Area Forecast Discussion
Issued by NWS Buffalo, NY

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711
FXUS61 KBUF 280623
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
223 AM EDT Fri Jul 28 2017

.SYNOPSIS...
Notably less humid conditions will be in place for the next several
days as expansive high pressure will build across the Upper Great
Lakes. While western and north-central New York will be able to
enjoy fine weather through the weekend, an unusually well organized
mid summer storm system will dump excessive rains over parts of
Pennsylvania and the mid Atlantic region.

&&

.NEAR TERM /THROUGH TODAY/...
High pressure is centered over northern Lake Superior early this
morning. This feature will allow for dry weather through the
remainder of today and tonight. Lingering clouds and patchy Southern
Tier river valley fog will be found this morning behind a cold front
which has now passed to our south. Temperatures will remain very
mild as dewpoints are still in the low to mid 60s despite
northeasterly flow.

After sunrise, Northeast flow over western and central New York will
begin to bring in relatively cool air over our region so that most
areas will only experience afternoon temperatures in the lower 70s.
Dewpoints will also begin to lower with the influx of the cooler and
drier northeasterly flow, speaking of which will bring a steady flow
of 10-15 mph this afternoon. While skies will be mostly sunny across
the North Country, clouds will become more prevalent south of Lake
Ontario and particularly across the Southern Tier where low level
moisture from the Mid Atlantic storm system will become trapped
under a fairly strong subsidence inversion.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
An upper level trough near Northern MN should have closed off and be
somewhere near Eastern OH/Western PA Friday Night into Saturday.
This scenario paints a rather dreary picture for areas south of NYS,
but results in weak subsidence overhead.  Surface high pressure
underneath a longwave ridge upstream should therefore be the
dominant feature for the weekend. The ridge will remain just
upstream, with NE flow over the region through the weekend.

The result should be dry weather for the entire region.  The only
concern would be along the PA border/Southern Tier, where some
moisture could sneak north across the border if the low ends up a
little north of most models.  Otherwise, the main impact will be
mostly opaque high cirrus over the region mainly on Saturday. Sunday
looks better for sunshine and resulting higher temperatures closer
to normal - near upper 70s to near 80, while Saturday`s highs will
be ~5F lower.  Overnight, there may be some patchy valley fog Friday
night and Saturday night, but high clouds should prevent strong
radiational cooling. Clearing skies Sunday night may result in
typical inland river valley fog.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A slow moving low over the mid-Atlantic will make its exodus along
the New England coastline through mid next week. Meanwhile, a bubble
of high pressure will build in from the upper Great Lakes keeping a
supply of seasonable and mainly dry air into the region early in the
week. By mid-week slowly increasing humidity with a weak frontal
passage from a shortwave passing to our north will spark some
scattered showers and thunderstorms. Temperatures will be mainly
seasonable through the period, although will peak on Wednesday with
highs just above normal in the low to mid 80s. Temperatures will
return to normal by Thursday behind a weak frontal passage. Lows
will be near normal in the upper 50s to mid 60s.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
High pressure over Lake Superior will allow for dry weather today
and tonight along with VFR cig/vis. The position of the high will
also bring a steady northeasterly flow through tonight. While some
Southern Tier valley fog has developed well inland from Lake Erie
this morning (KELZ), a northeast flow should keep KJHW in VFR. Any
low/mid clouds around today will become mainly thin high clouds
tonight.

Outlook...

Saturday through Monday...VFR with only the chance for late night
IFR/MVFR vsbys across the Southern Tier.
Tuesday...Mainly VFR. A slight chance of showers and thunderstorms.

&&

.MARINE...
Northeasterly flow has set up over the eastern Great Lakes as an
area of high pressure has centered over Lake Superior. The NE flow
will remain at this direction through Saturday morning. These winds
will increase to 15-20 knots Friday morning and again Friday night,
while producing waves of 2 to 4 feet for the Lake Ontario nearshore
waters west of Sodus Bay. This has allowed small craft advisories
to be issued.

Winds appear to have enough of an easterly component near the
Niagara River such that a SCA will not be needed.

On Lake Erie...winds will yield the highest waves on the western
waters of the lake...with waves 3-5 feet from Ripley to Dunkirk
where a new Advisory has been issued.

Otherwise, high pressure over the eastern Great Lakes will bring
fine boating conditions continuing through the weekend.

&&

.TIDES/COASTAL FLOODING...
A storm system developing over the Middle Atlantic states
today into Saturday will combine with high pressure over the
Upper Great Lakes to produce some elevated northeasterlies on
Lake Ontario. Recent model guidance has backed off on the
strength of the northeast winds, now only 15-20 knots, such
that the risk for additional significant erosion and flooding
along the south shore of the lake is now reduced. Have cancelled
the lakeshore flood watch for Niagara county to Wayne county
with waves only expected to reach 2-4 feet.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 2 AM EDT
         Saturday for LEZ040.
         Small Craft Advisory until 6 PM EDT Saturday for
         LOZ042-043.

&&

$$

SYNOPSIS...RSH/SMITH
NEAR TERM...RSH/SMITH
SHORT TERM...ZAFF
LONG TERM...CHURCH
AVIATION...SMITH
MARINE...SMITH
TIDES/COASTAL FLOODING...SMITH



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