forecast area. As
this trough digs into the deep south Monday night and Tuesday a
leading shortwave is forecast to cross the Great Lakes which could
touch of a weak surface low or surface trough leading to increasing
chances of light snow late Sunday night into Monday.

By Monday night and Tuesday models agree on the development of a
surface low over the southern Appalachians which will track somewhere
north along or just east of The Spine of the Appalachians. 12z GFS
and Gem models keep the track of the surface low along the I-95
corridor while the 12z ec tracks the low further west across the
Adirondacks. The east solution would keep our forecast area on the
cold side of the low with a p-type of all snow...while the ec
solution may spread some warm air aloft over central New York
leading to a potential for mixed precipitation or even plain rain
for a short time. Given the fairly good agreement of the thermal
profiles of the European model (ecmwf) and GFS Monday night and Tuesday...have
added the chance for some sleet for portions of the southern tier
northeastward across parts of The Finger lakes to the Eastern Lake
Ontario region.

Tuesday night...the various guidance packages converge on lifting
the low north of Maine with some wrap around moisture allowing for
a chance of snow showers across western and central New York.

In terms of temperatures...Sunday night will still be quite cold
with lows ranging through the low single digits for most into the
negative single digits for the North County. An increasing south to
southeasterly flow ahead of the developing surface to our south will
help temperatures warm into the middle 20s Monday and Monday night up
to the middle 30s on Tuesday. As the low shift north across New England
cold advection will cool temperatures Tuesday night back into the middle 20s.

&&

Long term /Wednesday through Saturday/...
trailing the Tuesday storm...lingering troughiness will keep chances
for winter weather in place midweek then a wavy zonal Pacific middle-
level flow looks to set up across the Continental U.S. Late in the week. This
Pacific flow will eventually seal off any Arctic air to the north
with temperatures then warming to above normal. On Wednesday...a
trailing weak clipper or surface trough looks to cross the Great
Lakes bringing a brief shot of colder air and chances for some light
snow showers. There may even be some lake enhancement southeast of
the lakes into Wednesday night as lake induced equilibrium levels
briefly climb to between 5 and 10kft.

Dry conditions are expected Thursday followed by a return to above
normal temperatures late in the week as low pressure tracks across
the Great Lakes. This latter system will also bring renewed
precipitation chances to our region...with any precipitation likely
changing over from snow to rain as the atmospheric column warms on
Friday and Friday night followed by an changeover back to chances
of snow Saturday with cooler flow in the wake of the low.

&&

Aviation /00z Sunday through Thursday/...
a bitter cold northwest flow will continue to generate light lake
snows south and southeast of both lakes...where MVFR to IFR
conditions will be in place through the night. Much of this will be
due to lower visibilities in snow. Even kbuf and kiag will experience
MVFR to occasional IFR conditions as streamers from the upper Great
Lakes will make their way into the area. Only kart and the north
country will experience mainly VFR conditions through the night.

Later tonight and Sunday morning lake effect snow will diminish
southeast of Lake Erie and at the west end of Lake Ontario with
conditions slowly improving to MVFR and then VFR. Lake effect snow
will persist longer southeast of Lake Ontario...with areas of IFR
through midday Sunday from just east of kroc to kfzy. This too will
slowly end Sunday afternoon with improvement to MVFR and eventually
VFR.

Outlook...
Monday...VFR/MVFR with a chance of light snow.
Monday night and Tuesday...MVFR/IFR with snow likely possibly mixed
with rain in the afternoon.
Wednesday...MVFR/IFR with a chance of snow.
Thursday...mainly VFR.

&&

Marine...
a brisk flow of progressively colder Arctic air will continue across
the lower lakes region this evening before gradually weakening late
tonight and Sunday. Small Craft Advisory conditions will continue
through Sunday morning before high pressure builds over the lower
lakes and brings diminishing winds during the day Sunday.

The frigid airmass will combine with brisk winds and result in heavy
freezing spray on both lakes Erie and Ontario...for which heavy
freezing spray warnings will be in place through early Sunday
morning.

&&

Climate...
an Arctic airmass will be dropping across our region...with near
record breaking cold lasting through the weekend. Below are some
climate stats and records regarding this weekend.

Buffalo:

Coldest temperatures last winter: -10f February 15th and 16th

Record low Saturday February 13th: -9f 1914
record low Sunday February 14th: -13f 1943

Record low maximum Saturday February 13th: 5f 1899
record low maximum Sunday February 14th: 5f 1979

Rochester:

Coldest temperatures last winter: -11f February 20th and 21st

Record low Saturday February 13th: -12f 1979
record low Sunday February 14th: -14f 1979

Record low maximum Saturday February 13th: 9f 1979
record low maximum Sunday February 14th: 6f 1979

Watertown:

Coldest temperatures last winter: -36f February 16th

Record low Saturday February 13th: -28f 1979
record low Sunday February 14th: -30f 1979

Record low maximum Saturday February 13th: 1f 1979
record low maximum Sunday February 14th: -1f 1979

&&

Buf watches/warnings/advisories...
New York...wind chill warning until 10 am EST Sunday for nyz001>008-
010>014-019>021-085.
Lake effect Snow Advisory until 1 PM EST Sunday for nyz003>006.
Lake effect Snow Advisory until 1 am EST Sunday for nyz001-002-
019.
Marine...heavy freezing spray warning until 7 am EST Sunday for lez040-
041.
Small Craft Advisory until 1 am EST Sunday for lez040-041.
Heavy freezing spray warning until 7 am EST Sunday
for loz042>045-062>065.
Small Craft Advisory until 1 PM EST Sunday for loz043>045.
Small Craft Advisory until 4 am EST Sunday for loz042.

&&

$$

Synopsis...Hitchcock
near term...Hitchcock/rsh
short term...rsh/Smith
long term...Smith
aviation...Hitchcock/rsh
marine...Hitchcock
climate...Thomas

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