Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 280853

Area Forecast Discussion
National Weather Service Buffalo NY
453 AM EDT Fri Jul 28 2017

Notably less humid conditions will be in place for the next several
days as expansive high pressure will build across the Great Lakes.
While western and north-central New York will be able to enjoy fine
weather through the weekend, an unusually well organized mid summer
storm system will dump excessive rains over parts of Pennsylvania
and the mid Atlantic region.


High pressure is centered over northern Lake Superior this morning.
This feature will allow for mainly dry weather through the remainder
of today and tonight. Satellite and surface obs show some lingering
low clouds and patchy fog mainly from the Finger Lakes into central
NY while some thin broken high level clouds are also drifting across
the central and easter Great Lakes. Temperatures will remain very
mild as dewpoints are still in the low to mid 60s despite
northeasterly flow.

After sunrise, a steady Northeast flow will develop over western and
central New York which will begin to bring in some relatively cooler
air over our region. Cold air advection will lower 850mb temps to
between 10C and 12C which will limit high temps today at the surface
to the lower 70s. Dewpoints will also begin to lower through the
afternoon making for more comfortable humidity levels. While skies
will be mostly sunny across the North Country, mostly cloudy
conditions will be more prevalent south of Lake Ontario. This will
be particularly so across the Southern Tier where low level moisture
from a passing Mid Atlantic storm system will become trapped under
the expanding high pressure ridging. There is a chance of a few
showers in the western Southern Tier where the HRRR is most
aggressive with trying to sneak some precipitation north of the PA

Tonight, our region will remain between the the center of high
pressure over the Michigan UP and a strengthening coastal storm
moving off the Delmarva. This will keep a northeast flow steady
through the night while skies become more clear across upstate NY
with the depart of the coastal storm. No precipitation is expected
and the steady winds should prevent much of any fog development. A
drier airmass will allow for a cool night with temps dipping into
the 50s.


It is shaping up to be a beautiful weekend across western and north-
central New York as upper level ridging will be building into the
region on the backside of a filling cutoff low that will be slowly
making its way off the mid-Atlantic coast. Cirrus associated with
this feature will cloud skies to start the day on Saturday, but this
should slide off to the southeast through the morning, with
widespread sunshine expected by the afternoon. Fair skies will
persist throughout the rest of the weekend, as upper level ridging
and associated surface high pressure will remain in place across the
Great Lakes.

The fair skies will be complimented by pleasant temperatures
throughout the weekend, as a seasonably mild airmass will be in
place across the region, with generally light northerly flow
prevailing. Highs will run in the 70s during the days, with 50s at
night, and dewpoints will remain in the 50s, as dry air to our north
is advected into the area, making it feel quite comfortable outside.

The ridging will remain over the forecast area at least through
Monday, resulting in what should be at least one more pleasant day
across the region. Temperatures will begin to warm as the upper
level ridge crests the region, and highs on Monday will creep back
above the 80 degree mark across portions of the forecast area, with
lows falling into the low to mid 60s across most areas, with the
exception of the cooler spots of the Southern Tier, where upper 50s
are expected.


After a quiet weekend and start to the week, things will gradually
become more unsettled across the region, as the upper level ridging
over the lower Great Lakes is replaced once again by troughing. An
initial weak shortwave crossing the area may aid in bringing a few
diurnal/lake-breeze driven showers Tuesday afternoon, with another
round of showers possible Wednesday afternoon as heights begin to
fall ahead of a more substantial upper level trough over the upper
Great Lakes. Thursday currently appears to be the most promising day
for widespread rainfall of the period, as a slow-moving cold front
is forecast to advance across the region as a deep upper level
trough digs across the Great Lakes.

We should see a gradual warm-up through the middle of the coming
week, as a return flow around high pressure over the Southeast
begins to advect warmer and more moist air into the Great Lakes.
Temperatures will return to the 80s in both Tuesday and Wednesday
afternoon, and dewpoints returning to the 60s will bring mugginess
back into the air. Thursday may run a little cooler, in the mid to
upper 70s, pending the anticipated widespread precipitation. The more
humid airmass eluded to above will result in warmer nights, with
lows in the low to mid 60s.


High pressure over Lake Superior will allow for mainly dry weather
today and tonight along with VFR cig/vis. The position of the high
will also bring a steady northeasterly flow through tonight. While
some patchy fog has developed in the Finger Lakes this morning
(KELZ/KDSV), a steady northeast flow should keep KJHW in VFR. There
may be a few isolated showers that try to sneak into the western
Southern Tier of NY today but confidence is too low to include in
KJHW TAF at this time. Any low/mid clouds around today will become
mainly thin high clouds tonight with some clearing occuring late
from north to south. No fog expected tonight was winds will remain
steady from the northeast overnight.


Saturday through Monday...VFR with only the chance for late night
IFR/MVFR vsbys across the Southern Tier.
Tuesday...Mainly VFR. A slight chance of showers and thunderstorms.


Northeasterly flow has set up over the eastern Great Lakes as an
area of high pressure has centered over Lake Superior. The NE flow
will remain at this direction through Saturday morning. These winds
will increase to 15-20 knots Friday morning and again Friday night,
while producing waves of 2 to 4 feet for the Lake Ontario nearshore
waters west of Sodus Bay. This has allowed small craft advisories
to be issued.

Winds appear to have enough of an easterly component near the
Niagara River such that a SCA will not be needed.

On Lake Erie...winds will yield the highest waves on the western
waters of the lake...with waves 3-5 feet from Ripley to Dunkirk
where a new Advisory has been issued.

Otherwise, high pressure over the eastern Great Lakes will bring
fine boating conditions continuing through the weekend.


A storm system developing over the Middle Atlantic states
today into Saturday will combine with high pressure over the
Upper Great Lakes to produce some elevated northeasterlies on
Lake Ontario. Recent model guidance has backed off on the
strength of the northeast winds, now only 15-20 knots, such
that the risk for additional significant erosion and flooding
along the south shore of the lake is now reduced. Have cancelled
the lakeshore flood watch for Niagara county to Wayne county
with waves only expected to reach 2-4 feet.


MARINE...Small Craft Advisory from 2 PM this afternoon to 2 AM EDT
         Saturday for LEZ040.
         Small Craft Advisory until 6 PM EDT Saturday for



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