559
FXUS61 KBUF 312300
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
700 PM EDT Fri Jul 31 2026

.WHAT HAS CHANGED...
Have increased precipitation chances for Monday.

&&

.KEY MESSAGES...
1) Mainly dry weather expected through Saturday.

2) Showers and thunderstorms develop for Saturday night-Monday, with
locally heavy rainfall again becoming possible.

&&

.DISCUSSION...
Key Message 1...Mainly dry weather expected through Saturday.

Ridging at the surface and aloft will crest across our area this
evening...then will slide eastward and out across New England
tonight and Saturday. Meanwhile...a broad upper level trough over
Ontario and Quebec will extend southward and begin to phase with a
compact but vigorous shortwave trough making its way across the
Upper Midwest and Lower Ohio Valley...resulting in a sharpening/
deepening upper trough extending all the way from Hudson Bay to the
Ohio Valley Saturday evening.

For the most part...the departing ridging should maintain enough of
an influence on our region to keep our area mainly dry through the
day Saturday. That said...with the eastern edge of the above trough
beginning to encroach upon our region...can`t completely rule out a
couple isolated showers/storms skirting by our northwestern
periphery later tonight/Saturday...and then developing along/inland
from developing lake breeze boundaries over WNY Saturday afternoon
with diurnal heating and an uptick in humidity levels.

Key Message 2...Showers and thunderstorms develop for Saturday night-
Monday, with locally heavy rainfall again becoming possible.

Latest guidance suite suggests that the sharp/narrow upper level
trough will continue to slowly push eastward during the second half
of the weekend into early next week...with the southern end of the
trough likely breaking off and consolidating into a slow-moving
closed low somewhere between the Ohio Valley and mid-Atlantic states
sometime in the Monday-Tuesday time frame. At the surface...a rather
wavy cold front will slowly push eastward across southern Ontario
and then across our region sometime between Sunday and the first
part of Monday...with another broad surface low then forming
underneath the closed low early next week.

Model guidance continues to struggle with the evolution of this
pattern Sunday through early next week...particularly with respect
to the timing and placement of the developing cutoff low...in which
a considerable degree of uncertainty persists. This being said...a
notable general trend over the last 24 hours is for a slowing of the
frontal boundary and its eventual passage across/departure from our
region. With this in mind the attendant next round of unsettled
weather now is looking more likely to extend into Monday...though
both faster or slower departures of this remain plausible at this
point given continued model inconsistencies and the resulting degree
of forecast uncertainty.

What still appears more certain is that increasingly unsettled
conditions will begin Saturday night...then will continue through
Sunday/Sunday night as the upper trough axis and wavy cold front
approach...then work into our region. During this time the deep
south-southwesterly flow out ahead of this system will spread a
plume of rich Gulf-based moisture across our region...with PWATs
increasing to near 2 inches. Within this environment...warm
advection/isentropic ascent will result in increasing probabilities
for showers and thunderstorms across our area Saturday night and
Sunday...with this further aided during Sunday by the approach of
the front/trough axis...increasing low level convergence along the
nose of a 30-40 knot low level jet...and the development of weak to
modest diurnally-driven instability. Given the high atmospheric
moisture content and near-parallel nature of the low-mid level flow
to the approaching front and trough axis...the potential will exist
for storms with heavy rainfall to develop and train out ahead
of/along the approaching frontal boundary Sunday into Sunday
night...which could in turn pose a risk for localized flash
flooding. This remains well captured by WPC`s Marginal risk for
excessive rainfall for far western New York for Saturday night...and
the entire area for Sunday/Sunday night. While a decent amount of
deep-layer shear (30-40 knots) does look to develop across far WNY
on Sunday and then linger across our region through Sunday
night...the presence of only weak to at best modest instability
currently looks to largely preclude much of an organized severe
weather threat.

As mentioned above...with the slower trend to the passage of the
front/trough axis there now appears to be a decent likelihood that
at least some showers/storms will linger into Monday as well...and
with this in mind have upped PoPs for the start of the new work
week. Depending upon exactly what happens with the evolution of the
closed low...at least some chance for showers/storms may then linger
through the middle of next week.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR will continue to prevail tonight through Saturday as surface
high pressure drifts to the eastern seaboard. An expansive shield of
dense, high cirrus will increase from west to east across the
eastern Great Lakes overnight in advance of the next system.

The high clouds will lower into a mid level deck on Saturday.
Increasing moisture, diurnal instability, and the arrival of a weak
mid level trough may support a few widely scattered showers and
thunderstorms across Western NY by late afternoon or evening, but
dry weather and VFR will continue to prevail until then.

Outlook...

Saturday night through Sunday night...Increasing chances for rain
Sunday, with thunderstorms and locally heavy downpours. Sub-VFR
conditions expected with periods of IFR likely.

Monday through Wednesday...Mainly VFR, however afternoon and evening
scattered showers and thunderstorms will pose a risk for MVFR
conditions at times.

&&

.MARINE...
Weak high pressure will remain across the Lower Lakes Region through
this evening...before slowly drifting off the Atlantic coastline
through Saturday. This will provide us with generally light to
modest winds and minimal wave action through Saturday...with the
weak pressure gradient allowing for local lake breeze circulations
and onshore flow this afternoon.

Between Saturday night and the first part of Monday a wavy cold
front will slowly make its way east from the central Great Lakes and
across Lakes Erie and Ontario...with a light to modest south to
southeasterly flow out ahead of the front giving way to a northerly/
northeasterly flow of similar strength following its passage.

Of more concern to marine interests will be the showers and
thunderstorms that are expected to accompany the approach and
passage of the front...some of which could contain locally heavy
downpours/greatly reduced visibility and locally higher winds and
waves.

&&

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

&&

$$

DISCUSSION...JJR
AVIATION...Hitchcock
MARINE...JJR