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684
FXUS61 KBUF 291838
AFDBUF

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

.SYNOPSIS...
Showers and thunderstorm will possible through this evening which
could produce torrential downpours and gusty winds. A cold front
will cross the region tonight, with additional chances for showers
or a thunderstorms. The passage of the front will bring in less
humid conditions and drier weather. High pressure builds in on
Monday with dry weather through Tuesday.

&&

.NEAR TERM /THROUGH SUNDAY/...
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Beneficial rains so far...with many locales reporting over 1.25 to
1.5 inches of rainfall through 06Z. The overall lack of instability
has really kept the SVR potential at bay this afternoon. That
said...it wouldn`t take much for storms to fire up given ample shear
(0-6km 50 knts) across the region. So far the main concern has been
the heavy rain that has fallen in many spots. Given the above
mentioned rainfall totals....it wouldn`t take much for flash
flooding to occur if any additional thunderstorms fire up and train
over any given location.

Otherwise...showers and thunderstorms will briefly dwindle in
coverage from west to east beginning this evening. After that...the
cold front will approach from the WNW late tonight and early Sunday
morning. There is some indications we might see a round of showers
with the front...but not all guidance is bullish on this idea. Right
now...the most widespread showers coverage appears to be east of
Lake Ontario.

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.
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&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
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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.
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&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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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.
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&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
A cold front nearing the region will bring showers and thunderstorms
this afternoon and evening which will likely produce periods of MVFR
to IFR conditions.

The showers and thunderstorms will taper off from west to east by
late this evening and tonight...MVFR to IFR cigs will likely remain
across area terminals.

Outlook...

Sunday...VFR/MVFR with scattered showers.
Monday and 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...
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Modest south to southwest wind flow will produce fairly choppy
conditions on area lakes this afternoon..especially well offshore.
Additionally...widespread showers and some thunderstorms will
continue to be possible through this evening.

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.
-- End Changed Discussion --

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 2 AM EDT Sunday for LOZ045.

&&

$$

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