990
FXUS61 KBUF 211034
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
634 AM EDT Tue Jul 21 2026

.WHAT HAS CHANGED...
Updated precipitation chances based on trends of upstream radar
and lowered probability of showers today due to uncertainty in
timing of showers and thunderstorms.

&&

.KEY MESSAGES...
1) Conditions are favorable for isolated to scattered severe
thunderstorms through this evening.

2) Cool Wednesday, with a chance of a few lingering showers and
isolated thunderstorms.

&&

.DISCUSSION...
Key Message 1...Conditions are favorable for isolated to scattered
severe thunderstorms through this evening.

GOES water vapor imagery shows multiple shortwave troughs embedded
in a deep trough across the Great Lakes region this morning. One
shortwave in particular will move across the eastern Great Lakes
region today. Convection is ongoing near a warm front across
eastern Ontario this morning. Showers and a few thunderstorms
are expected to move into the Niagara Frontier through mid-
morning.

Mid level height falls, DPVA, and upper level divergence ahead of
the trough are expected to contribute to a background of large scale
ascent today. A warm front will move across the region today
ushering in deep southwesterly flow and moisture with dewpoints
climbing into the upper 60s to low 70s today. The warm front will be
the first focus of convection today with showers and thunderstorms
moving east across western NY. This convection will move into north-
central NY this afternoon, while additional convection north of Lake
Ontario moves into the North Country as well, and may lead to a more
prolonged period of rain east of Lake Ontario today. Instability is
expected build slowly across the region due to debris clouds and
showers. Some hi-res models such as the HRRR shows a lull of
convection across western NY this afternoon. An increasing southwest
flow will also contribute a stable lake shadow east of Lake Erie
this afternoon. Additional showers and thunderstorms are expected to
form along lake breeze boundaries across the Niagara Frontier and
east of Lake Erie this afternoon.

A strong cold front will move through the region this evening and
another round of showers and a few thunderstorms are expected. The
severe risk will continue this evening with strong low level
convergence and deep moisture ahead of the front.

While there remains uncertainty in overall coverage of
thunderstorms today, the combination of large scale forcing,
forecast surface based instability over 1000 J/Kg and curved
hodographs supports isolated to scattered severe thunderstorms
through this evening. The SPC maintains a Slight Risk across the
entire area with damaging winds as the main severe threat. An
isolated tornado and severe hail can`t be ruled out. The moist air
mass will also lead to the risk of localized flooding across the
region. The greatest risk of flooding will likely be associated with
boundaries where storms can backbuild.

Coverage of showers and especially thunder will diminish by mid to
late evening with the loss of diurnal instability.

Key Message 2...Cool Wednesday, with a chance of a few lingering
showers and isolated thunderstorms.

The digging trough will briefly develop into a mid level closed low
over western Quebec Wednesday. Deep moisture will be east of the
area by Wednesday morning, but forcing for ascent from several
shortwaves rounding the base of the trough coupled with cool air
aloft will still support a few scattered showers through the day,
and possibly an isolated thunderstorm or two. Both intensity and
coverage will be far less than Tuesday.

Temperatures will be quite cool Wednesday, close to 10F below
average for mid summer. Highs will struggle to reach the lower 70s
for lower elevations, with mid 60s across higher terrain. Lows
Wednesday night will drop back into the 50s in most areas, with mid
40s for the Southern Tier valleys and Lewis County.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Rounds of showers and thunderstorms with reduced flight
conditions are expected through tonight, with improving
conditions late tonight through Wednesday. The first round of
showers and thunderstorms is expected to move into KIAG/KBUF
between 12-14z this morning before moving east across the
remainder of western NY through the early afternoon. An
additional area of showers and thunderstorms is expected to move
into the North Country/KART mid-morning through early
afternoon. Additional showers and thunderstorms are expected to
develop on boundaries through this evening, with low confidence
on the timing of thunderstorms.

There is a Slight Risk of Severe Thunderstorms through this evening.
Some thunderstorms are capable of strong wind gusts, large hail and
torrential rain. Both visibility and ceiling restrictions are
possible at times.

Breezy today with south-southwest wind gusts between 20-30 knots,
highest gusts are expected at KIAG/KBUF this afternoon.

Outlook...

Wednesday...Restrictions likely with lingering showers/isolated
thunderstorm.

Thursday and Saturday...Mainly VFR.

&&

.MARINE...
South-southwest winds will increase on the Lakes today while
gradually veering more to the southwest. Small Craft Advisory
conditions are expected on Lake Erie, the west end of Lake Ontario,
and northeast end of Lake Ontario where winds are the strongest. A
cold front will move across the lower Great Lakes Tuesday night.
West to west- northwest winds will increase late tonight and
Wednesday, especially on Lake Ontario with solid Small Craft
Advisory conditions.

Several rounds of showers and thunderstorms are expected from late
morning through evening Tuesday. A few storms may contain gusty
winds and locally higher waves.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 10 AM this morning to 9 PM EDT this
         evening for LEZ020.
         Small Craft Advisory from 10 AM this morning to midnight
         EDT tonight for LEZ040-041.
         Small Craft Advisory from 10 AM this morning to 6 AM
         EDT Thursday for LOZ042.
         Small Craft Advisory until 10 AM EDT Thursday for LOZ045.

&&

$$

DISCUSSION...Hitchcock/HSK
AVIATION...HSK
MARINE...HSK