402
FXUS61 KBUF 310800
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
400 AM EDT Fri Jul 31 2026

.WHAT HAS CHANGED...
The potential for showers and thunderstorms with periods of
heavy rainfall continues to increase this Saturday night through
Sunday night.

&&

.KEY MESSAGES...
1) Primarily dry weather is expected through Saturday.

2) Showers and thunderstorms develop for the second half of the
weekend, bringing the potential for another round of heavy
rainfall.

&&

.DISCUSSION...
Key Message 1...Primarily dry weather is expected through Saturday.

A high pressure ridge at the surface and aloft builds and then
crests E`ward across Western and Central NY today so that by
sunset this evening, the surface ridge axis will become located
near Lake Champlain and Long Island. Stabilizing subsidence
accompanying the ridge will promote fair weather. Considerably
clear sky, weak surface winds, and lingering low-level moisture
from recent rainfall will continue to allow patchy radiation fog
and river valley steam fog to develop through daybreak this
morning. Fog is then expected to dissipate by late morning,
following the onset of diurnal convective mixing of the boundary
layer. Daytime heating and the development of synoptic-scale
low-level warm air advection as our CWA becomes located along
the western flank of the surface ridge will allow highs to reach
mainly the upper 70`s to mid 80`s late this afternoon. The
coolest highs are expected in the higher terrain of the Western
Southern Tier, Finger Lakes, and Eastern Lake Ontario Region, as
well as along and very near the shores of ~74F Lake Erie and
~73F Lake Ontario due to lake breeze development late this
morning through early evening.

Current odds favor fair weather persisting tonight through
Saturday as the aforementioned ridge exits very slowly E`ward
and a positively-tilted shortwave trough approaches from the
western Great Lakes and vicinity. However, moist isentropic
ascent aloft, ahead of the shortwave trough axis, may release
sufficient elevated CAPE to generate very isolated showers and
thunderstorms over western Lake Ontario and vicinity during the
predawn hours of Saturday morning. Even so, the chance of this
shower/storm development is only 20% at most. Overnight lows
should reach mainly the mid 50`s to mid 60`s around daybreak
Saturday and be followed by late afternoon highs reaching mainly
the 80`s. Humidity will increase tonight and especially on
Saturday as more-direct low-level warm/moist air advection from
the Gulf and southern Gulf Stream becomes established.

Key Message 2...Showers and thunderstorms develop for the second
half of the weekend, bringing the potential for another round
of heavy rainfall.

The above-mentioned shortwave trough axis should move from the
western Great Lakes to near western New England and NJ during
Saturday night through Monday night. At the surface, the
attendant cold front should approach our region from the
northwest Saturday night through Sunday before drifting SE`ward
across our CWA Sunday night through early Monday afternoon as
multiple lows move NE`ward along the front. Behind the front and
shortwave trough axis, a high pressure ridge at the surface and
aloft should build slowly from the western Great Lakes and
vicinity Sunday night through Monday night. Periods of scattered
to widespread showers and thunderstorms are expected Saturday
night through Sunday night as weak to moderate instability,
including elevated CAPE, is released by convergence/moist ascent
along the front and moist-isentropic ascent ahead of the
shortwave trough axis. A SW`erly 30-40 knot LLJ should
overspread our region ahead of the cold front overnight Saturday
night into Sunday and enhance the moist isentropic ascent. This
LLJ will slowly exit our region to the south and east Sunday
night through early Monday afternoon as the cold front drifts
SE`ward. Unusually-high PWAT`s within the low-level warm/moist
air advection regime from the Gulf and/or southern Gulf Stream
should allow convection to produce periods of heavy rainfall.
SW`erly mean mid-level flow should exhibit a large component
parallel to the LLJ`s major axis and cold front, and allow
convection to train. Thus, localized flash flooding remains a
concern. WPC still has WNY in a marginal risk of excessive
rainfall (level 1 of 4) Saturday night and our entire CWA in a
slight risk of excessive rainfall (level 2 of 4) Sunday into
Sunday night. Additional and isolated showers and thunderstorms
are possible on Monday, ahead of the shortwave trough axis and
especially along and ahead of the surface cold front. Deep-layer
bulk shear strengthening to moderate to strong magnitudes may
support stronger storms Saturday night through Sunday and into
Monday, but the potential for stronger storms will be contingent
on multiple factors, including the magnitude of instability.
Dry weather is expected to return region-wide by Monday night as
stabilizing subsidence accompanies the aforementioned ridge.

Lows should reach mainly the 60`s overnight Saturday night.
Highs should reach the 70`s Sunday afternoon. Lows should reach
mainly the mid 50`s to mid 60`s around daybreak Monday. Daytime
highs should reach the 70`s on Monday and be followed by
overnight lows in the lower 50`s to lower 60`s around daybreak
Tuesday as a somewhat cooler and drier air mass overspreads our
region behind the cold front.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
VFR flight conditions will continue overnight as an upper level low
exits farther to the east and weak surface high pressure builds
towards our region. Residual moisture will allow for patches of fog
to form, especially across eastern zones where showers occurred
Thursday. This may bring fog into the KART airfield. River
valley fog forming in the Southern Tier may expand up and over
the KJHW terminal. Will place some periods of IFR visibility
into the KJHW TAF.

Fog will dissipate between 12-13Z this morning with VFR flight
conditions and a light wind through the remainder of the TAF cycle.

Outlook...

Friday night and Saturday...Mainly VFR.

Saturday night through Sunday night...Periodic showers and
thunderstorms with locally heavy downpours and associated reductions
to MVFR to LIFR, especially from later Saturday night through Sunday
evening.

Monday and Tuesday...Mainly VFR and dry, though a few widely
scattered showers/storms and associated restrictions cannot be ruled
out both days.

&&

.MARINE...
A high pressure ridge builds from the west today and then exits
slowly E`ward from eastern Lake Erie and Lake Ontario through
Sunday. Variable winds around 5 to 10 knots and waves of 2 feet
or less are expected. Winds will trend onshore late this morning
through early evening due to Lake Erie and Lake Ontario lake
breeze development.

A cold front and inverted trough should drift SE`ward across
eastern Lake Erie Sunday night and Lake Ontario Sunday night
through Monday morning as multiple lows move NE`ward along the
front. The passage of the front and lows should cause mainly
SE`erly winds around 5 to 10 knots ahead of the front to shift
to N`erly to NW`erly behind the front. Waves are expected to
remain mainly 2 feet or less. Note: periodic showers and
thunderstorms are expected along and ahead of the cold front
Saturday night through Monday morning. Some showers and storms
should produce localized downpours with greatly reduced
visibility and higher winds and waves.

Behind the front, another high pressure ridge builds from the
western Great Lakes through this Tuesday. In response, winds
should become variable around 5 to 10 knots once again. Waves of
2 feet or less are expected.

&&

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

&&

$$

DISCUSSION...Jaszka
AVIATION...TMA
MARINE...Jaszka