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Area forecast discussion 
National Weather Service Buffalo New York
756 PM EDT Wednesday Sep 17 2014

Synopsis...
a weak cold front will cross the region late tonight and Thursday
morning...and may bring a light shower or two to the area. Following
the front...Canadian high pressure and a reinforcing shot of
noticeably cooler air will briefly overspread our area Thursday and
Thursday night...before a moderating trend sets in for Friday and
Saturday. The next more widespread chance of rain will arrive for
the second half of the weekend...when a complex frontal system is
forecast to cross our region.

&&

Near term /through Thursday/...
visible satellite imagery early this evening showing that just about
all of the diurnal cumulus across the region has dissipated as daytime
heating wanes...leaving mainly clear to partly cloudy skies across
western and central New York. Middle and high clouds are now working
into northern portions of New York state in advance of a weak cold
front slowly pressing in our direction from Ontario/Quebec provinces.

Low pressure will move across southern Quebec tonight. A weak cold
front trailing the low will slowly sag from southern Ontario/Quebec
across Lake Ontario and north central New York late tonight...with
this feature pushing just south of a Buffalo-Rochester-Syracuse axis
by 12z Thursday. With the boundary appearing anafrontal in
nature...any noticeable increase in cloud cover should remain
confined to areas along and north of the boundary...while areas
further south remain mainly clear to partly cloudy.

Given the lack of significant upper level support and the bulk of
any moisture remain confined to the lowest 5-10 kft of the
atmosphere...precipitation chances attendant to the encroaching front still
appear to be fairly minimal tonight and tomorrow morning. That
said...a few light showers still appear possible across the north
country/Saint Lawrence valley overnight...and across western New
York tomorrow morning along and just behind the front as it sags
southward. In fact...no more than a few sprinkles may be seen across
western New York. Lows will range from the lower 40s across
the higher terrain...to the upper 40s along the Lake Shores.

The aforementioned cold front will push south of the County Warning Area by late
morning Thursday...leaving cloudy and cool conditions across the
area in its wake. Aside from a few light showers or sprinkles as
mentioned above...the main effects will be abundant lake enhanced
cloudiness across much of the forecast area behind the front as
cool...moist air pushes across Lake Ontario. The exception will be
across the north country which will escape the lake influences and
have greater exposure to the cool dry air flowing south out of
Canada. The combination of cold advection and abundant cloud cover
will keep temperatures in the 50s across much of the area on
Thursday.

&&

Short term /Thursday night through Saturday night/...
the large area of Arctic high pressure will build overhead Thursday
night before exiting the area Friday. This will bring the potential
for frost/freeze conditions as clouds dissipate...winds lighten and
dewpoints lower. This will be the case for much of the area except
for immediate Lakeshore areas closer to the warmer lakes and the
possibility for some lake induced clouds. The coldest readings will
be found across the north country which will be in closest proximity
to the coldest and driest air across Quebec. The readings here are
likely to drop below freezing inland from the lakes and a freeze
watch will remain in effect for late Thursday night and early Friday
morning.

After a cold start Friday morning...temperatures will moderate as
the high moves off to the east. The combination of abundant sunshine
and increasing warm advection on the back side of the departing high
will push temperatures back into the lower to middle 60s.

The high will continue to move off to the southeast Friday night and
Saturday. A warm front will push through the region during Saturday
and help to boost temperatures to near summertime levels with most
highs in the lower to middle 70s...with a few reading near 80 possible
in favored downslope areas. Southwest winds will pickup as he
pressure gradient tightens between the high to the southeast and the
approach of a surface cold front from the northern Great Lakes. It
should be a breezy day with gusts to near 35 miles per hour downwind of the
lakes.

A wave of low pressure develops along southward sagging cold front
Saturday...with a consensus track just north of the state during the
day. The deeper moisture and elevated instability plume will
gradually shift south with time. We should start to see band of
showers spread into the area Saturday night. There is some potential
for the leading edge of precipitation to reach northern portions of
the area late Saturday afternoon.

&&

Long term /Sunday through Wednesday/...
as the upper level trough works into the Great Lakes Sunday...a
surface low pressure is expected to develop in the northern Great
Lakes. A cold front will extend south from this feature...moving
through the state during the day Sunday. A period of showers and
possibly a few thunderstorms will accompany the front as it moves
through...as there is a suggestion of tropical moisture for the
southwest Continental U.S. Advecting northeast into the Ohio Valley and Great
Lakes along this boundary. The upper level trough will amplify over
the region Monday and Tuesday. This will keep a cool moist cyclonic
flow regime steady state over the region with the potential of lake
enhanced/instability clouds and precipitation.

There should be improvement by middle week as the upper trough moves
out and Canadian high pressure builds down into the region.

&&

Aviation /00z Thursday through Monday/...
VFR conditions will continue across the region through this
evening...and much of the night. Visible satellite imagery early
this evening showing that just about all of the diurnal cumulus field
across the region has dissipated as daytime heating wanes. Middle and
high clouds are now working into northern portions of New York state
in advance of a weak cold front slowly pressing in our direction
from Ontario/Quebec provinces.

Tonight...the aforementioned cold front will slowly press southward
into northern New York state...bringing lower-end VFR ceilings and the
chance of a few light showers to the north country overnight. By
very late tonight/early tomorrow morning...some of the lower VFR
ceilings will may push as far south as a kbuf-kiag-kroc line...while fog
may reduce visibility at the kjhw terminal down to the MVFR range.

The cold front front will then push south of the region late
tomorrow morning possibly bringing a few scattered light
showers/sprinkles to the western New York terminals as it moves
through. The main effects will be abundant lake enhanced
cloudiness across much of the forecast area. The exception will be
across the north country which will escape the lake influences and
have greater exposure to the cool dry air flowing south out of
Canada. A period of MVFR/low MVFR ceilings will be possible tomorrow
behind the front...especially south of Lake Ontario as
cool...moist north to northeast flow off the lake will also add in
a nice upslope component. Expect MVFR/low MVFR ceilings to hang on
through much of the day across the kbuf/kiag/kroc
terminals...before possibly scattering out toward the end of the
period. Expect MVFR ceilings to move into the kjhw terminal by early
afternoon after the cold front pushes south of the southern tier.
The exception will be across the northcountry where low VFR ceilings
may scatter out Thursday afternoon for kart.

Outlook...
Thursday night through Saturday...generally VFR...with some
localized IFR southern tier valley fog will also be possible Friday
and Saturday mornings.
Sunday...VFR/MVFR with showers becoming likely.
Monday...mainly VFR with a chance of showers.

&&

Marine...
high pressure will drift south of New York state this
evening...allowing a weak cold front to cross the lower lakes later
tonight and Thursday morning. Following this front...another area of
high pressure will build from central Ontario province to the New
England coastline Thursday through Friday.

In the immediate wake of the cold front...a brief period of moderate
northerlies will bring conditions close to Small Craft Advisory
levels across southeastern Lake Ontario from Thursday morning
through early Thursday afternoon. Otherwise...winds and waves
should remain below advisory criteria through Friday.

&&

Buf watches/warnings/advisories...
New York...freeze watch from late Thursday night through Friday morning
for nyz006>008.
Marine...none.

&&

$$

Synopsis...jm
near term...jm
short term...tma
long term...tma
aviation...jm
marine...jm

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