Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 272357

Area Forecast Discussion
National Weather Service Buffalo NY
757 PM EDT WED JUL 27 2016

A weak cold front will drop southward from Canada overnight
bringing a few stray showers and thunderstorms to the North
Country tonight and and across portions of Western New York and
the Finger Lakes region on Thursday. Chances of showers and
thunderstorms will continue into the weekend as a broad trough
temporarily settles across the Great Lakes and Northeast States.


High pressure will move off to the east as a weakening cold front
moves southward across Southern Ontario. A rather impressive line
of thunderstorms has developed along the north shores of Lake
Ontario in the convergence zone between the front and lake breeze.
The vast majority of this should fall apart before it makes it
across Lake Ontario, with perhaps a stray shower making it into
the St Lawrence valley and to the south shores of Lake Ontario
this evening.

Mostly clear skies will gradually give way to clouds with the
front which will drop from north to south this evening. This will
still leave plenty of clear skies across the Southern Tier
providing good radiational cooling tonight. This should result in
some valley fog forming after midnight. Overnight low temperatures
will settle to the lower to mid 60s inland and across higher
terrain, and to the mid to upper 60s closer to the warm lakes and
in urbanized areas.

The weak cold front will continue to move south across the region on
Thursday and should reach the Southern Finger Lakes and Southern
Tier counties by midday and the afternoon. A combination of the
front and lake breeze boundaries will provide a focus for some afternoon
convection with scattered showers and possibly a few thunderstorms.
The low chance for afternoon convection will also linger over the
Saint Lawrence Valley closer to the broad upper trough over
Quebec. High temperatures on Thursday will be in the lower to
middle 80s with some upper 80s across Central New York.


There had been some hope that parts of our area would pick up some
beneficial showers and thunderstorms during this period...but the
trend of most of the guidance packages are suggesting that such
activity may not be as widespread as earlier anticipated. In fact...
a large portion of Western New York may not pick up measurable rain
through Saturday night...with an even greater chance for dry weather
found across the North Country. Looking at the details...

A weak cold front that will gradually push south across our region
on Thursday will settle across Pennsylvania where it will stall
Thursday night and Friday. While a wave moving east along the
stalled front will help to generate some showers and thunderstorms
over the Keystone state...the track of the wave is now expected to
be further to the south. General lift associated with the
disorganized sfc low will thus be further south as well...leaving
little forcing across our forecast area. Have thus backed off on the
pops a little for sites north of the Srn Tier. In fact...high
pressure based over the the Upper Great Lakes will press far enough
across Lake Ontario to promote some clearing from the north during
the course of Friday afternoon.

The sfc high will expand across all of the Great Lakes region Friday
night...and this will help to push the wavy frontal boundary even
further south across the Mid Atlantic region. Outside of a leftover
evening shower across the Southern Tier...this will leave an
uneventful night in place for our forecast area with at least
partial clearing continuing from north to south.

On Saturday...the high will make its way across New England with
generally fair weather holding in place across our region. The
exception could come across the Srn Tier where increased moisture
within the return flow around the exiting sfc high could support a
late day shower or day for sites well south of Buffalo.


A progressive...low amplitude trough over the Great Lakes at the
start of this period will push off to the East during the start of
the new work week. This will allow scattered showers and
thunderstorms at the end of the weekend to clear out...leaving
fine...mid summer weather across the region for the Monday through
Wednesday time frame.

Temperatures during this period will once again climb to levels that
will average some 5 to 8 deg f above normal early Aug values.


VFR conditions should prevail this evening. A weak outflow
boundary from convection near Toronto will cause a wind shift at
IAG/ROC shortly after 00z.

Expect mainly VFR conditions later tonight and Thursday. The
exception is at JHW where fog is likely to form after midnight,
resulting in variable vsby through daybreak. This should average
around 2SM, but could range wildly late tonight.

On Thursday a front will gradually drop south across the area, and
this combined with lake breeze boundaries may result in scattered
showers and possibly a thunderstorm Thursday afternoon. Coverage
should be quite spotty, and largely avoiding TAF sites.


Thursday night...Mainly VFR with a chance of showers and
Friday through Sunday...VFR/MVFR with a chance of
showers and thunderstorms.


A weak cold front will gradually drop south across Lake Ontario
overnight. This will then be followed by another high pressure
area late in the week. Winds and waves are expected to remain
below small craft criteria into the beginning of the weekend.





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