563
FXUS61 KBUF 171005
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
605 AM EDT Mon Aug 17 2026

.WHAT HAS CHANGED...
Only minor changes with this forecast update.

&&

.KEY MESSAGES...
1.) Isolated showers and thunderstorms today will be followed
by dry weather tonight through Tuesday.

2.) Another round of isolated to scattered showers and
thunderstorms is forecast for the midweek period.

&&

.DISCUSSION...
Key Message 1...Isolated showers and thunderstorms today
will be followed by dry weather tonight through Tuesday.

Cyclonic W`erly flow aloft and embedded shortwave troughs impact
Western and Central NY through this early evening. At the
surface, a cold front was located just east of Barrie, ON, just
west of Hamilton, ON, and extended generally S`ward across
central Lake Erie at 2:20 AM EDT this morning. This front should
sweep E`ward across our CWA between about 3 AM and 1 PM EDT
today. Ahead of and behind the front, subtle surface trough
axes attendant to the shortwave troughs aloft will traverse
Western and Central NY generally from west to east. In addition,
behind the front, a surface ridge will build slowly from the
Upper Midwest and vicinity. Isolated and periodic showers and
thunderstorms are expected through this early evening as low-level
convergence and moist ascent along the cold front and surface
trough axes release weak boundary layer CAPE. However, the
threat for these showers and storms should end gradually and
generally from west to east late this morning through early
evening as the building surface ridge is accompanied by a
lowering, strengthening, and stabilizing subsidence inversion.
Lows should reach the 60`s around daybreak this morning. Highs
should reach the 70`s to lower 80`s late this afternoon, behind
the weak cold front and amidst partly to mostly cloudy sky.

The high pressure ridge at the surface and aloft will build
from the western Great Lakes and vicinity tonight through
Tuesday. Stabilizing subsidence accompanying the ridge is
expected to promote dry weather. Considerable clearing and weak
or calm surface winds accompanying the ridge should contribute
to lows reaching the 50`s to lower 60`s around daybreak Tuesday.
Steam fog should form in the river and lake valleys of the
Western Southern Tier, Finger Lakes, and Eastern Lake Ontario
Region late this evening and especially during the predawn hours
of Tuesday morning. Patchy radiation fog should also form
during the same time period, especially inland from Lakes Erie
and Ontario, amidst lingering low-level moisture from recent
rainfall. Fog will dissipate via the onset of diurnal convective
mixing of the boundary layer shortly after daybreak. Highs are
forecast to reach the 70`s to lower 80`s late Tuesday afternoon.

Key Message 2...Another round of isolated to scattered showers and
thunderstorms is forecast for the midweek period.

The above-mentioned ridge at the surface and aloft exits E`ward
Tuesday night and allows a warm front to sweep N`ward through
Western and Central NY. Simultaneously, cyclonic W`erly flow
aloft becomes established over our area and embedded shortwave
disturbances traverse Western and Central NY. The cyclonic
W`erly flow aloft and embedded shortwave disturbances should
continue to affect our area on Wednesday, when a cold front
should sweep SE`ward through Western and Central NY. Isolated
to scattered showers and thunderstorms are expected after
midnight Tuesday night through Wednesday as weak to perhaps
moderate CAPE, included elevated CAPE, is released by the
following: moist isentropic ascent along the upper-reaches of
the warm front and ahead of shortwave trough axes; low-level
convergence and moist ascent along the surface warm front,
surface cold front, and surface trough axes attendant to the
shortwave troughs. Overnight lows should reach mainly the mid
50`s to mid 60`s Tuesday night and be followed by daytime highs
in the 70`s to 80F on Wednesday.

During Wednesday night through Thursday, a ridge at the surface
and aloft is expected to build from the western Great Lakes and
vicinity. Primarily fair weather is expected in Western and
Central NY as stabilizing subsidence accompanies the ridge.
However, a few rain showers associated with moist isentropic
ascent along the upper-reaches of the departing cold front may
impact the Western Southern Tier and southern Finger Lakes
Wednesday evening. Latest trends in NWP model guidance suggest
the cooler air mass behind the cold front may be too dry and not
cold enough to support a period of lake-effect rain. Overnight
lows should reach the upper 40`s to near 60F around daybreak
Thursday as the cooler air mass overspreads our region behind
the cold front. Highs should reach the 70`s late Thursday
afternoon.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
W`erly flow aloft and embedded disturbances affect Western and
Central NY through 12Z/Tues. At the surface, a cold front was
located just east of KROC and just west of KELZ at 10Z/Mon.
This front will continue moving E`ward and should exit the rest
of our area by 17Z/Mon. Behind the front, a high pressure ridge
builds very slowly from the Upper Midwest through ~00Z/Tues and
then builds in earnest through 12Z/Tues. Our regional surface
winds trend SW`erly around 5 to 10 knots ahead of the cold front
and W`erly to NW`erly around 5 to 10 knots behind the front.
Surface winds are then expected to be light and variable or calm
between ~00Z/Tues and 12Z/Tues. Isolated showers and
thunderstorms with brief MVFR to IFR will end generally from
west to east late this morning through early evening.

Widespread MVFR to IFR ceilings should rise to near 3.5kft to
5kft AGL late this morning through early evening and generally
from west to east as stratocumuli evolve into diurnal cumuli.
The cumuli will then dissipate around sunset this evening and
give way to mainly clear sky with a few passing cirrus
accompanying the aforementioned disturbances. Weakening surface
winds and lingering low-level moisture should lead to mist and
fog between ~03Z/Tues and 12Z/Tues, especially inland from Lakes
Erie and Ontario and along/near the lake and river valleys of
the Western Southern Tier, Finger Lakes, and Eastern Lake
Ontario Region, including KART and especially KJHW. Conditions
will vary between MVFR and LIFR in the mist/fog.

Outlook...

Tuesday...Dry weather and mainly VFR. Any lingering mist/fog is
expected to dissipate by mid-morning.

Tuesday Night and Wednesday. Isolated to scattered showers and
thunderstorms with MVFR or worse conditions expected.

Wednesday Night through Friday...Dry weather and mainly VFR,
although localized fog in/near river/lake valleys is possible
around daybreak on Thursday and Friday.

&&

.MARINE...
Wind speeds around 5 to 15 knots and waves of 3 feet or less are
expected through this Friday. A cold front will sweep E`ward
across eastern Lake Erie and Lake Ontario this morning and cause
SW`erly winds to veer to W`erly to NW`erly. Behind the front, a
trough lingers over the lakes today before a high pressure ridge
builds from the Upper Midwest tonight. Winds should vary between
mainly W`erly and N`erly. On Tuesday, the ridge axis should move
E`ward across eastern Lake Erie and Lake Ontario, and cause winds
to back to SW`erly. A cold front should sweep SE`ward across eastern
Lake Erie and Lake Ontario Wednesday and cause SW`erly winds to
veer to NW`erly to N`erly. Behind the cold front, a ridge should
build from the Upper Midwest and western Great Lakes through
Friday and cause winds to become variable in direction.

&&

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

&&

$$

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