931
FXUS61 KBUF 240457
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1257 AM EDT Tue Sep 24 2024

.SYNOPSIS...
As a mid-level disturbance departs the region, a few rain showers
will linger through the nighttime hours. An approaching and crossing
warm front will bring a round of widespread rain showers Tuesday
afternoon and night. A cold front may keep some showers into
Wednesday. Temperatures will trend above normal through mid week.

&&

.NEAR TERM /THROUGH TODAY/...
Weak surface low pressure over Lake Erie will degrade into an
inverted surface trough tonight, while an associated surface
boundary remains situated near or just west of BUF/IAG. Cloud cover
will linger through the night, with a few mainly light showers with
overall weak forcing. The majority of the scattered showers will
focus along a convergence zone from Allegany County northward to
areas just west of the Genesee River.

Low temperatures tonight will range from the lower 50s on the Tug
Hill, to mid 50s to lower 60s across the lake plains of Western NY
with persistent southeast downslope flow.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
A deep longwave trough will advance from the Mississippi Valley
Tuesday towards the Great Lakes and Ohio Valley by Wednesday. Models
are in decent agreement that the large-scale trough will evolve
separate northern and southern stream components, with a closed
cutoff low developing near the Ohio-Mississippi River confluence,
and a negative tilt trough and/or closed low develop across eastern
Ontario into Quebec by Thursday morning.

Tuesday morning will be mainly dry, with a few isolated showers at
most across the region.  However, during the afternoon, a shortwave
embedded in the developing northern portion of the large scale
trough will cross the Great Lakes and surface low pressure will lift
into lower Michigan by Tuesday night. With lift supported by the
shortwave and a surface warm front, and strengthening southwest flow
bringing precipitable water values in the 1.5 to 1.6 inch range by
Tuesday evening, widespread showers appear to be a good bet later
Tuesday and Tuesday night.

On Wednesday, as the Michigan surface low lifts into Quebec, the
system cold front will be dragged across the eastern Lakes and
reside in the eastern portions of the forecast area by afternoon. A
weak wave along the boundary may keep higher PoPs going here, while
drier air tries to build in behind the boundary in western New York,
leading to a drier forecast. This drier air becomes more widespread
across the region by Thursday as the northern shortwave trough axis
shifts more towards New England, although a few showers may continue
in the eastern Lake Ontario region, closest to sufficient moisture
and forcing.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Dry weather appears likely through at least the Thursday night
through Saturday period.  A ridge appears likely to set up in the
western New York area between upper level low pressure across the
Canadian Maritimes, and another upper low centered somewhere in or
near the Lower Mississippi Valley.  The only fly in the ointment
could be related to this week`s potential Gulf tropical activity, as
a small bit of moisture from what would be remnants at that
point could sneak into areas south and west of Buffalo on
Saturday, producing some showers.

Uncertainty regarding the Mississippi Valley upper low increases
thereafter according to model cluster analysis, with the slight
majority of scenarios keeping the low center more or less in place,
while others try to open the system and eject it to the northeast.
This latter scenario would lead to a wetter forecast for western New
York by the end of the forecast period. Given this uncertainty, the
NBM idea of some low PoPs across areas generally near and west of I-
390 during the Sunday/Monday period is a good one. Temperatures will
continue run a little above normal overall.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Scattered showers will continue through the early morning hours,
especially just west of the Genesee Valley. CIGS across Western NY
will continue to run mainly MVFR for lower elevations and IFR across
the higher terrain of the western Southern Tier through the morning
hours. Meanwhile, areas east of Lake Ontario will stay dry with VFR
CIGS.

Surface low pressure and a strong upper level system will move from
near Lake Michigan this morning northeast across the central and
eastern Great Lakes later today through tonight. A broad area of
ascent ahead of this system will bring another round of widespread
rain showers, entering Western NY midday to mid afternoon, then
spreading east across the rest of the area later this afternoon
through tonight. Pockets of moderate rain may bring a few periods of
lower VSBY.

Expect widespread MVFR/IFR CIGS across Western NY this afternoon,
spreading east across the remainder of the area tonight. IFR will be
favored across higher elevations. S/SE downslope flow will try to
hold the CIGS higher across the lake plains including most of the
terminals. MVFR CIGS are still likely, but the downslope flow may
help to keep IFR at bay this afternoon through tonight.

Outlook...

Wednesday...MVFR/IFR with showers likely. A few widely scattered
thunderstorms possible.

Thursday...MVFR east of Lake Ontario with a chance of showers.
Becoming mainly VFR elsewhere.

Friday through Saturday...Mainly VFR. Local IFR in valley fog
across the Southern Tier each overnight and morning.

&&

.MARINE...
Southeast wind will continue through tonight, approaching 20
knots over the offshore waters of eastern Lake Ontario. Waves of
3 to 5 feet can be expected here along the Canadian border
waters.

South to southeast wind will continue into Wednesday as a
cold front stalls over the lower Great Lakes. Once this front
passes on Wednesday, winds will veer through southwest and to a
westerly direction during the Wednesday night/Thursday period.

&&

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

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...HSK
LONG TERM...HSK
AVIATION...Hitchcock
MARINE...Hitchcock