-- Discussion containing changed information from previous version are highlighted. --
364
FXUS61 KBUF 251823
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
223 PM EDT Tue Jun 25 2024

.SYNOPSIS...
Warm and humid conditions today will last into Wednesday, along with
increasing chances of showers and some thunderstorms, especially on
Wednesday. Cooler and less humid conditions expected Thursday and
Friday. Active weather returns Saturday as a cold front crosses the
region.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Surface ridge will continue to exit off to the east this afternoon.
Southerly flow should pick up this afternoon with wind gusts up
to 30 mph possible across western New York. A warm frontal
segment is advertised to cross the region which may introduce a
shower or an isolated thunderstorm. Continuing to watch as dying
upstream MCS makes its way eastward. Latest CAMs trying to hold
onto some of this convection as it shifts into western New York
after 18z. Would expect that if some of this convection does
manage to hold together it will be in a much weaker state.
Otherwise, highs today will be mainly in the lower 80s, with the
warmer spots in the mid to upper 80s.

A cold front drops south into the region tonight with additional
chances for some showers or a isolated thunderstorm. The best
chances will again be found again across the North Country closer to
the support from the upper-level jet. Overnight low temperatures
should fall back into the 60s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
On Wednesday low pressure over northern Quebec and Labrador will
gradually pivot its trailing cold front southeastward across
our area. During the morning and very early afternoon hours...this
feature should be largely starved for much in the way of
support...and thus will probably only produce some scattered
showers and perhaps a couple of thunderstorms as it makes its
way roughly to/ just south of the I-90 corridor. After that
time...a wave of low pressure will ripple northeastward along
the boundary and slow its southward progress through the balance
of the day...while also providing a notable uptick in moisture
and large-scale ascent. This should translate into showers and
some storms becoming more numerous to widespread across the
Southern Tier and interior of the Finger Lakes Region during the
afternoon and early evening hours...while more scattered pcpn
should be found further north along the northern periphery of
the passing wave. Given continued uncertainty in the
timing/positioning of the frontal boundary...the amount of
available instability during this more active portion of
Wednesday remains rather questionable at this time. This being
said...if sufficient instability is realized can see at least a
lower-end risk for an isolated stronger storm or two across the
Southern Tier given the presence of sufficient shear...which
lines up well with the Marginal Risk for severe storms
advertised by SPC in the latest Day 2 Convective Outlook. With
PWATs also temporarily surging to around 1.5 inches...there will
also be at least some threat for heavy rainfall with any
storms...with this risk again greatest across the western
Southern Tier which will lie closest to the track of the passing
wave. With respect to temperatures...these should range from
the mid 70s to lower 80s...with humid conditions out ahead of
the front becoming somewhat less so following the passage of the
boundary.

Wednesday night a shortwave trough will slide across our region
while escorting the initial wavy cold frontal boundary and any
deeper moisture/attendant threat for heavier rain off to our south
and east...resulting in a commensurate northwest-to-southeast
decrease in pcpn potential. In its wake...a much weaker and moisture-
starved secondary cold front will slide across our area later
Wednesday night and early Thursday...while possibly bringing a few
more widely scattered showers to the North Country and far eastern
Finger Lakes. Yet another shortwave will then dive across Southern
Ontario and Saint Lawrence Valley Thursday afternoon and evening...
and this in tandem with some weak diurnally-driven instability could
lead to a yet few more widely scattered showers across the North
Country. Otherwise generally dry and uneventful weather will
predominate across our region from the second half of Wednesday
night through Thursday...though the influx of cooler air and
developing upslope flow behind the passing fronts will probably lead
to at least some lower clouds hanging around into Thursday morning.
As for temps...the incoming cooler/drier airmass will bring about
much more comfortable conditions for Wednesday night and Thursday...
with lows Wednesday night generally between 55 and 60...and highs on
Thursday mostly ranging from the upper 60s across the higher terrain
to the lower 70s elsewhere.

Expansive Canadian high pressure will then build directly across our
area Thursday night...then will drift east into New England on
Friday. This will provide us with fair dry weather to close out the
work week. Excellent conditions for radiational cooling will allow
lows to settle into the mid-upper 40s across the interior Southern
Tier/North Country and to the lower-mid 50s elsewhere Thursday
night...with a developing southerly return flow on the backside of
the departing ridge then allowing highs to recover to the mid 70s
across the North Country and the upper 70s-lower 80s elsewhere on
Friday.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
-- Changed Discussion --
A well defined shortwave trough will cross the Great Lakes Saturday,
deepening an area of surface low pressure that will advance from the
northern Great Lakes through southern Quebec Saturday. A deep
southerly flow ahead of this trough will advance moisture northward,
increasing PWATs to nearly 2 inches across the eastern Great Lakes
region. Showers and thunderstorms are expected to form Saturday and
continue through the evening hours of Saturday before a cold front
crosses the region from west to east late. The timing of the cold
front, cloud cover holding instability back to around 750 J/KG or
less and poor mid level lapse rates under 6 C/KM are not favorable
for strong to severe storms. However, 0-6 km bulk wind shear values
35 to 45 kts could aid in strength to the storm if any taller storms
can develop.

Behind the cold front a much drier airmass will settle upon the
eastern Great Lakes. We`ll still have to contend with a few showers
Sunday with the passage of the upper level trough, but drier air and
eventually cooler airmass (mid single digit Celsius 850 hPa
temperatures) will bring a cool night Sunday night with lows in the
mid 40s to mid 50s. Fair weather Monday, with comfortable dewpoints
in the 40s and 50s with high pressure nearby. Tuesday a return
southerly flow along with the approach of a shortwave from the west
may trigger a few showers or thunderstorms.
-- End Changed Discussion --

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Mainly VFR expected to remain across all area terminals today. South
to southwest winds pick up today across far western terminals to
include KBUF, KIAG, and KJHW. Winds up to 30 knots will be possible.
There is also the chance of some showers as remnants of the upstream
MCS crosses the region. With it...ceilings will begin to lower, with
some MVFR Cigs by this evening.

Tonight...a mix of VFR/MVFR Cigs will be found across most area
terminals. Lower Cigs (IFR) may materialize across the S. Tier to
include KJHW, along with some patchy fog producing lower vsbys.

Outlook...

Wednesday...MVFR/VFR with a chance for showers most area terminals.
Showers and a chance of thunderstorm across the Southern Tier.
Thursday and Friday...Mainly VFR.
Saturday...Localized restrictions with shower likely and a chance of
thunderstorms.

&&

.MARINE...
A south to southwest wind flow picks up across Lake Erie and the
western end of Lake Ontario today. Waves will be offshore, but a
period of Small Craft conditions will develop this afternoon into
the evening. SCAs remain in effect for Lake Erie beginning at 16Z
though 03Z this evening. There will also be a chance of some
showers, this as a pair of fronts cross the region through tonight.
Winds will also remain elevated on area lakes tonight producing
light to moderate chop on both lakes.

Lighter winds and wave action is expected Wednesday but there may be
better coverage of shower and storm for Lake Erie.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
         Small Craft Advisory until 11 PM EDT this evening for
         LEZ040-041.
-- End Changed Discussion --

&&

$$

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