838
FXUS61 KBUF 251828
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
228 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 /THROUGH WEDNESDAY/...
Surface ridge will continue to exit off to the east through this
afternoon. Strengthening southerly flow bringing wind gusts up to 40
mph this afternoon across far western New York. Earlier MCS has
nearly fall apart with some remnant showers moving across southern
Ontario/Lake Ontario. Some of this shower activity could brush the
eastern Lake Ontario region later this afternoon.

A weak 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.

Wednesday should start off relatively quietly as the frontal
boundary working south overnight stalls out over the region. This
boundary waver back northward during the day as a frontal wave moves
north along it from the Ohio Valley. The western Southern Tier will
have the best chance to emerge into the warm sector, with the
potential that the warm sector lifts as far north as the I-90
corridor by afternoon. The coverage of thunderstorms and the
potential for severe weather will depend greatly on the position of
the frontal boundary with the degree of instability high depended
upon where the warm sector is located. Therefore, CAPE values remain
in question, but sufficient shear looks to be present, especially
along the Southern Tier, which lines up with the Marginal Risk for
severe storms maintained by the latest SPC Day 2 Convective Outlook.
Precipitable water values surge to near 1.5 inches bringing at least
some threat for heavy rainfall. The greatest risk of this will be
across the western Southern Tier which will lie closer to the track
of the passing frontal wave.

&&

.SHORT TERM /WEDNESDAY NIGHT 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/...
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.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Mainly VFR expected to remain across all area terminals into this
evening. South to southwest winds of 30 to 35 knots at KBUF and KIAG
and possibly KROC will diminish after 00Z.

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.

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.
Sunday...Mainly VFR.

&&

.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 and for the Upper Niagara River until 00z.
Winds will remain elevated on area the lower Great Lakes tonight
producing light to moderate chop on both lakes.

Lighter winds and wave action is expected Wednesday but there will
be a better coverage of thunderstorms for Lake Erie.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
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.

&&

$$

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