866
FXUS61 KBUF 251027
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
627 AM EDT Sat May 25 2024

.SYNOPSIS...
While today will NOT be a complete wash out...showers and gusty
thunderstorms will develop during the midday and afternoon in
response to a pair of fronts moving through the area. Weak high
pressure will then allow fair weather to return later tonight
with the finest weather of the weekend slated for Sunday.
Looking at the end of the long Memorial Day weekend...a complex
storm system over the Upper Great Lakes will support very
unsettled weather for Monday...including the potential for
drenching thunderstorms.

&&

.NEAR TERM /THROUGH SUNDAY/...
Gorgeous weather this morning will deteriorate during the course of
the day with showers and thunderstorms becoming likely for some
areas during the afternoon. Those with outdoor activities planned
should keep an eye to the sky and pay attention to updated forecasts
and possible statements/warnings regarding the risk for strong
thunderstorm activity. The details...

Stacked low pressure over the prairies of Manitoba will push a far
reaching occlusion across the Upper Great Lakes today with a poorly
organized sfc low along the boundary extending a warm front through
our region. While beautiful weather will persist over the forecast
area this morning...a modest 30kt low level jet impinging upon the
advancing warm front will lead to some showers and isolated
thunderstorms over the western counties by midday. This activity
could initially be focused along a low level convergence zone
that will extend from Niagara county eastward to Wayne county.

Scattered showers and isolated thunderstorms will then spread across
the Eastern Lake Ontario counties...as the warm front will advance
to the northeast this afternoon. In the warm sector behind the warm
front...notably more humid air will serve as a breeding ground for
more widespread and robust convection over the western counties
during the mid and late afternoon. PWAT values will approach 1.5"
with Td`s climbing to arnd 60 F. This moisture rich environment will
encourage convection to include torrential downpours...and with bulk
shear values forecast to be in the vcnty of 25-30 kts...there could
be some storms that could contain hail and/or strong wind gusts. The
greatest threat for strong thunderstorms over the western counties
will take place between 2 and 6 PM ahead of a cold front. These
storms will then make their way across the Eastern Lake Ontario
counties between 5 and 8 PM.

By sunset...the strongest convection should be east of our area with
partial already taking place over the far western counties. The
residual showers will continue to end from west to east throughout
the evening. This clearing...coming on the heels of fairly
widespread convection...could lead to some late night fog and
stratus as we push into the wee hours of Sunday morning.

The nicest day of the three day weekend can then be expected on
Sunday...as a burgeoning shortwave ridge and corresponding weak sfc
high will move across the forecast area. While there may be some low
clouds around to start Sunday morning...all areas can fully
anticipate sun filled skies for the midday and afternoon. It should
be a fine day for outdoor activities with sunshine boosting
afternoon temperatures into the mid 70s to near 80.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
A shortwave trough over the Pacific Northwest this morning will
track southeast into the central Plains by Sunday morning. As the
trough tracks southeast, a sfc low will develop lee of the central
Rockies and center of the mid-Mississippi Valley by Sunday evening.
Out ahead of the sfc low and shortwave trough a warm front will push
north crossing the NY/PA line during the late evening and overnight
on Sunday night. As the front pushes north, showers along the front
will move into the forecast area (around Midnight), becoming better
organized as a shortwave trough tracks along the front. There is
still uncertainty among guidance for Sunday night as too how
organized the showers become, in part due to timing differences of
the warm front and the shortwave trough.

By Monday morning, the sfc low will be centered over lower Michigan,
and continue to track northeast, centering near the Georgian Bay by
Monday evening. The system will also start to occlude in the
process, becoming more vertically stacked with its mid-level low.
This will keep the region within the warm sector of the system for
Monday. Thunderstorms are also expected starting early Monday
morning, continuing through most of the day. This will be the result
of large scale forcing, increasing instability values of over 1,000
J/kg and bulk shear values of around or a little over 30 knots. An
influx of GOMEX moisture, combined with the large scale forcing and
forcing from a LLJ over the region will result showers that will
have some heavier rainfall rates. Increased potential for heavier
showers within thunderstorms expected as well. With the above
mentioned instability and shear values, the potential exists for at
least strong thunderstorms with gusty winds, with the Storm
Prediction Center placing much of the forecast area in a `Marginal
Risk` for Monday. The best potential for thunderstorms will be south
of Lake Ontario.

Monday night, steadier showers will track northeast and coverage of
the showers will become less through the night from west to east as
an occluded front pushes northeast and east into Canada & New
England. Some lingering/embedded thunderstorms will still be
possible through the first half of the night.

Widespread rainfall amounts for Sunday night through Monday night of
half to one inch is possible for most of the forecast area, with the
highest amounts expected for areas east of Lake Ontario. Localized
higher amounts are also possible due to thunderstorms as well.

Temperatures for Sunday and Monday night will be in the upper 50s to
mid 60s, with Monday night being the slightly cooler night behind
the passing front. Monday afternoon temperatures will be in the
upper 60s to near 80 from the higher terrain to the lower
elevations.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The departing vertically stacked system from earlier in the week
will continue to cause showers into the middle of the week as it
will take a few incoming troughs to finally push it out of the
region. There will also be a few passing cold fronts that pin wheel
around the system within the cyclonic flow. Showers should start to
taper off by the afternoon on Wednesday.

Mostly dry conditions expected from Wednesday night through the rest
of the week as a large area of high pressure and large ridge move
into the eastern half of the CONUS.

Temperatures will be below normal for most of the period, with
afternoon highs returning to near normal by Friday. Wednesday and
Thursday will be the coolest days with high temperatures around 5 to
10 degrees below normal.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
While VFR conditions can be expected for the vast majority of
today...the passage of a pair of frontal boundaries will support
some gusty thunderstorms during the midday and afternoon. The
greatest risk for the convection over the western counties will
come between 18 and 22z...and for sites east of Lake Ontario
between 20 and 00z.

Convection from the afternoon will move out of the area during the
evening hours. While this will leave primarily VFR conditions in
place through 06z...clearing skies will lead to some areas of fog
and stratus that will result in fairly widespread MVFR to IFR
weather through daybreak Sunday.

Outlook...

Sunday...Improving to VFR.
Monday...Restrictions likely with showers and thunderstorms.
Tuesday and Wednesday...Restrictions possible with showers.

&&

.MARINE...
Winds across the Lower Great Lakes will become more variable
today...as a warm front will push through the region. This could
allow for some lake breeze circulations to develop. A few gusty
thunderstorms will be possible during the afternoon ahead of an
approaching cold front with the potential for locally higher winds
and waves.

With the cold frontal passage winds turn east-northeasterly
generally under 10 knots Sunday...as high pressure will briefly
build across the lower Great Lakes.

More notable winds will occur on Monday into Tuesday with increasing
southerly winds early Monday taking on a more west-southwesterly
component Monday afternoon into Tuesday. Winds could nudge into the
15 to 25 knots range with possible small craft headlines needed
during this time period. Scattered gusty thunderstorms will also be
possible Monday.

Boaters should continue to monitor the forecast, especially given
the holiday weekend which will likely increase boating activity.
This will especially be the case on Monday as conditions on the
lower Great Lakes will likely deteriorate.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...SW
LONG TERM...SW
AVIATION...RSH
MARINE...TMA