Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 161823

Area Forecast Discussion
National Weather Service Buffalo NY
223 PM EDT Wed Aug 16 2017

High pressure passing over the region today will provide our region
with fantastic weather through the first half of Thursday. A warm
front will then stubbornly push north across our area late
Thursday and Thursday night...with increasingly widespread
showers and thunderstorms marking its progress. This will be
followed by a cold front and more thunderstorm activity on


High pressure passing just to our north will provide us with simply
outstanding weather this afternoon and evening. Nearly ideal for
outdoor activities.

As we push through tonight...the surface high will slowly drift to
our east. This will favor mainly clear starlit skies...and with
light winds...we can anticipate comfortable conditions for sleeping
with temperatures falling into the 50s. It may be a bit chilly in
some of the Southern Tier valleys...or more likely in the foothills
of the `Dacks` in Lewis County where the mercury could dip into the
40s. The only blemish on tonights weather will be some fairly
widespread fog that will develop across the Southern Tier and also
across some of the open agricultural areas. Motorists should be wary
of some of this fog if driving through the more rural areas

On Thursday...pleasant conditions during the morning will gradually
give way to increasing clouds as a warm front will approach the
region. As we make our way through the afternoon...this cloud cover
will lower and thicken from the southwest. There could even be some
showers and thunderstorms over the far western counties by the end
of the day...with the unsettled weather further blossoming after
dinnertime. will be warm with a return of more humid
conditions. Max temps will generally be in the low to mid 80s.


A warm front will continue to lift north across the region Thursday
night. The associated showers/thunderstorm have a ample supply of
moisture with PW of 1.5 to 2.0" thus locally heavy downpours are
possible. Expect a warm muggy night Thursday night with
temperatures in the mid to upper 60s.

The showers/tstms continue into Friday ahead of and along an
approaching cold front. While most of the convection not expected to
be severe, increasing shear could be just enough to allow some of
the stronger storms to produce damaging wind gusts. SPC continues to
outline much of the region in its Day 3 outlook.  Look for max temps
in the upper 70s to low 80s.

Weak surface ridging builds across the CWA in the wake of the cold
front with drying slowly taking place with lingering showers
tapering off from west to east Friday night. It will be a few
degrees cooler with lows dropping into the low to mid 60s.


On Saturday...the GFS/ECMWF are in reasonable agreement that the
surface low responsible for the unsettled conditions late in the
work week will lift northeastward across Quebec Province...while
slowly pushing its attendant weak cool front from central/eastern
New York into New England. Meanwhile the Canadian GEM exhibits a
similar pattern...though with the low/cold front substantially
further to the south and west initially. For now...have opted to
disregard this latter (and more pessimistic) solution as it appears
to be an outlier...and instead indicate a mainly dry day for
Saturday...with just a chance of showers lingering across our far
eastern zones associated with the slowly departing cool front.
Otherwise we can expect less humid conditions and seasonable
temperatures to prevail...with afternoon highs mostly in the mid
to upper 70s.

Moving into the latter half of the weekend...some model disagreement
also continues into Sunday as well...with the GFS considerably more
amplified and slower with the passage of the next longwave trough
axis than the other guidance...which if realized would support
another general chance of showers and thunderstorms. Meanwhile...
the GEM/ECMWF would suggest a much faster/weaker trough passage
Saturday night with high pressure and dry weather then building in
for Sunday...which is much more in line with our existing continuity.
Given all this...have elected to hold PoPs below chance levels for
Sunday...with another mainly dry forecast. Meanwhile...850 mb temps
will recover a little from Saturday...which should allow highs to
climb back into the upper 70s to lower 80s.

After that there is much better agreement that Monday will feature
surface high pressure situated squarely over our region...which
should translate into a dry day and near ideal sky conditions for
viewing of the solar eclipse...while continued slow warming of our
airmass supports afternoon highs mostly in the lower to mid 80s. The
GFS/ECMWF then remain in lockstep agreement that fair and dry
weather should then continue through Monday night...before the next
mid-level trough and attendant cold front arrive on Tuesday along
with the next general chance for some showers and thunderstorms.
With warmer and more humid air advecting into our region out ahead
of this system...expect highs on Tuesday to surge into the mid to
upper 80s...while dewpoints climb back to moderately humid levels in
the lower to mid 60s.


High pressure passing over the region this evening will keep fair
VFR conditions in place for the bulk of the region through tonight.
The exception will be across the Southern Tier...where widespread
valley fog is once again expected between 08 and 13z.

While VFR conditions will be in place across the region on
Thursday...increasing clouds will lower and thicken form the
southwest during the course of the day. In fact...these clouds will
yield some showers and possible thunderstorms over the far western
counties after 18z.

Thursday night...VFR deteriorating to IFR/MVFR in increasing
coverage of showers and thunderstorms.
Friday...MVFR improving to VFR with showers and thunderstorms
exiting during the midday and afternoon.
Mainly VFR with a chance of showers and thunderstorms.
Saturday into Monday...Mainly VFR.


High pressure drifting across the Lower Great Lakes tonight will
keep light winds and minimal waves in place through the first half

As the high pressure exits across New England...a warm front will
approach the region Thursday afternoon. This will set up a light
southeasterly flow with negligible waves remaining in place.

Showers and thunderstorms associated with the warm front will
increase in coverage later Thursday afternoon and particularly
Thursday night. Mariners should be wary of the deteriorating some of the thunderstorms may warrant special marine

The showers and thunderstorms will persist across the Lower Great
Lakes through at least the first half of Friday when a cold front
will push across the region. These storms could again be rather
strong...especially on the eastern half of Lake Ontario and in the
St Lawrence Valley.





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