865
FXUS61 KBUF 251138
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
738 AM EDT Wed Sep 25 2024

.SYNOPSIS...
Weak low pressure tracking by to our west and north today will drag
a wavy cold front through the region tonight. While scattered
showers will be found ahead of this front today...heavier...more
widespread showers can be expected tonight. Areas east of Rochester
may experience some left over showers Thursday morning...otherwise
high pressure will build across the Lower Great Lakes to support
fair dry weather Thursday afternoon through at least Friday. Most...
if not all...of the significant rains from Helene should stay to
our south.

&&

.NEAR TERM /THROUGH TONIGHT/...
Regional radar shows some showers across the forecast area this
morning. Drier air is moving into the forecast area as evident
on water vapor imagery. Showers will mainly be confined to the
northern tier of the forecast area this morning, however a few
showers are possible  across western NY, in vicinity of a warm
front.

A strong ridge is centered over the Intermountain West as a trough
digs into the Mid-West and Ohio Valley this morning. A steady state
area of low pressure over northern Michigan will move north-
northeast today. Organized Showers have mainly moved into the
Saint Lawrence Valley this morning as a low level jet exits to
the northeast. A warm front will continue to lift northward from
northwest Pennsylvania and move into far western NY this
morning. Additional showers may blossom through daybreak.
Elsewhere, mostly dry conditions expected as drier air moves
into the forecast area this morning. A humid airmass (for late
September standards) will draw dewpoints into the low 60s across
the forecast area. The combination of daytime heating in a
moist airmass and upper level diffluence ahead of the trough
will likely result in showers developing this afternoon.
Forecast soundings show a well saturated column with weak
instability, however with theta-e advection during peak heating,
can`t rule out a few thunderstorms.

The trough will move east while the low drags a cold front towards
the forecast area this evening. Showers will expand in coverage
tonight with the potential for moderate to heavy showers east of the
Genesee Valley after midnight. Drier air will filter into the west
behind the cold front but low level moisture will linger. Clouds
will start to clear across the Niagara Frontier by daybreak Thursday.

Rainfall amounts will vary across the forecast area today and
tonight. Amounts will mainly average less than 0.10 inches, however
far western NY and the north central NY will average 0.10-0.25
inches today. Rainfall amounts will average 0.25-0.50 inches
tonight, however any thunderstorms could produce amounts of up to an
inch, mainly near Lake Erie and north central NY.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
A sharp mid level trough will move from near the Ontario/Quebec
border Thursday morning to eastern Quebec and northern New England
by late Thursday night. An associated surface cold front will cross
the region Thursday morning. Latest 00Z model guidance has slowed
the eastward progression of the front by a few hours, which brings
a little more rain into the forecast for Thursday morning. Expect
showers to end in far Western NY around daybreak Thursday, with rain
and possibly a few isolated thunderstorms lasting through the
morning for areas east and southeast of Lake Ontario before ending
in the afternoon. A notable mid level dry slot will quickly follow
the surface cold front, allowing for sunshine to return later in the
day from northwest to southeast.

Thursday night through Friday the eastern Great Lakes will be in a
squeeze play between an evolving mid level low over northern New
England and the Canadian Maritimes, and another closed low over the
south central US. Between these two large systems, a narrow ridge of
high pressure surface and aloft will build over the Great Lakes and
support dry weather for our region.

Temperatures will continue to run a little above average Thursday
through Friday, with highs in the low to mid 70s for lower
elevations and upper 60s for higher terrain.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A complex pattern will evolve over the eastern US Friday night
through the weekend. A mid level low over the Canadian Maritimes
will move slowly southeast and into the North Atlantic Friday night
through Saturday. Meanwhile, another large mid level closed low over
the south central US will interact with the remnants of Helene Friday
through Friday night, with a classic Fujiwhara interaction as the
remnants of Helene first move in a cyclonic loop around the mid
latitude closed low, and then eventually become absorbed into the
closed low by Saturday over the Tennessee Valley.

The vast majority of the greater impacts with the closed low and
remnants of Helene will remain well southwest of our area across the
Ohio Valley. Expect an extensive shield of mid/high clouds to stream
northward into the eastern Great Lakes later Friday through the
weekend as the upper level outflow of Helene`s remnants spread
northward. Latest model guidance suggests the northern extent of
light showers wrapping around the system may clip the western
Southern Tier later Friday night through Saturday, with mainly dry
weather elsewhere.

Sunday through Monday, model and ensemble guidance show the mid
level low containing the remnants of Helene moving east across the
Ohio Valley to the Mid Atlantic states. This track would keep the
majority of the rain south of our region, but it would not take much
of a northward shift to bring higher rain chances to our area and
this will need to be monitored through the coming days.

Tuesday, a strong mid level trough and associated cold front is
forecast to dig southeast across the Great Lakes, bringing an
increasing chance of showers. The airmass is quite cool behind this
cold front, with a trend towards below average temperatures for at
least a few days starting around the middle of next week.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Low pressure will move northwest of the region today. Showers will
move across the Lake Ontario region including north central NY
this morning. Drier air will enter western NY decreasing the
chance for showers through mid-morning. A warm front is in
vicinity of northwest Pennsylvania which may result in a few
showers developing across far western NY this morning.

A southeast flow has resulted in mainly VFR conditions across
the lower elevations with the exception of any showers or
thunderstorms this morning. Low clouds/fog will hang onto the hill
tops across the region and result in sub-VFR, mainly IFR conditions
at KJHW/KOLE. Flight conditions do not change much through the day
with MVFR/low end VFR across most of the TAF sites and IFR at KJHW.
Showers and a few thunderstorms will likely develop this afternoon.
These may result in brief periods of IFR at the TAF sites. A cold
front will move across the region this evening. Heavier showers and
a few thunderstorms will move through the region. MVFR/IFR
conditions will linger into Thursday morning.

Outlook...

Thursday...MVFR east of Lake Ontario with a chance of showers.
Becoming mainly VFR elsewhere.
Friday through Sunday...Mainly VFR. Local IFR in valley fog
across the Southern Tier possible overnight into the morning.

&&

.MARINE...
A moderate pressure gradient will remain in place over the eastern
Great Lakes today through tonight between persistent high
pressure over the Canadian Maritimes and low pressure moving
through the central Great Lakes. This will maintain moderate
southeasterly flow today, with the strongest winds on the east
half of Lake Ontario today. The southeast wind direction will
continue to push the greater wave action into Canadian waters,
but the offshore winds will become strong enough to require a
Small Craft advisory for the eastern ends of Lake Ontario and
Lake Erie.

Winds will gradually become southwest and then west tonight through
Thursday as a trough crosses the eastern Great Lakes from west to
east, with wind speeds decreasing with the passage of the trough.
Northeast flow will then pick up Friday, possibly requiring small
craft headlines on Lake Erie and western Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 2 AM EDT Thursday for LOZ045.

&&

$$

SYNOPSIS...RSH
NEAR TERM...HSK
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...HSK
MARINE...Apffel/Hitchcock/HSK