854
FXUS61 KBUF 300206
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1006 PM EDT Sat Jun 29 2024

.SYNOPSIS...
A cold front will move across the region overnight, producing a
few showers and thunderstorms with its passage. The front will
bring less humid conditions and drier weather for Sunday. High
pressure will build in on Monday which will bring fair and dry
weather which will last through Tuesday.

&&

.NEAR TERM /UNTIL 6 PM SUNDAY EVENING/...
Late this evening, radar shows most of Western NY is rain-
free, with scattered showers and storms east of Lake Ontario.
There remains some instability in place tonight with LAPS
showing CAPE 500 to 1000 J/Kg. Wind shear has diminished from
earlier, but the 00Z Buffalo sounding still has winds of 40
knots at 850mb. There remains a marginal risk for severe weather
overnight, mainly just ahead of the cold frontal passage. Storms
may also produce brief heavy downpours with precipitable water
values still near 2 inches ahead of the front. Patchy fog is
also possible.

With the passage of the initial cold front it will become quite
breezy Sunday, with increasingly more comfortable conditions
due to the tumbling Td`s. Interestingly enough...our high
temperatures are advertised to peak in the low to mid 70s by
midday/early afternoon then slowly falling thereafter. This is
unusual for this time of year... so this gives you a semblance
of how strong the cold advection will be in the wake of the
first cold front. MaxTs Sunday will generally be found in the
70s.

&&

.SHORT TERM /6 PM SUNDAY EVENING THROUGH TUESDAY NIGHT/...
Dreary weather Sunday night as an upper level trough axis and
secondary cold front pivot southeast through the eastern Great
Lakes. With recently sampled lake temps near +21C, 850H temps
bottoming out near +5C and northwesterly upslope flow coupled with
weak difluence aloft will maintain a wealth of cloud cover and some
scattered showers overnight. Will continue to hedge above blended
guidance for sky/PoPs as it continues to be too aggressive with the
overnight clearing and drying given the expected pattern. Greatest
chances for any measurable precip will be earlier in the night east
of Lake Ontario and across the higher terrain of the Finger Lakes
region, while far western NY should begin clearing out very late in
the night. Otherwise, insulation from the extra cloud cover should
somewhat balance out with the chilly airmass and yield comfortable
sleeping temperatures in the 50s, with upper 40s possible across the
hilltops.

Excellent weather will then be in place as we move into the first
day of July as a broad area of surface high pressure initially
centered over the western Great Lakes Monday morning migrates east,
being directly overhead by Monday night before shifting off the New
Jersey coast by Tuesday evening. Temps aloft will already begin
warming Monday, though given the cool start surface temps will
likely only reach the upper 60s and low 70s under mostly sunny
skies. Monday night will again be on the cool side owed to the
clearer skies, with lows ranging from the upper 40s across the
interior hilltops to mid 50s near the lakeshores. Mid/high clouds
will increase through the day Tuesday out ahead of a warm front
lifting through the Ohio Valley. Temps at the sfc and aloft will
continue to warm on the western periphery of the surface high
Tuesday and Tuesday night, with temps topping out in the upper 70s
to low 80s and lows ranging in the 60s respectively.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
Warmer, unsettled weather returns to the forecast as we move later
into the week. This comes as weak mid-level ridging shifts east of
the Great lakes Wednesday as is replaced with nearly zonal flow
aloft extending back toward the lower Midwest. Meanwhile, a
weakening mid-level trough will trudge east across James Bay from
northern Ontario to Quebec, causing several shortwave disturbances
to ripple through the overhead zonal flow, bringing on and off
chances for showers and thunderstorms through the end of the week.

The first of these opportunities for wet weather will arrive
Wednesday afternoon. A large surface low attendant to the trough
near James Bay will sag its elongated cold front southeastward
across Ontario Province and towards the eastern Great Lakes. Diurnal
convection will be possible during peak heating hours as the
forecast area sits within the system`s warm sector. A more
widespread round of showers and possibly a few additional
thunderstorms is expected Wednesday night as the front moves through
then stalls just south of the region, before the area dries out late
Wednesday night into Thursday morning.

Forecast uncertainty increases as we move further into Thursday and
towards the weekend. Long range guidance is in general agreement on
the stalled frontal boundary remaining to our south through
Independence Day, with an area of subsidence drying extending across
the forecast area from the upper Great Lakes. This being said, the
GFS is much further north with the placement of the boundary than
the ECMWF/CMCNH, both of which hint at some possible light diurnal
shower activity developing. This is reflected in the forecast as low-
end chances for showers (15-20%) in most areas Thursday afternoon
and evening, with slightly better chances (~30%) across the Southern
Tier in closer proximity to the boundary, where some thunderstorms
may be possible as well. Thereafter, a compact shortwave racing
across the Lower Great Lakes/Ohio Valley Thursday night will take
aim at the forecast area by Friday morning, followed by a larger
surface low which will move across the Great Lakes Saturday. As is
typical at this range, uncertainty is high in strength, timing, and
track of these systems which will also likely be influenced by how
they interact with the stalled boundary south of the area. Therefore
have stuck close to deterministic NBMs Chc PoPs Friday through
Saturday until details come into better focus.

For temperatures this period...Summer`s warmth will return to the
forecast area out ahead of the cold front Wednesday, with highs well
into the 80s likely in most areas. Temperatures cool a few degrees
with a bit less humidity by Thursday. Temperatures Friday will be
similar, likely cooling a bit more to the upper 70s/low 80s by
Saturday.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
A mix of MVFR and VFR cigs late this evening, with lots of
lingering low level moisture. Scattered showers and
thunderstorms ahead of a cold front which will move across the
area late tonight. These will bring localized MVFR or lower
flight conditions.

Increasing moisture with the cold front will also bring lower
cigs in the MVFR/IFR flight category. Some fog is also possible,
especially east of Lake Ontario and in the Southern Tier.

Showers will taper off at most locations during Sunday, and
cigs will gradually lift and break up some. Expect mainly VFR
flight conditions by Sunday afternoon.

Outlook...

Sunday night through Tuesday...VFR.
Wednesday...VFR/MVFR with showers and thunderstorms likely.
Thursday...Mainly VFR with a chance of a shower or thunderstorm
across the S. Tier.

&&

.MARINE...
A cold front will approach the region tonight...expect fresh to
strong westerlies in the wake of a front on Sunday. This will
likely lead to a fresh round of headlines for at least the
eastern half of Lake Ontario...while choppy conditions will be
found elsewhere.

Looking further ahead...high pressure drifting across the region Monday
and Tuesday will offer fine conditions for recreational boating with
generally light winds and negligible waves.

&&

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

&&

$$

SYNOPSIS...AR/Apffel
NEAR TERM...AR/Apffel/RSH
SHORT TERM...PP
LONG TERM...PP
AVIATION...AR/Apffel
MARINE...AR/Apffel/RSH