Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 251824
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
224 PM EDT Mon Sep 25 2017

.SYNOPSIS...
High pressure will keep dry weather and midsummerlike warmth across
our region through most of Wednesday. An approaching cold front may
finally bring a chance of a few light showers late Wednesday and
Wednesday night...with much cooler temperatures then following for
Thursday right on through next weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
For the rest of the day...ridging at all levels will continue to
provide our area with dry weather and plentiful sunshine. In terms
of cloud cover...just some very thin/high cirrus will continue to
work across the area from southwest to northeast...with some scattered
diurnal cumulus also developing across western New York in tandem
with a subtle increase in low level moisture. The big story though
will continue to be the midsummerlike heat...with 850 mb temps of
+19C to +20C supporting widespread upper 80s to lower 90s across the
lower elevations...with slightly cooler readings across the higher
terrain and along the immediate lakeshores. The previous record
high temperature for Buffalo (87 in 2007) has already been eclipsed
with an 89 degree reading as of this writing...and we will likely
tack on another couple of degrees to this before temps peak around
mid afternoon. Elsewhere...the record high for Rochester (92, also
in 2007) should be at least approached before the Lake Ontario lake
breeze arrives...while the record at Watertown (89) currently appears
safe.

Tonight...high pressure will remain in place with any diurnal cumulus
over WNY quickly fading with the loss of heating...while thin/high
cirrus continues circulate across our region aloft. Much like last
night...nocturnal cooling of our moist boundary layer and light winds
should result in areas of valley fog redeveloping across the Southern
Tier...while patchier/lighter fog develops elsewhere. Otherwise it
will be a very mild night by late September standards...with lows
ranging from the lower 60s across the North Country and interior
portions of the Southern Tier to the mid and upper 60s elsewhere.

On Tuesday...Hurricane Maria will be slowly moving northward offshore
of the Carolina coastline...while a modest midlevel trough presses
from the northern Plains into the Upper Mississippi Valley. Meanwhile
our region will continue to lie in the squeeze play/ridging separating
these two systems...albeit with the main upper ridge axis sliding a
bit to our south and weakening slightly. With a little bit more in
the way of low level moisture available to work with and strong
heating of our very warm and humid airmass again expected...it is not
entirely out of the question that (as suggested by some guidance) we
could pop an isolated afternoon shower or two across interior sections
of far western New York...though with the mid levels remaining very
dry and possibly capped...will continue to advertise a dry forecast
for now. Otherwise it will be another mostly sunny and unseasonably
warm to hot day with widespread highs in the 85-90 range again
anticipated...with the warmest readings most likely to lie from the
Genesee Valley eastward...where supporting 850 mb temps will be the
warmest. Record highs for September 26th are 87 at Buffalo (1959)...
89 at Rochester (1900)...and 82 at Watertown (1970)...with the
Watertown record currently appearing in serious jeopardy and the
records at Buffalo/Rochester likely to at least be very closely
approached.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
Tuesday night and Wednesday will be the last of the recent summer-
like warmth for the region.  In addition, some areas will see their
first chance for rain in about 2 weeks arriving Wednesday with one
or two prefrontal frontal troughs and/or afternoon lake breeze
boundaries.  The front itself will likely be a dry frontal passage
for Western NY.  Expect it to ease into the region Wednesday evening
with scattered convection well ahead of it over central NY.

Thursday should be dry but with ample strato-cumulus under an
upslope northwest flow. It`s possible a few sites might see a
sprinkle or two, but the main story will be the ~20F drop in daytime
high temperatures.  While it may feel cool, the highs, mostly
in the 60s, will actually get us back our normal climatology.

Thursday night should be similarly dry with a continued drop in
temperatures resulting in lows in the 40s overnight.  This will
coincide with a surface ridge dropping from the upper Great Lakes
region into Western NY overnight.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
A much sharper longwave trough axis and secondary surface cold front
is shown in the models to drop across our region Friday or Friday
night. This will bring a chance of rain showers and another shot of
cold air advection. 00Z guidance has trended a bit stronger with
this shortwave, supporting slightly higher chances for showers and
slightly cooler temperatures behind the front. 850mb temps could
drop to or a few degrees below zero C Friday night or Saturday night
with a north to northwesterly flow over the lakes. Expect this
airmass to contribute to some lake enhancement behind the cold front
with a chance of showers south of the lakes Friday night into
Saturday.

High temperatures will generally be in the lower to mid 60s
throughout the period, except Saturday which will be a bit cooler
with highs around 60. Overnight lows will generally be in the 40s,
with the typically cooler interior valleys and North Country dipping
into the 30s Saturday night.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Ridging at all levels will continue to promote largely VFR conditions
through Tuesday...except from later tonight through mid-Tuesday morning
as LIFR/IFR river valley fog redevelops across the Southern Tier...and
patchier/lighter fog and IFR/MVFR conditions form elsewhere.

Outlook...
Tuesday night...VFR...except localized IFR/MVFR conditions in
developing Southern Tier valley fog overnight.
Wednesday...Mainly VFR with a chance of showers in the afternoon.
Thursday through Saturday...Mainly VFR...with a chance of showers
Friday and Saturday.

&&

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

A cold front will cross the region late Wednesday. Northwest winds
will increase in the wake of the cold front, and may bring a round
of advisory-worthy winds and waves to Lakes Erie and Ontario late
Wednesday through early Thursday.

&&

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

&&

$$

SYNOPSIS...HITCHCOCK/JJR
NEAR TERM...JJR
SHORT TERM...ZAFF
LONG TERM...APFFEL/SMITH
AVIATION...JJR
MARINE...HITCHCOCK/JJR


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