-- Discussion containing changed information from previous version are highlighted. --
115
FXUS61 KBUF 230553
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
153 AM EDT Mon Sep 23 2024

.SYNOPSIS...
-- Changed Discussion --
A mid level disturbance will cross the Lower Great Lakes today,
bringing widespread showers to Western New York, with activity more
scattered east of Lake Ontario. Cloudy skies today will promote
temperatures much closer to early autumn normal. As a warm front
pushes across our region Tuesday night and Wednesday more widespread
rainfall will occur across the entire region.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TODAY/...
An approaching wavy frontal boundary will spread some showers across
the western counties after midnight. It will remain mild tonight
with mins ranging from the lower 60s in most areas...to near 50 in
the vcnty of the Tug Hill.

Monday, a mid level shortwave and associated surface trough will
move east across the eastern Great Lakes, weakening with time and
eastern extent. Showers will have spread into much of Western NY
from the Genesee Valley westward by daybreak Monday with the arrival
of deeper moisture and forcing. The showers will then spread east
through the day, reaching Central NY and the eastern Lake Ontario
region by afternoon. The coverage and intensity of showers will
likely diminish with eastern extent as forcing weakens. Meanwhile
across Western NY, expect some dry time to develop Monday afternoon
in the wake of this first trough as a mid level dry slot moves into
the area.

Monday night, the initial mid level and surface trough will continue
to weaken and wash out over Central NY and the eastern Lake Ontario
region as it moves into a persistent ridge and subsidence over the
northeast US. An area of mid level dry air will move into the
eastern Great Lakes, supporting a temporary lull in rain. Low level
moisture will persist, so a few isolated light showers cannot be
ruled out, but expect it to be rain free much of the time Monday
night.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Tuesday, a northern stream trough will gradually dig into the Upper
Midwest, eventually carving out a deep longwave trough over the
Quebec by Wednesday night. Chances for showers will increase during
the day Tuesday as the trough gets closer and as a diffluent flow
aloft and favorable jet dynamics push eastward into Western NY. This
combined with a modest 30kt LLJ at 850mb will advect deeper moisture
which will support widespread showers by Tuesday night. The axis of
best synoptic support will shift to the Genesee River valley
eastward Wednesday, and then into western New England Wednesday
night and Thursday. By Thursday models are coming into better
agreement with only small chances for some lingering scattered
showers. Instability will be limited, but ample to support a few
thunderstorms at times, especially during the afternoon and
evening hours Tuesday and Wednesday.

Despite the high confidence in measurable showers, there will be
periods of rain-free time. Rainfall amounts will vary, but the
system will bring needed rainfall to many locations with event
totals averaging in the half inch to inch range from Tuesday through
Thursday. Locally heavier rains cannot be ruled out, with WPC
placing Western NY in a marginal risk for excessive rainfall Tuesday
and Tuesday night. This is mainly due to slow storm motion and
precipitable water values around 1.5 inches.

The system will also bring cooler temperatures, especially during
the daytime when highs will range from the lower 60s to mid 70s.
Cloud cover and a southerly flow will keep temperatures from cooling
much overnight, with the overall cooler pattern still only resulting
in near normal temperatures for late September.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Models are in good agreement that ridging at the surface and aloft
will develop across our region during the period. This will suppress
whatever tropical disturbance develops in the Gulf of Mexico next
week, keeping any associated precipitation to our south. Rain-free
and warm weather will prevail through next weekend, with high
temperatures in the 70s.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
For the 06Z TAFS light rain showers are pushing their way into far
WNY, with VFR ceiling heights. This activity will slowly push
eastward the next 12 hours before weakening and fading over CNY this
late afternoon and early evening. There is a much lower probability
of these showers reaching KART.

Southeast flow ahead of a cold front this forecast period...with
this cold front remaining just to our west.

Ceiling heights will lower as moisture in the lower levels
increases...with MVFR (and higher terrain IFR) ceiling heights by
roughly 12Z for WNY...with these widespread MVFR ceiling heights
expected through the remainder of the TAF period for WNY. IF this
southeast flow becomes a little stronger, downslope flow will lift
these ceilings for KBUF/KIAG and KROC to low end VFR.

VFR, or high end MVFR may linger east of Lake Ontario where moisture
will not be as deep.

Tonight will be mainly dry, though a few isolated rain showers
cannot be ruled out.

Outlook...

Tuesday...IFR to MVFR cigs over the western counties in scattered
showers and thunderstorms, but mainly VFR and dry east of Lake
Ontario.
Wednesday...IFR to lower end MVFR regionwide with the likelihood of
more showers and thunderstorms.
Thursday...MVFR with scattered showers...mainly east of Lake
Ontario.
Friday...VFR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Winds will be from the southeast today and tonight. These southeast
winds will approach 20 knots over the offshore waters of eastern
Lake Ontario...with waves around four to five feet rolling into the
Canadian waters today.

This cold front will stall just to the west of the Lower Great
Lakes, with a south to southeast flow maintained over the Lake
waters through Wednesday. Eventually this cold front will push
eastward, with winds veering to a westerly flow Wednesday night and
Thursday.
-- End Changed Discussion --

&&

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

&&

$$

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