900
FXUS61 KBUF 251808
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
208 PM 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 THURSDAY NIGHT/...
It will be damp and unsettled tonight...as a storm system pushing
north from Georgian Bay will drag a wavy cold front through our
region. In advance of this sfc front...a slug of deep moisture (PWAT
1.5") will be lifted by a combination of a 110kt H25 jet rotating
around the base of a vigorous northern stream shortwave and
convergence in the lower levels. This will result in fairly
widespread showers...some of which could be locally heavy. Rainfall
amounts tonight are forecast to range from a quarter to a half inch
in most basins...with the lesser amounts expected to be over the
Finger Lakes region. Elevated CAPE of 200-400 j/kg will be found
within this environment...so will maintain the chance for
thunderstorms. While the showers will taper off from west to east
late tonight as the mid level moisture gets stripped away...a wealth
of cloud cover will persist.

The slow moving front will certainly take its time exiting the
Eastern Lake Ontario Thursday morning...so likely to cat pops will
remain in place for the initial daylight hours. Meanwhile...s l o w
clearing will start to take place back across the IAG Frontier. As
we push through the midday and afternoon...the residual showers will
come to an end with more pronounced clearing taking place further
west due to more effective diurnal mixing and strengthening
subsidence from sfc based ridging.

High pressure centered to the north of Lake Ontario Thursday night
will then guarantee fair dry weather...although some cloudiness may
still linger near the Pennsylvania border. It will be notably
cooler...with mins forecast to be in the low to mid 50s...rather
than the 60s from the previous two nights.

&&

.SHORT TERM /FRIDAY/...
Friday...the Lower 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 with
highs in the low to mid 70s for lower elevations and upper 60s
for higher terrain.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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 /18Z WEDNESDAY THROUGH MONDAY/...
A slow moving cold front will produce fairly widespread showers
throughout the region tonight...with most areas experiencing MVFR to
IFR cigs...the latter of which will be focused across the Srn Tier.

While showers will persist east of Rochester Thursday morning...fair
dry weather will return to the region. Cigs will improve to VFR
levels by late morning/midday...then most areas will lose their cigs
altogether by the end of the day.

Outlook...

Thursday night...Mainly VFR.
Friday...Mainly VFR...but with a chance of showers across the
western Southern Tier.
Saturday through Monday...VFR.

&&

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