Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 261048

Area Forecast Discussion
National Weather Service Buffalo NY
648 AM EDT Sat May 26 2018

Persistent southwesterly flow will continue to bring very warm
weather through the Memorial Day holiday. There will be a few widely
scattered showers and thunderstorms each day, mainly across the
North Country and areas well inland from the lakes. Even in these
areas, the vast majority of the time will be rain free.


IR satellite imagery shows most of the thicker clouds confined to
areas over and east of Lake Ontario early this morning, with thin
high clouds for the rest of the area. Thicker high/mid level clouds
upstream across southwest Ontario and Michigan will overspread the
area later this morning. A few widely scattered showers will
continue in the Saint Lawrence Valley through this morning.

High pressure will remain anchored off the coast of the southeast
states today and tonight, with persistent southwesterly flow across
the Ohio Valley and eastern Great Lakes. A shrinking bubble of drier
air will persist over our region today, keeping most areas dry. The
presence of this dry air, combined with warm mid level temperatures
will keep instability anemic for the bulk of the area, with SBCAPE
only around 500J/kg despite the very warm surface temperatures. An
isolated shower cannot be ruled out late this afternoon across the
higher terrain of the western Southern Tier near the PA state line,
but otherwise the bulk of Western NY and areas southeast of Lake
Ontario will be rain free. Mid/high clouds will increase across the
area today, yielding partly sunny skies.

The one exception to the dry weather will be across the North
Country. A stalled frontal zone will remain draped from the Ottawa
Valley to northern NY and act as a conduit for several mid level
waves to move along. Instability will also be greater in this area
with better boundary layer moisture and cooler temperatures aloft.
These waves will produce a few periods of scattered showers today
and tonight, with the better coverage of showers and scattered
thunderstorms expected this afternoon and evening with increased
diurnal instability. Southwest flow off Lake Ontario will maintain a
stable lake shadow for most of the eastern Lake Ontario region, with
shower chances mainly relegated to the Thousand Islands region and
western foothills of the Adirondacks on the fringe of the stable
lake shadow.

Most of the showers and scattered thunderstorms across the North
Country will end later this evening with the loss of diurnal
instability, although a few more widely scattered showers cannot be
ruled out overnight. A few scattered showers may also develop
overnight across the western Southern Tier, and eventually the
western Finger Lakes toward Sunday morning as a weak mid level wave
and deeper moisture cross PA and the Southern Tier of NY.

Temperatures will continue to be very summer-like, with highs in the
mid 80s today at lower elevations in Western NY, and upper 70s for
the North Country. A southwest breeze will keep the Buffalo and
Watertown areas cooler. Lows tonight will be in the lower 60s for
most, with some upper 50s in the cooler Southern Tier valleys and
Lewis County.


Summery warmth and humidity will continue through the second half
of the holiday weekend, with scattered afternoon shower and
thunderstorm chances inland from the lakes.

A diffuse shortwave will cross NYS on Sunday, which will help
trigger some widely scattered showers and thunderstorms developing
along a convergent boundary near the Genesee Valley and along the
Lake Erie lake breeze boundary over the western Southern Tier. Dew
points will continue to rise to into the mid 60s, helping to fuel
some instability for convective initiation as well as making for a
more uncomfortablely humid feel to the air. Temperatures will be in
the mid 80s inland from the lake breezes, with cooler readings in
the 70s along the lake shores. Light northeast winds south of Lake
Ontario near the convergent boundary will actually help Buffalo one
of the warmer spots, with the south shore of Lake Ontario and
Rochester area slightly cooler.

Any showers and thunderstorms will move into Central NY by Sunday
evening, however activity that forms across the Ontario peninsula
Sunday will venture eastward across Lake Erie and Lake Ontario.
Expect this will largely be diminishing by the time it reaches the
forecast area, and have decreased overnight PoPs into the slight
chance range. Temperatures will stay mild overnight with
temperatures in the mid 60s.

Memorial Day will be warm with the potential for temperatures to
reach the mid-upper 80s in interior valleys. Dewpoints will continue
to hover in the mid to upper 60s making for a slightly uncomfortable
day. An upper level trough axis will move across the region during
the day and winds will become northerly by Monday evening. Shower
and thunderstorm chances will be mainly confined to interior areas
of the forecast area and over the higher terrain in closer proximity
to a front that should be to the south. Locations along the lake
plains will be both shadowed by the lake breezes and away from the
better moisture and forcing behind the front. Activity will taper
off into Monday evening with mostly dry conditions expected
overnight. Lows will be in the upper 50s to mid 60s again Monday


Canadian high pressure will build across the northeast CONUS
Tuesday. This will bring a return to dry weather, as well as
give us a brief break from the heat and humidity of the holiday
weekend, with highs in the mid 70s to around 80 and dew points back
into the 50s.

The high will start to drift east Wednesday bringing back some
warmer and more humid air. The day should remain dry, but can`t
completely rule out an isolated afternoon shower or storm near the
Lake Erie Lake Breeze given the returning instability.

As we head into Thursday and Friday, the upper level ridge will be
ushered off to the east, while a potent shortwave approaches from
the northern Plains and the remnants of Alberto push into the Ohio
Valley. This will bring a better chance for scattered showers and
storms for Thursday and Friday, as well as the potential for locally
heavy rainfall.


VFR will prevail today and tonight with a bubble of relatively drier
air holding strong over the eastern Great Lakes. A few showers and
thunderstorms will develop across the North Country at times near a
stalled frontal zone, with the greatest concentration of activity
this afternoon and evening mainly north and east of KART. A few
isolated showers are also possible late today and tonight across the
western Southern Tier. Otherwise the rest of the area will remain
dry with an increase in mid/high clouds.


Sunday and Monday...Mainly VFR with widely scattered showers and
Tuesday and Wednesday...VFR.


High pressure will remain anchored off the coast of the southeast
states through Memorial Day, with a weak pressure gradient in place
across the eastern Great Lakes. This will promote light winds and
flat wave action the majority of the time. High resolution guidance
suggests a brief period of moderate northeast winds may develop this
evening on Lake Ontario as a weak backdoor front and composite
outflow boundary drops southwest across the lake. If this
materializes, it would produce a few hours of choppy wave action
along the south shore of Lake Ontario starting this evening.

There may be a few widely scattered thunderstorms at times with
locally higher winds and waves.





NEAR TERM...Hitchcock
LONG TERM...Church
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