064
FXUS61 KBUF 221520
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1120 AM EDT Sun Sep 22 2024

.SYNOPSIS...
A narrow ridge of high pressure will bring a dry day for most areas,
with a mix of clouds and sunshine through yet another warm day. A
cold front will near the region late tonight and Monday, bringing
showers and an isolated rumble of thunder to again primarily Western
New York. As a warm front lifts across the region Tuesday night and
Wednesday more widespread rain showers will fall upon the entire
region.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today will feature a mix of sun and clouds with dry weather
prevailing...as a narrow ridge will build across the Lower Great
Lakes. A southeast flow through the day will meet developing lake
breeze boundaries with perhaps a spot shower for inland areas of
Western New York. However most areas should remain dry through the
day. Temperatures will remain above normal with most highs in the mid
70s to around 80.

Dry through the evening and much of the overnight hours. It will
remain warm with a light southerly flow ahead of a cold front that
will approach from the west. As moisture increases aloft, and a
shortwave trough reaches WNY, clusters of light showers ahead
of this cold front will move into far western locations late
tonight.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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.

Tuesday through Tuesday night, a northern stream trough will dig
into the Upper Midwest, carving out a deep longwave trough over the
upper Mississippi Valley and western Great Lakes. The digging
upstream trough and associated downstream flow adjustments will
force a southern stream shortwave and a substantial area of deep
moisture to move northeast from the Ohio Valley into the eastern
Great Lakes later Tuesday through Tuesday night. Tuesday may start
mainly dry in Western NY, but rain chances will then increase
through the day as deep moisture and forcing increase with the
approach of the southern stream shortwave. Farther east, expect dry
time to last longer through the day Tuesday, with rain arriving in
the eastern Lake Ontario region later in the afternoon or evening.
Rain will be widespread Tuesday night as the best forcing and
deepest moisture cross the region. There could be some isolated
thunder later Tuesday through Tuesday night with limited
instability, but expect coverage to remain sparse.

Temperatures will trend downward through the first half of the week
with persistent clouds, showers, and a somewhat cooler airmass.
Highs Monday and Tuesday will be in the lower 70s for lower
elevations and 60s for higher terrain, but it will be cooler than
that during periods of rainfall.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A deep longwave trough over eastern North America on Wednesday will
advance slowly east to the eastern seaboard through the end of the
week. While this general large scale pattern is well agreed upon in
model and ensemble guidance, the smaller scale details have shown
considerable run to run differences, especially in the handling of a
potential closed low over the south central US late in the week.

For our area, the slow eastward progress of the longwave trough will
keep unsettled weather in the forecast with a good chance of rain
showers Wednesday through at least Thursday. The finer scale
synoptic details that are quite uncertain at this point will
determine how widespread the rain will be on these days. The rain
chances will gradually taper off from west to east Friday through
Saturday as the trough moves slowly east, and the plume of deeper
moisture moves to along, and eventually off the east coast.

Temperatures will continue to run cooler than the past few weeks.
Highs most days will be in the lower 70s for lower elevations and
60s for higher terrain, but it will be cooler than these values
during periods of rain.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
While there will still be some MVFR conditions in stratus over the
IAG Frontier into the midday hours...high pressure will support VFR
conditions through this evening.

While cigs will lower tonight with some showers developing over the
far western counties by daybreak...VFR weather can be expected.

Outlook...

Monday through Thursday...VFR/MVFR with chance to likely showers and
a chance of thunderstorms at times.

&&

.MARINE...
A weak ridge of high pressure will maintain light winds and low wave
heights on the Lakes today. There may be a little fog over the
western Lake Ontario waters through the morning and early afternoon
hours.

Tonight winds will become southeasterly ahead of a cold front. 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.

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.

&&

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

&&

$$

SYNOPSIS...Thomas
NEAR TERM...Thomas
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...RSH
MARINE...Thomas