C, New York Weather Forecast Discussion

842
FXUS61 KBUF 211047
AFDBUF
Area Forecast Discussion
National Weather Service Buffalo NY
647 AM EDT Sun Sep 21 2025
.SYNOPSIS...
After a cool start for some, it will feel like summer across
the region today, with temperatures expected to reach the upper
70s to low 80s with a touch of humidity. A few showers and an
isolated thunderstorm are possible across far western NY, before
a pattern shift brings on and off showers and thunderstorms
across western and north-central NY through mid-week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure over New England this morning, will move just
off the east coast today. A return flow around the high is keeping
temperatures elevated (60s) across far western NY, whereas
temperatures are down to the 30s across parts of the North Country
this morning. A Frost Advisory continues for Jefferson and Lewis
counties until 8AM today.
Warm air advection is ongoing aloft and daytime mixing and southerly
flow will transport summer-like air to the surface today. High
temperatures will average about 10 degrees above normal with highs
in the upper 70s, to the low to mid 80s across the Niagara Frontier
and Genesee Valley. Moisture advection will also take place today,
with dewpoints climbing into the low 60s across far western NY by
afternoon. Weak instability is expected across far western NY by
this evening. Widely scattered showers and a thunderstorm are
possible. Further east, a capped environment will keep things dry,
mainly east of the Genesee Valley.
A broad southwesterly flow will set-up across the region tonight.
Mid-level moisture will increase ahead of an approaching shortwave
trough. Activity that develops across the Ohio Valley today, may
move into western NY/Niagara Frontier late tonight, however the
chance for showers remains low. Dry weather will continue across
interior locations of western NY and into north-central NY tonight.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
During this period a rather broad upper level trough will dig east-
southeastward across the Great Lakes...with its axis settling across
New York State by late Tuesday night. At the surface...this will
encourage its corresponding broad/wavy cold frontal boundary to
gradually slip southeastward to the Lower Great Lakes by Tuesday
morning...then across our area sometime between Tuesday and Tuesday
night...with the guidance suite continuing to exhibit a fair amount
of variance on the timing of this boundary. As these features and
embedded shortwave impulses shift eastward and interact with
increasing amounts of Gulf-based moisture (PWATs climbing to between
1.5 and 1.75 inches) streaming northeastward into our region...we
will see a trend toward increasingly unsettled weather as we push
through Monday and Tuesday.
During Monday...this will be tied to the approach of an initial lead
shortwave impulse and the possible development of a lake breeze
boundary just to the lee of Lake Erie...which in tandem with modest
diurnally-driven instability should help to generate fairly numerous
showers and at least a few thunderstorms across far western New York
during the afternoon. The greatest overall pcpn potential/coverage
should then follow for Monday night and Tuesday as the main frontal
boundary and an associated surface wave ease their way into/across
our region...with the axis of most numerous showers probably tending
to push somewhat southward to the Southern Tier/interior Finger
Lakes in tandem with the frontal boundary during the day Tuesday.
Meanwhile thunder potential should wane at least somewhat with the
loss of heating Monday night...before redeveloping again along/south
of the slowly advancing front on Tuesday. Both pcpn and thunder
chances will then tend to wane from north to south Tuesday night
following the passage of the frontal boundary/surface wave...though
with the exact timing of this remaining unclear have retained chance
PoPs through Tuesday night.
At present...potential rainfall amounts through this period look to
average on the order of one half inch to an inch...with the caveat
that actual coverage will likely be uneven due to expected
convective influences...with some areas seeing more rainfall than
others. This being said...at this point any rainfall will be welcome
given the rather parched conditions we`ve seen of late.
As for temperatures...these will continue to average out above
normal in spite of a general cooling trend driven by the increased
cloud/pcpn coverage and the eventual introduction of cooler air
behind the surface front. This will especially due to nighttime
temperatures that will range a solid 5-10 degrees above normal for
this point in September.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A positively tilted aggregate trough will initially extend from the
Canadian Maritimes back to the central Plains on Wednesday...with a
mid-level ridge and associated wedge of sfc high pressure building
southward and likely leading to a general drying trend across our
area Wednesday and (especially) Wednesday night.
After that...forecast uncertainty increases for the latter portions
of the work week and the start of next weekend. Once the main part
of the trough peels eastward into the Canadian Maritimes...several
embedded waves within the western portion will likely phase both
with one another and an additional weak trough dropping south from
Manitoba later in the week...leading to the development of a new
closed upper level low somewhere over the Mississippi Valley. While
some of the 00z operational guidance suite has trended toward a more
southerly/suppressed nature to this next system as it slowly works
its eastward during the late week period...previous model runs and
ensemble guidance have indicated more divergent solutions. With both
this and the resultant forecast uncertainty in mind...the low chance
PoPs currently advertised by blended guidance look quite reasonable
as this system slowly trudges its way eastward in the Thursday-
Saturday time frame. Otherwise...temperatures should continue to
average out a little above normal.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A brief period of MVFR conditions are possible across the
western Southern Tier including KJHW this morning.
VFR conditions will continue across western and north-central NY
through tonight. Dry weather is mainly expected across the region,
with a low chance for showers and a thunderstorm at KBUF and KIAG
this afternoon through tonight.
Outlook...
Tonight...Mainly VFR with scattered to numerous showers and a
couple isolated thunderstorms developing across western New
York.
Monday and Tuesday...VFR/MVFR with showers likely along with a few
thunderstorms.
Wednesday...VFR/MVFR with a chance of showers.
Thursday...Mainly VFR with a chance of showers.
&&
.MARINE...
A moderate southeasterly flow is expected today, with winds veering
more southerly and picking up a bit across both Lake Erie and Lake
Ontario tonight. Speeds should remain below 15 knots today, though
winds will increase to up to 20 knots tonight, especially in the
eastern basins of Lake Erie and Lake Ontario. A Small Craft
Advisory is in effect for the eastern basin of Lake Erie and
the eastern shore of Lake Ontario tonight.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Frost Advisory until 8 AM EDT this morning for NYZ007-008.
MARINE...Small Craft Advisory from 8 PM this evening to noon EDT Monday
         for LEZ040-041.
         Small Craft Advisory from 8 PM this evening to noon
         EDT Monday for LOZ045.
&&
$$
SYNOPSIS...HSK
NEAR TERM...HSK
SHORT TERM...JJR
LONG TERM...JJR/PP
AVIATION...HSK
MARINE...EAJ/HSK/TMA

NWS BUF Office Area Forecast Discussion