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Area forecast discussion 
National Weather Service Buffalo New York
754 PM EDT Wednesday Sep 2 2015

a weak trough will cross the region tonight and Thursday producing a
few isolated showers and thunderstorms...but the vast majority of
the area will remain dry. High pressure returns for Friday with a
return to sunshine and very warm temperatures which will last
through the entire Labor Day weekend.


Near term /through Thursday/...
through early evening...radar shows scattered showers and
thunderstorms north of Lake Ontario...but none remaining in our
County Warning Area. This will leave mainly dry conditions through the remainder
of the evening and most of the night. Late tonight a weak low
level trough will drop south out of Ontario. As this feature
crosses the warm waters of Lake Ontario...the added boost of lake
moisture and instability may be enough to produce a few widely
scattered showers or thunderstorms along the South Shore of Lake
Ontario late tonight and Thursday morning. The 12z guidance has
backed off from this solution somewhat but the hrrr does have it.
Past experience has shown that even weak boundaries can produce
scattered convection over the warm lakes during the overnight and
morning hours.

Otherwise expect more fog to develop tonight and Thursday morning
with the abundant low level moisture and longer September nights.
Most of the fog will be on the light side...but more dense fog will
form once again in the southern tier river valleys. May also see
advection fog develop over and northeast of lakes Erie and
Ontario...possibly affecting the Buffalo area and Jefferson County
shoreline. Temperatures will remain warm with lows in the upper 60s
on the lake plains and lower 60s in the coolest southern tier
valleys and Tug Hill region.

By Thursday afternoon the weak trough will be pushing south into the
southern tier and northern PA. Moderate afternoon instability
combined with weak convergence along the trough and upslope flow may
produce a few widely scattered showers and thunderstorms across the
higher terrain south of the New York state thruway. Given warm middle level temperatures
and weak forcing coverage of this activity should remain sparse. The
lake plains from the Lake Erie shore to the Niagara Frontier and
Rochester should see increasing amounts of sunshine during the
afternoon as northwest flow spreads stable lake shadows inland.

It will be another warm day with highs in the middle 80s across lower
elevations and lower 80s on the hills. The developing northwest flow
will keep the lakeshores a little cooler. Dewpoints will remain in
the 65-70 degree range making for another humid day.


Short term /Thursday night through Friday night/...
warm and dry late Summer weather will continue. A weak upper low
stalled underneath a longwave ridge is forecast to stall across
Michigan while ridging strengthens across New England. Meanwhile...a
surface high will drop southward from Canada and advect slightly
cooler and drier air into the region. Temperatures will remain above
normal with highs averaging in the lower 80s on Friday.

Dew points will also drop into the lower 60s to upper 50s which will
make it feel less humid. This will result in cooler overnight lows
which should drop to near these dew point values on Thursday and
Friday nights. Fog should form each night...but the drier air mass
should result in less widespread fog in the more typical valley
locations and maybe along the lake plains south of Lake Ontario.


Long term /Saturday through Wednesday/...
the Holiday weekend will be warm and sunny as the axis of the upper
level ridge shifts across the Great Lakes with strong surface high
pressure dominating at the surface. Highs will run in the middle 80s
Saturday and Sunday with the warmest temperatures of the period
falling on Monday as the center of the high shifts to the Middle-
Atlantic States and southwesterly flow returns to the lower Great turn advecting warmer air out of the Ohio Valley and
generating downsloping that will push temperatures on Labor Day into
the middle to upper 80s across the Genesee Valley and north of The
Finger lakes with middle 80s elsewhere. Lows through the period will
continue to run in the 60s.

12z GFS/ECMWF/ggem guidance are in excellent agreement through
Monday and although this agreement breaks down a bit toward middle-week
the individual solutions are still fairly close. Consensus has a
weak cold front approaching Monday night with this likely to drop
across or into our region on Tuesday before stalling out Tuesday
night. Then a shortwave will lift this boundary back toward the
region with an increasing chance for thunderstorms on Wednesday.
Despite the cold front...temperatures should remain above normal
through mid-week.


Aviation /00z Thursday through Monday/...

For the 00z taf cycle...diurnally driven cumulus have scattered
out leaving VFR conditions in most locations. Some fog and low
stratus may form again this evening over Lake Erie and Ontario...
but with light flow this should primarily remain over and along
the lakeshores with little impact on the terminals. By late
evening patchy fog/br will begin to form across land areas with
MVFR/IFR visibility developing. Fog will become most widespread across
the southern tier river valleys overnight with LIFR visibility.
Visibility/ceilings are also likely to drop to IFR at Art with a weak
surface trough which will move through late tonight and Thursday

On Thursday an isolated shower or thunderstorm may develop along the
South Shore of Lake Ontario during the morning hours as a weak
trough combines with lake moisture. The fog/br will continue to
produce areas of MVFR/IFR visibility through middle to late morning before
mixing out. By afternoon any isolated showers or thunderstorms will
focus across the higher terrain to the south of the thruway...but
again coverage is expected to remain sparse.

Friday through Monday...VFR. Localized IFR in overnight/early
morning fog.


a weak trough will cross the lower lakes on Thursday. In the wake of
this trough northeast winds will increase to around 15 knots
Thursday night and Friday on both lakes. This will produce some
choppy wave action...but conditions are expected to remain below
Small Craft Advisory criteria.

High pressure will then build along the East Coast over the Labor
Day Holiday weekend and provide light winds and flat wave action
Saturday through Monday.


Buf watches/warnings/advisories...
New York...none.



near term...apffel/Hitchcock
short term...apffel
long term...apffel

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