Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 260510
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
110 AM EDT TUE JUL 26 2016

.SYNOPSIS...
High pressure will track from the Central Great Lakes to the Eastern
Great Lakes today, bringing abundant sunshine, and summer`s heat in
the 80s. Dry weather will persist until a weak cold front drops
southward from Canada Wednesday night bringing a few stray showers
and thunderstorms to the region Wednesday night and Thursday.

&&

.NEAR TERM /THROUGH TODAY/...
Mainly clear skies this early morning, combined with somewhat cooler
air behind the surface cold front will allow for temperatures to
drop into the mid 60s on the lake plains and lower 60s in the
Southern Tier valleys and Lewis County. Radiational cooling combined
with the rain from yesterday may allow for some river valley fog
across the Southern Tier early this morning. For the rest of the
area, enough gradient wind should continue this early
morning to prevent fog formation.

The upper level trough will complete its transition across the
forecast area and will be replaced by low-amplitude upper level
ridging and surface high pressure across the Lower Great Lakes. This
should yield plenty of sunshine across most of the area today with
just some modest diurnal cumulus development along and inland from
the lake breeze boundaries. East of Lake Ontario cumulus may become
a little more widespread with model guidance suggesting a more
robust layer of moisture near 850mb. Highs will be in the low to mid
80s, with 70s along the lakeshores from local onshore flow.
Slightly lower dewpoints in the upper 50s to lower 60s advecting in
behind the front will make it feel nominally more comfortable
outside.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
There should not be much weather to contend with during this
period...as a low amplitude flow will be found along the length of
the Canadian border. While troughiness will characterize this
pattern over the Great Lakes region...a lack of baroclinicity and
low level forcing will mean that generally fair weather can be
anticipated. This despite the passage of a weak cold frontal
boundary. The day to day details...

High pressure centered over the Mid West will remain in control
across our forecast area Tuesday night. While light winds and clear
skies will encourage decent radiational cooling...we have not had a
fresh airmass change in a few days...so the mercury is only forecast
to drop into the mid 60s across the lake plains while 50s will be
found across much of the Srn Tier.

A cold frontal boundary over the Upper Great Lakes will then slowly
push south across Southern Ontario during the day Wednesday...while
high pressure over the Mid West will gradually lose control of our
weather in the process. Nevertheless...fair weather will persist
across the region with H85 temps in the upper teens C supporting
afternoon readings in the upper 80s to near 90 for the lake plains
and in the valleys.

We can anticipate a weak frontal passage Wednesday night...but with
little forcing...will only raise pops to slgt chc while increasing
cloud cover. Temperatures overnight will be a few degrees higher
than the night before...but with dew points holding steady near
60...it should not be overly uncomfortable.

The frontal boundary will stall and wash out over Pennsylvania on
Thursday...while a ribbon of moisture in its wake will settle over
our forecast area. The bulk...if not all...of the day will be rain
free...but the passage of a shortwave in the northwest flow will be
enough to warrant low chc pops for the afternoon and evening. Since
a northeast low level flow will be in place in the wake of the
front with little instability...will only use a slgt chc for tstorms.

The various guidance packages remain out of step with each other as
we push into Thursday night...as there is a `disagreement` as to
whether a wave will form along the west end of the aforementioned
frontal boundary. Will keep low chc pops in place for all but the
North Country. While there will be low confidence with these pops...
there is more certainty that clouds will remain in place...
especially over the western counties.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
This period has the potential to be rather unsettled...or at least
more disorderly than what we have become accustomed to the past
couple months. The good news is that this would lead to some needed
rainfall for the region...but the bad news is that it would
adversely impact some peoples plans for the weekend.

Troughiness found over the Great Lakes region is forecast by some of
the ECMWF/GFS based ensembles to amplify somewhat...and this would
encourage waviness along a stalled frontal boundary over the Mid
West to evolve into an actual sfc low. Will use a compromise of the
HPC and ECMWF solutions...which favors such a sfc low development.
This feature is forecast to slowly track northeast across the Lower
Great Lakes during the course of the weekend while generating
scattered showers and possible thunderstorms in the process. Given
the low confidence of this forecast...will keep chc pops in place.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
VFR flight conditions are found at 06Z across the TAF region, and
these conditions will be predominate through Tuesday night. The
exception will be across the Southern Tier river valleys where
radiational cooling over a wet ground will allow for patchy areas of
fog to form, possibly nearing the KJHW terminal. For now it appears
that there will be enough of a gradient wind to maintain the lower
VSBYS within such fog just to south and east of the airport this
morning.

Expect light winds through the TAF cycle with surface high pressure
nearing the region from the Central Great Lakes.

VFR flight conditions will persist into tomorrow night, with again
just the possibility of Southern Tier Valley fog formation, that may
again being lower flight conditions to near the KJHW airport.

Outlook...

Tuesday Night and Wednesday...Mainly VFR.
Thursday...Mainly VFR with a chance of showers and thunderstorms.
Friday and Saturday...VFR/MVFR with a chance of showers and
thunderstorms.

&&

.MARINE...
Winds will continue to diminish overnight on Lake Erie with waves
subsiding. Westerly flow to around 15 knots will persist on Lake
Ontario and generate moderate chop on the eastern half of the lake
later tonight and Tuesday, though conditions should remain just
below small craft advisory levels. After that, high pressure will
build across the Lower Great Lakes, with winds and waves remaining
generally tranquil through the remainder of the week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...HITCHCOCK/THOMAS/WOOD
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...THOMAS
MARINE...HITCHCOCK/WOOD


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