241
FXUS61 KBUF 090459
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1259 AM EDT Sun Jun 9 2024

.SYNOPSIS...
A trough will cross the region tonight with a period of rain
overnight. Unsettled weather will continue Sunday through Monday
with a few showers and cool temperatures before drier and warmer
weather returns by the middle of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A mid level trough and associated forcing will continue to support
an area of widespread light to moderate rain crossing the region
overnight. Removed the thunder from the forecast as currently there
are no lightning strikes, and not till tomorrow will instability
increase.

Supporting lift will an upper level jet streak on the southern flank
of the trough that will strengthen overnight, with a commensurate
increase in upper level divergence as the left exit region and
associated thermally indirect ageostrophic circulation of the jet
crosses the eastern Great Lakes overnight.

The steady rain will be done by Sunday morning at most locations,
except east of Lake Ontario where it will linger through around mid
morning. The leading edge of the shortwave and associated PVA will
exit into New England Sunday, but a secondary mid-level trough axis
will drop southward across the region Sunday afternoon. This will
bring the risk of more showers, and possibly a thunderstorm. A west
to east line of storms is likely to form, within this trough as well
as on a low level convergent wind flow boundary. This line will drop
southward across metro Buffalo, Batavia and the Genesee Valley with
downpours of rain. Temperatures will remain below normal with highs
mainly in the mid to upper 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A slow moving mid-level trough and low over Southeast Canada & the
Northeast to start the period will provide the continued opportunity
for showers and some thunderstorms into the early afternoon on
Monday. Shower potential will increase at times as a few different
shortwave troughs track through the larger trough. The combination
of the forcing from the troughs along with synoptic moisture in
place will bring a round of showers with some embedded thunderstorms
to the region Sunday night into Monday morning. Cooler temperatures
aloft of around 5C moving over the warmer lake waters which are
around 15 to 17C will also help aid in some increased instability
within areas of showers with the passing troughs.

Sunday night, best potential for showers will be early on in the
evening and later in the overnight with somewhat of a break between
two passing shortwave troughs. Evening showers may have a few
embedded thunderstorms with earlier daytime heating still providing
some instability. Rainfall amounts should generally remain below a
tenth of an inch for the night.

Monday, a shortwave trough axis will drop southeast across the area
around the time of the morning commute, causing a batch of showers
to move through. As the trough axis tracks out of the area, showers
will taper off from northwest to southeast through the morning and
into the early afternoon. Showers will linger the longest south of
Lake Ontario where the combination of upsloping, daytime heating and
instability/moisture from the warmer lakes will help prolong showers
for a few additional hours. A few embedded thunderstorms will be
possible once again for Monday as well. Rainfall on Monday should be
limited to a tenth of an inch for most areas, but a few higher
amounts within any heavier showers will be possible.

Monday night through Tuesday night, any lingering showers later
Monday afternoon will dissipate or move out of the area. A sharp
ridge will track toward the area on Monday evening pushing drier air
into the region while also increasing heights. The ridge axis will
center over the region on Tuesday, resulting in fair dry weather
through at least Tuesday night.

Temperatures for the period will be below normal for both Monday and
Tuesday afternoon, with Monday`s max temperatures around 10 degrees
below normal for most areas. A notable warmup for Tuesday will bring
temperatures closer to, but still below normal with highs in the mid
60s to low 70s. Nightly lows will be closer, but still mostly below
normal for all three nights, with Monday night being the coolest as
the ridge moves in but warm air advection doesn`t start to increase
temperatures yet.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
On Wednesday deep-layer ridging draped across New York State at the
start of the day will slide east into New England and flatten a
bit...while a shortwave trough pivots across the Upper Great Lakes
and central Ontario. The slowly departing ridge will maintain enough
of a grip upon our region to bring us another dry day along with
seasonably warm highs in the mid 70s to around 80...though a
southwesterly flow will help to keep the northeastern shores of
Lakes Erie and Ontario a bit cooler.

Wednesday night and early Thursday the aforementioned shortwave
trough will slide by to our north. Cannot rule out a stray shower
along our northern periphery attendant to this feature`s passage...
however this should largely just produce a temporary increase in
cloud cover. Immediately behind this the GFS attempts to bring a
convectively-induced wave and associated pcpn directly across our
region during the course of Thursday...however this looks overdone
and is also a marked outlier compared to the other medium-range
guidance. Have therefore discounted this solution in favor of a
continued mainly dry forecast through Thursday...with just an
isolated pop-up shower or two possible during the afternoon with
diurnal heating. Otherwise Thursday should be a bit warmer...with
highs ranging from the upper 70s across the higher terrain to the
lower to mid 80s across the lower elevations...though it will again
be cooler immediately northeast of the lakes.

Thursday night and Friday the next mid-level trough will dig across
the Great Lakes and Northeast...with an associated cold front
sliding across our region during Friday. This should bring us a
round of scattered convection...followed by a return to drier
weather Friday night and Saturday as surface high pressure and drier
air builds in behind this system. As for temperatures...highs on
Friday will be very similar to those of Thursday...before pulling
back a little into the mid 70s to around 80 for Saturday.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A mid level trough and frontal wave will continue to support an area
of widespread light to moderate rain crossing the region from west
to east overnight. The pockets of moderate rain will bring reduced
VSBY at times. Initial VFR CIGS will deteriorate to MVFR and spotty
IFR towards the tail end of the rain early this morning as the low
levels saturate.

The lower CIGS early this morning will mostly scatter out by late
morning, and there will be a brief break in the rain following the
early morning exit of the widespread rain from the frontal wave.
Midday into the afternoon, another mid level trough and surface cold
front will move southeast across the area, and combine with modest
daytime instability and lake/terrain generated low level convergence
boundaries to generate another area of showers and scattered
thunderstorms crossing the area from northwest to southeast. Expect
areas of MVFR CIGS/VSBY to develop, with local/brief IFR in
thunderstorms.

The more organized showers and scattered thunderstorms will taper
off this evening, although a few scattered showers may linger
overnight. CIGS/VSBY should improve back to VFR initially in the
evening, but areas of MVFR CIGS will likely develop overnight in
stratus.

Outlook...

Monday...Areas of MVFR with scattered showers.
Tuesday through Thursday...Mainly VFR.

&&

.MARINE...
As westerly winds back off temporarily tonight, all that is left
of the small crafts are along the eastern shoreline of Lake
Ontario. These winds will ramp up again Sunday with another
round of Small Craft Advisory conditions on both lakes. Also, a
weak surface wave of low pressure passing by to the south this
evening will cause winds to temporarily shift to the northeast
on Lake Erie, and these winds may pick up to close to small
craft criteria few a few hours.

Winds will come down some Sunday night through Monday, but will
still be strong enough to produce choppy conditions on both lakes.
More favorable winds and waves for boating will return by the middle
of next week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement through this afternoon for NYZ005>007.
MARINE...Small Craft Advisory until 2 AM EDT early this morning for
         LOZ044-045.

&&

$$

SYNOPSIS...Apffel/Hitchcock
NEAR TERM...Apffel/Hitchcock/Thomas
SHORT TERM...SW
LONG TERM...JJR
AVIATION...Hitchcock
MARINE...Apffel/Hitchcock