Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 202351
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
751 PM EDT Wed Sep 20 2017

.SYNOPSIS...
Warm temperatures and dry conditions will persist through the
remainder of the week and the coming weekend, as high pressure will
remain in place across the region.

&&

.NEAR TERM /THROUGH THURSDAY/...
Skies have cleared out early this evening outside of some high
thin clouds clipping the Eastern Lake Ontario region. The clear
skies and light winds will set the stage for another foggy
night for many areas later tonight and into early Thursday
morning, particularly in river valleys and near lakes/ponds.
Like last night, fog and low stratus is again likely to develop
along the south shores of Lake Ontario. This cloud cover will
linger into Thursday morning before dissipating by Thursday
afternoon.

With ideal conditions for radiational cooling and slightly
lower dewpoints, we should see cooler temperatures as compared
to Tuesday night, with lows in the 50s, with a few lower 60s
near Lake Erie.

Thursday will be another near carbon-copy of today with perhaps the
only differences being the mid-level ridge strengthening to 588dm
and 850mb temps warming a degree to +17C. The high pressure surface
and aloft will keep dry and warm weather in place with high temps
again warming into the low to mid 80s or 10-15 degrees above normal
September levels. Dewpoints holding in the 60s will keep a humid
feel to the airmass.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
The calendar will remain turned back a couple months through this
period...as an anomalously strong 590dm sub tropical ridge will
remain anchored over the Ohio Valley and Lower Great Lakes. This
prodigious ridge will be accompanied by equally exceptional warmth.

H85 temps tat will start off in the mid teens C Thursday night will
further warm to the upper teens C for the weekend. This will
encourage additional day to day warming so that by Saturday...max
temps will be in the mid to upper 80s F. Given the increasingly dry
antecedent conditions...its not out of the question that select
locations in the Genesee Valley (ie. Dansville) and in the typically
warmer valleys of the Southern Tier would reach 90. If this were mid
summer (when the sun angle would be more than 20 deg greater) then
we would possible be talking about some oppressive heat. Luckily for
us...the Gulf of Mexico will be cut off..so dew points that will
start off in the upper 50s to lower 60s will not climb past 65 by
late in the weekend.

Meanwhile the nights will feature mainly clear skies with the
resulting favorable radiational cooling producing fog in open...
outlying areas...and particularly in the Southern Tier valleys. Mins
will range from the mid and upper 50s across the Southern Tier and
parts of the North Country to the low to mid 60s across the lake
plains.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A very high confidence forecast remains in place for the
unseasonable warmth to continue during this three day period...as a
high amplitude ridge will remain intact across the eastern third of
the country. The only problem will be the possible effects from
Hurricane Maria...which by Wednesday will likely be churning
northward of the mid Atlantic coast. While the ridge will keep us
rain free through at least Tuesday...there have been some medium
range ensembles that are suggesting that some Atlantic moisture
could work back across the region late Tuesday night and Wednesday.
From this vantage point though...the odds favor continued dry
weather...but will introduce slgt chc pops as we end the seven day
period.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Expect VFR conditions to prevail through the evening hours,
however with high pressure, light winds, and clear skies in
place tonight, expect fog to redevelop again tonight after
03-06Z. Tonight should be somewhat similar to last night, except
that the northeasterly flow will be stronger across the eastern
half of Lake Ontario rather than the western half. Stratus and
fog is again likely to form along the south shores of Lake
Ontario. Following HRRR guidance which had a good handle last
night, this should be most widespread from Rochester to Syracuse
which is downwind of a NNE surface flow. Fog will also form in
the river valleys, impacting Jamestown. Elsewhere fog will be
patchy, but it is difficult to rule out at any given location.

Visibility will vary in radiation fog, but there is a potential
for VLIFR conditions in dense fog at times. This has the
greatest chance to impact ROC/JHW, but cannot completely be
ruled out at any terminal location.

Stratus will linger south of Lake Ontario during the morning
hours Thursday, with lingering IFR conditions in low cigs. This
will dissipate by Thursday afternoon with VFR conditions.

Outlook...

Thursday night through Monday...VFR. Local IFR conditions each
late night and early morning with fog.

&&

.MARINE...
High pressure will remain in place across the Lower Great Lakes
right through next weekend. This will provide a long stretch of very
light winds and flat wave action for the rest of the week and
weekend with ideal boating conditions, but not much wind for sailing.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...CHURCH/SMITH
NEAR TERM...APFFEL/SMITH/WOOD
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...APFFEL
MARINE...HITCHCOCK/THOMAS



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