701
FXUS61 KBUF 231409
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1009 AM EDT Sat Aug 23 2025

.SYNOPSIS...
Increasing moisture and daytime heating well out ahead of an
approaching cold front will help to trigger some widely scattered
showers and perhaps a couple thunderstorms this afternoon...with the
bulk of these expected from interior sections of the Southern Tier
northeastward across the Finger Lakes. The cold front will slowly
approach and cross our region tonight and Sunday while bringing
additional showers and scattered thunderstorms. A much cooler
airmass following in the wake of the front will then bring unsettled
conditions and below normal temperatures for the first half of next
week.

&&

.NEAR TERM /THROUGH SUNDAY/...
An increasingly vertically stacked low over Ontario Province will
slowly make its way to James Bay this afternoon...with its trailing
cold front slowly pushing across the central Great Lakes. Well out
ahead of this...an increasing southerly return flow of warmer and
somewhat more humid air will reside across our region...and will
result in temps reaching the lower to mid 80s in most locations...
along with surface dewpoints climbing to moderately humid levels in
the lower to mid 60s.

As we push through the afternoon and early evening hours...a weak
surface trough will set up from interior portions of the Southern
Tier northeastward across the Finger Lakes to portions of the North
Country. As diurnal heating helps to make our increasingly more
humid airmass more buoyant over time...this boundary may help to
trigger some scattered showers and perhaps a couple thunderstorms in
the above areas this afternoon...with areal coverage then increasing
a bit further as we approach sunset. With the most recent update...
have sped up the timing of all this a little bit based upon some of
the more aggressive guidance and recent satellite imagery...the
latter of which is showing our airmass to already be somewhat
bubbly.

Tonight...the low spinning over James Bay will pivot its cold front
closer to the region, and the prefrontal trough will enter the Lower
Lakes. These two features will then bring additional chances for
showers and thunderstorms tonight into the day Sunday.

While 30-40 knots of bulk shear will be in place this afternoon into
early this evening...with only weak to modest instability (500-1000
J/kg of MUCAPE) anticipated feel that there won`t be much potential
for any stronger to marginally severe storms today. Any better
chances for this will likely lie across our far eastern zones Sunday
afternoon and early Sunday evening...when there *could* be a bit
better instability to work with depending both upon the timing of
the cold front...and cloud/pcpn coverage out ahead of it earlier in
the day.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
Sunday night through Tuesday night will feature temperatures 7 to 15
degrees below normal as a cold upper level trough passes through the
region. Temperatures at 850 hPa will lower to 4-6C which will fall
within the lower 10 percent per Buffalo sounding climatology.

This cold airmass will yield showers and thunderstorms, especially
during the afternoon hours. Steep lapse rates may even bring some
small hail, while lake effect rain will become embedded to the east
and southeast of the Lakes.

This lake effect rain, likely to begin late Sunday night with the
return of deeper synoptic moisture will likely be organized the
greatest through the overnight hours, retracting back to the
shoreline within a light overnight wind flow...and then become
cellular through the morning hours with the increasing mixing
heights.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
Surface high pressure will build back across the eastern Great Lakes
Wednesday, with diminishing northward bound bands of lake effect
rain.

Fair weather will then extend for the remainder of Wednesday through
the end of the work week, though we will need to watch a front late
in the week that may sag across our region with additional
showers...though models have low consensus of timing and placement
at this time.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
High pressure to maintain VFR across the region through this
morning. A few isolated showers and storms will be possible by this
afternoon which may bring brief restrictions. Otherwise...VFR will
prevail for most terminals.

Tonight...low pressure near James Bay will push a cold front towards
the region. This will bring additional chances of showers and
a few thunderstorms overnight.


Outlook...

Sunday...VFR/MVFR with scattered to numerous showers and
a few thunderstorms.

Monday and Tuesday...Mainly VFR with a chance of showers and
embedded thunder afternoons/early evenings. MVFR in lake effect rain
showers overnights into the mornings downwind of the Lakes.

Wednesday...Mainly VFR with diminishing lake effect rain showers
downwind of the lakes.

&&

.MARINE...
A modestly strengthening southerly to southwesterly flow over the
Lower Great Lakes will generate some modest chop...but conditions
are expected to remain below SCA levels. A few scattered showers and
perhaps an isolated thunderstorm will also become possible across
the eastern half of Lake Ontario this afternoon.

A cold front nearing the Lower Great Lakes tonight will then bring
additional chances for showers and thunderstorms...while a continued
moderately brisk southerly to south-southwesterly flow maintains a
modest chop. Far northeastern portions of Lake Ontario could
potentially see conditions approach SCA levels for a time...however
overall conditions should remain below advisory levels with the flow
directing the greatest wave action across Canadian waters.

The passage of the cold front Sunday and Sunday evening will then
usher a much cooler airmass across the Lower Great Lakes...which
will last through Wednesday. The increasingly unstable over-lake
environment will allow for more efficient downward transport of
higher momentum air from aloft down to the lake surfaces...and
should lead to a better likelihood of advisory-worthy conditions
during this time frame. It will also lead to some lake effect rain
showers off both lakes, as well as the potential for waterspouts
beginning as early as Sunday night.

&&

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

&&

$$

SYNOPSIS...AR/JJR
NEAR TERM...AR/JJR
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...AR
MARINE...AR/JJR