Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 231431

Area Forecast Discussion
National Weather Service Buffalo NY
1031 AM EDT SAT JUL 23 2016

Hot and humid conditions will last through the weekend as high
pressure moves across the Lower Great Lakes. Outside of some showers
and thunderstorms across the North Country and Saint Lawrence
Valley today...conditions will be largely rain free. A cool front
will then bring at least a chance of showers and thunderstorms
Monday as it crosses our region...then dry weather and above-
average temperatures return to the area for much of next week.


For the mid-morning update, only minor tweaks are needed as high
pressure continues to result in a fine summer day for virtually all
of Western and North-Central New York, though perhaps that is cold
comfort for those hoping for a break in the drought conditions
plaguing the region. A weak frontal boundary that dropped south
across Lake Ontario overnight has ushered in somewhat drier air into
the region, resulting in slightly more comfortable conditions,
particularly across Western NY. The abundant sunshine will push
temperatures back into the upper 80s this afternoon, with a few
spots in the Genesee Valley and Lake Ontario plain cracking 90
degrees, though lake breezes should yield cooler conditions near the
lakeshores of both Erie and Ontario.

The one notable exception to the quiet day will be the St. Lawrence
Valley and North Country. After a sunny start to the day, we should
see an increase in cloud cover, along with the development of
scattered showers and thunderstorms this afternoon as a shortwave,
prominent on WV imagery this morning, drops across the St. Lawrence
Valley. The stabilizing effect of the lake breeze should keep
convection limited to inland areas of Jefferson county and into
Lewis county this afternoon.  Timing in the grids has been adjusted
slightly to account for the slightly slower progression of the wave
on WV imagery, vs. earlier model guidance.

Tonight high pressure will expand across the entire cwa with fair
weather and mainly clear skies. The drier air mass combined with
favorable radiational cooling should allow temperatures to cool
quite nicely, probably a bit cooler than consensus guidance. Lows
should range from the mid and upper 50s across the interior valleys
to the mid 60s across the lake plains.


Summer`s heat and humidity will remain with us through Monday as
upper level ridge of high pressure remains over the Eastern U.S. A
zonal flow will dominate the U.S. Sunday and Monday, with a fast
moving shortwave advancing eastward along the US and Canadian
border. This shortwave, currently near Montana and southern Alberta
Province Canada will reach WNY later Sunday night, and may trigger a
few showers and thunderstorms late Sunday night and Monday.

First, for Sunday 850 hPa temperatures ranging from +18 to +22c
across the CWA will yield another hot afternoon with air
temperatures peaking in the mid 80s to lower 90s. Though dewpoints
may actually start the day at a comfortable level (in the 50s) we
will see an increase in moisture within the boundary layer through
the day which will increase these dewpoints to 60, and the lower 60s
by Sunday evening.

This increase in moisture will peak Monday ahead of a cold front
that will near us from the Upper Great Lakes. A few showers and
thunderstorms will be possible Sunday night within a layer of
elevated instability. Greatest chances for storms will be near the
lake plains and the Southern Tier. Later Monday after the initial
round of showers and thunderstorms, we will see an increase in
convection, this tied to the surface as daytime heating increases
SBCAPE values to 1000 to 1500 J/KG. This activity, while possible
across the CWA will have the highest chances inland along lake
breeze boundaries across the interior Southern Tier, Genesee Valley
and Finger Lakes region. A stiff southwest wind off Lake Erie Monday
will likely bring another dry late morning and afternoon period with
sunshine. Later Monday the cold front will cross the region,
bringing chances for additional showers and thunderstorms before
drier and slightly cooler weather reaches us Monday night and into

Highs Monday will again top out in the mid 80s to lower 90s, before
cooler air reaches us Tuesday with daytime highs in the low to mid
80s. Tuesday should be dry with high pressure expanding eastward
across the Eastern Great Lakes region.


Surface high pressure will build slowly east across the Great Lakes
region Tuesday night and Wednesday with another period of dry, sunny
weather. Despite the weak cold frontal passage on Monday, there will
be little change in airmass with just slightly less humidity, but
still above normal temperatures. Expect highs on Wednesday to reach
into the mid to upper 80s in most areas, with a few 90 degree
readings possible in the normally warmer spots of the Genesee

Thursday and Thursday night a trough will move east across Ontario
and Quebec. The stronger forcing will remain well north of the
Canadian border, with a trailing weak surface cold front moving east
across the Great Lakes. The frontal passage will provide at least
some chance for scattered showers and thunderstorms, with spotty

The latest 00Z ECMWF and GFS guidance clears the front east of the
area later Thursday night, with weak high pressure allowing dry
weather on a light northerly flow to return by next Friday.
Temperatures will be knocked back a notch to a little closer to
average behind the front by Friday.


Current forecast remains on track with only slight adjustments to
the timing of the expected convection east of KART this afternoon.
Otherwise, continue to expect widespread VFR conditions elsewhere
to persist through the forecast period as high pressure moves
across the region, with a chance of fog in the Southern Tier
valleys tonight.

Sunday night and Monday... Mainly VFR with a chance of showers
and thunderstorms and associated brief MVFR/IFR.
Tuesday and Wednesday...VFR.


While lake breezes should once again bring a light to moderate chop
to nearshore waters this afternoon, high pressure moving overhead
should keep associated winds lighter negating the need for any SCAs
or beach hazard statements.

Some scattered showers and thunderstorms will be possible across the
Saint Lawrence Valley this afternoon. Some storms may be strong,
with gusty winds and small hail.

Generally quiet conditions should persist across Lakes Erie and
Ontario Saturday night and Sunday... before a weak cold front
crosses the region on Monday and brings the next chance for showers
and thunderstorms.





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