Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 252340

Area Forecast Discussion
National Weather Service Buffalo NY
740 PM EDT MON JUL 25 2016

Any isolated showers and thunderstorms over the western Finger Lakes
will end this evening as a cold front crosses the region, with
clearing skies overnight. This front will usher in another period of
fair and slightly less humid weather that will persist through
midweek. Another, much weaker cold front will slide south out of
Canada Wednesday night into Thursday, bringing a slight chance of
showers and thunderstorms, but nothing that is expected to put a
dent in the current drought conditions.


The isolated convection that developed late this afternoon along the
strong boundary intersection between the Lake Erie breeze and the
Lake Ontario breeze has since moved off the boundary, and is
weakening across portions of Wyoming and Livingston counties.
Another lone shower along the Wayne county shore will move east
through early evening. All of this activity will dissipate by around
9pm as the boundary layer stabilizes and low level convergence is

Steady albeit weak cold advection behind the front will eventually
allow for somewhat cooler air to work into the area overnight, with
lows in 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 earlier today may allow for some river valley fog across
the Southern Tier overnight and early Tuesday morning. For the rest
of the area, enough gradient wind should continue overnight to
prevent fog formation.

The upper level trough will complete its transition across the
forecast area overnight 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
Tuesday 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


There should not be much weather to contend with during this 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 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 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 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.


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.


Isolated thunderstorms which formed during the late afternoon along
the strong boundary intersection between the Lake Erie and Lake
Ontario lake breezes across the Niagara Frontier are now weakening
and moving into the western Finger Lakes. These remaining storms
will dissipate by 02Z. An area of MVFR CIGS east of Lake Ontario
will also dissipate by around 02Z as drier air begins to move into
the area. Otherwise the rest of the area will see clearing skies
this evening as a cold front pushes east of the area, with VFR

Overnight expect VFR in most areas, with some patchy valley fog in
the Southern Tier producing local IFR. It appears that enough wind
will remain just off the deck overnight to prevent fog from forming
at KJHW. Any valley fog will burn off early Tuesday morning. VFR
will then prevail across the entire region with some diurnal cumulus
developing by midday along and inland from the lake breeze
boundaries, especially east of Lake Ontario where somewhat deeper
moisture will be found.


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


Gusty southwest winds will continue to be an issue this evening on
Lake Erie as a cold front crosses the region, and small craft
advisories remain in effect. Winds will diminish rapidly behind the
cold front later this evening on Lake Erie, however westerly flow to
around 15 knots on Lake Ontario will generate moderate chop on the
eastern end of the lake 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.


NY...Beach Hazards Statement until 11 PM EDT this evening for
MARINE...Small Craft Advisory until 11 PM EDT this evening for LEZ020-



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