Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 281855

Area Forecast Discussion
National Weather Service Buffalo NY
255 PM EDT THU JUL 28 2016

A weak cold front will slide southward across New York State this
evening and tonight, then a wave of low pressure will move south of
the region tomorrow, bringing chances for scattered showers and
thunderstorms to the Southern Tier. Weak high pressure on Saturday
should limit shower activity to near the Pennsylvania state line.
The chances for scattered showers and thunderstorms increase again
Saturday night through Sunday night. Warm and humid conditions will
stay in place tonight, then temperatures will cool slightly but
remain above climatological averages over the weekend.


A weak cold front will continue to move southward across New York
State tonight, which may support the late day and evening
development of scattered showers and thunderstorms. Most convection
will be limited to the Southern Tier, but there may also be a
slightly lesser chance across the Saint Lawrence Valley and North
Country, closer to the 100kt+ 250mb jet aloft. There will be little
airmass change overnight as mild and humid conditions will persist,
overnight low temperatures in the lower to mid 60s inland and over
higher terrain and to the upper 60s or low 70s near the Great Lakes
and within urbanized areas.

Northerly winds set up on Friday which should bring slight cooler
and less humid air to the region. A wave of low pressure passing
eastward across Pennsylvania, on its way to becoming a coastal low
off the Mid-Atlantic states. It will bring an enhanced chance of
showers and thunderstorms to the Southern Tier on Friday, but the
rest of the forecast area should remain free of any precipitation.
High temperatures will be in the upper 70s to lower 80s, which
should feel more comfortable than it has been for the past many


A broad midlevel trough and embedded vorticity maxima is forecast to
cross from the Midwest and Great Lakes to the Mid-Atlantic and New
England regions through the weekend. This trough will trigger a
surface low somewhere from the Ohio/Tennessee River Valleys shifting
east to the Mid-Atlantic region. Sufficient synoptic moisture will
be in place ahead of the trough and low to drive some showers and
possible thunderstorms mainly south of our forecast area on Saturday
then shifting north and east across our region on Sunday.

Large differences remain between the relatively dry 12z GFS and more
moist 12z ECMWF which leave a lower than normal confidence in a
forecast at this short range. While most of Friday night should be
dry, have introduced chance POPs across the Southern Tier later
Friday night. POPs have been increased some on Saturday while edging
them a little further north to hedge at least partially toward the
wetter EC model but still preserving a majority of continuity.

Higher confidence is found on Sunday where a sharper embedded
shortwave trough and higher level of instability looks to drive a
more widespread area of showers and thunderstorms. The highest POPs
over the weekend timeframe will be in place on Sunday. By Sunday
night the trough axis will shift east of the forecast area with POPs
tapering off as high pressure and mid-level ridging arrive from the
west. Temperatures over the weekend will be cooler than recent days
but still averaging a touch above mid-summer normals. Easterly winds
should prevent cooler temperatures from occuring on the eastern
shores of Lake Erie due to some downsloping.


A progressive low amplitude pattern will remain in place along the
Canadian border through early next week with dominant ridging
remaining in place from the central Plains to the southeast states.

High pressure will build into the Great Lakes region Monday and
Tuesday with a return to dry weather. The surface high will drift to
the east coast by Wednesday and still remain close enough to keep
the next system and deeper moisture at bay, with a continuation of
dry weather.

Temperatures will start next week not far from average with highs in
the lower 80s on Monday. The heat will build again by midweek as the
surface high moves to the east coast and deep southwesterly return
flow develops. This will boost high temps into the upper 80s by


Expect mainly VFR conditions tonight and Friday. A front will
gradually drop south across the area, and this may result in
scattered showers and possibly a thunderstorm this evening.
Coverage should be quite spotty, and largely avoiding TAF sites.

The front will be south of the region on Friday and as a wave of low
pressure passes the area to the south, there may be scattered
showers and thunderstorms across the Southern Tier but it should be
far enough to the east to avoid KJHW.


Tonight...Mainly VFR with a chance of showers and thunderstorms.
Friday through Sunday...VFR/MVFR with a chance of showers and
Monday and Tuesday...VFR.


Weak flow today will keep mainly lake breeze dominated winds and
minimal waves on the lakes through this evening. Then, a wave of low
pressure will track from central Pennsylania to east central New
York State supporting a freshening northeasterly wind, especially on
eastern Lake Ontario where wind speeds may approach small craft
criteria toward Friday morning. This will bear watching in later
forecasts. Otherwise high pressure will build in across the lower
Great Lakes later Friday and into Saturday resulting in diminishing
winds and waves.





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