417
FXUS61 KBUF 120047
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
847 PM EDT Sat May 11 2024

.SYNOPSIS...
A weak area of low pressure will slowly cross our region tonight,
resulting in widespread showers and possibly a few evening
thunderstorms. The precipitation will gradually taper off during the
day Sunday as weak high pressure noses into the area. While
noticeably warmer weather will move in for Monday, it will also once
again become unsettled with increasingly widespread showers and
thunderstorms that will persist into Tuesday.

&&

.NEAR TERM /THROUGH TODAY/...
A robust shortwave and attendant surface low will continue to slowly
cross southwestern Ontario Province this evening. A swath of deep
moisture ahead of this system that has been producing widespread
showers across western NY, is now slowly pushing northeast into the
eastern Lake Ontario region as evident by northeastern edge of
shower activity now starting to blossom over Oswego County and will
continue to push across the eastern Lake Ontario region through the
early overnight hours.

The area of low pressure will then slowly push across the forecast
area overnight. While the bulk of the associated showers and
isolated thunderstorms will be found along and immediately ahead of
an attendant occlusion in the area of strongest low level
convergence, the precipitation will tend to broaden out during the
course of the night. By the time we work past midnight, the showers
will tend to give way to areas of light rain with some patchy fog,
mainly under the stacked low itself. Rainfall amounts will generally
range from a tenth to a quarter inch, although localized amounts of
a half inch will be possible in the vicinity of any evening
thunderstorm. Lows tonight will range from the low 40s across the
higher terrain to the mid and upper 40s elsewhere.

The stacked low will further weaken on Sunday with its mid level
support briefly `opening up` enough to allow the mid level system to
exit across New England. Unfortunately, it appears the as the
surface low completely falls apart over our area, a weak surface
convergence boundary will be left behind, and looks to set up in the
vicinity if the Genesee Valley/Finger Lakes region. This will mean
as most areas dry out Sunday afternoon, some showers will continue
across this aforementioned area into the afternoon, finally tapering
by off late in the day. Otherwise for the remainder of western and
north-central NY, a low amplitude shortwave ridge will build across
Lower Michigan to southern Ontario in its wake. Drying in the mid
levels will accompany the associated subsidence so that the
precipitation will completely end from west to east with enough
clearing to allow for some afternoon sunshine and a decent ending to
the weekend. Daytime highs will range from the mid 50s to low 60s.

A warm front will work its way northeastward across our forecast
area Sunday night. While this should only result in an increase in
cloud cover, there will be the chance for some showers over the
Niagara Frontier and possibly the Thousand Islands region by
daybreak. Lows will again range from the low 40s across the higher
terrain to the mid and upper 40s elsewhere.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
Very active weather during this time frame with periods of showers
and also chances of thunderstorms.

The mid-level low spinning near James Bay will direct a cold front
towards the eastern Great Lakes Monday morning with increasing
chances for showers. There will also be some thunderstorms with this
boundary, especially as diurnal instability increases in the
afternoon. That said...another mid-level low over eastern Kansas
will begin to advance east towards the Mississippi river valley
by late Monday afternoon. As it does so...it is advertised to
interact with the front over our region. There is some indication
that it will nudge the front back north as a warm front. This would
place us again back in the warm sector with a brief period of
decreasing showers and storms by Monday night. However...it does not
appear to last very long as the eastward advancing low draws the
front back south by Tuesday with accompanying deeper moisture. We
should see our fair share of showers Tuesday but there is some level
of uncertainty as the southern stream low begins to tracks into the
mid-Atlantic region.

Tuesday night...the speed and track of the low will determine
weather we continue to see wet weather areawide or a slow but
gradual drying trend.

Overall...near to a tad bit above normal max temps with highs in the
upper 60s to low 70s. Lows will generally be found in the 50s.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
A weakening mid-level low centered over the northern Quebec
Wednesday morning will continue to pull northeast into the Canadian
Maritimes by Thursday morning. Meanwhile, ridging to the west across
the Upper Midwest and western Great Lakes Wednesday will build
across the remainder of the Great Lakes into Thursday night before
the next trough dives southeast across the Central Plains Thursday
night into the start of the weekend.

With weakened low and associated mid-level trough overhead overhead
of the area Wednesday, rain showers associated with the cold front
the crossed the area Tuesday, will gradually end from northwest to
southeast Wednesday.

As the aforementioned mid-level ridging pushes east across the Great
Lakes, associated surface high pressure will also move into the
eastern Great Lakes. This will result in a period of dry weather
Wednesday night thorugh much of Thursday.

The next chance for showers will return Friday and last into the
start of the weekend as warm front pushes across the area. Model
guidance this far out remains differed with the placement and track
of the upper level features and low level features. Therefore, kept
rain shower chances on the lower end due to the lack in confidence.

Expect a gradual warming trend throughout much of next week, with
subtle warming each day. By the end of the week the temperatures
will have rebounded to slightly above normal.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
A stacked area of low pressure will approach from southwestern
Ontario Province. This will continue the slow degradation of flight
conditions from west to east through this evening. Most low decks
are currently SCT/BKN in the low VFR range (3-5kft). Exception is
across the western Southern Tier (KJHW) where MVFR CIGS continue to
be observed.

A swath of showers and possible thunderstorms ahead of this system
will continue to work across the eastern half of our area through
the early overnight hours. The precipitation will be accompanied by
CIGS that will lower to MVFR levels across the remainder of the
area, mainly from later this evening into the overnight when IFR
CIGS will become common for most areas south of KBUF and KROC. A
period of IFR CIGS will also become possible across far western NY
(KBUF/KIAG) later tonight into the first part of Sunday morning.
Expect at least scattered showers with some patchy fog across the
region in the wake of the steadier precipitation as the mid level
low moves across the area overnight.

IFR/MVFR CIGS over the region Sunday morning will then gradually
improve to VFR levels from west to east through the afternoon hours
as drier air associated with weak high pressure moves in across the
area. Lingering light showers will continue through midday or so.

Outlook...

Monday and Tuesday...VFR/MVFR with the likelihood for showers and
thunderstorms.
Wednesday...Improving conditions with precipitation exiting.
Thursday...VFR weather.

&&

.MARINE...
Mainly light, variable winds (less than 10 knots) will be the rule
through the most of the weekend, before a more pronounced
southwesterly flow (10-15 knots) develops ahead of a warm front
approaching from the west toward the tail end of the weekend.

&&

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

&&

$$

SYNOPSIS...JM/RSH
NEAR TERM...JM/RSH
SHORT TERM...AR
LONG TERM...EAJ
AVIATION...JM/RSH
MARINE...JM/TMA