579
FXUS61 KBUF 010631
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
231 AM EDT Mon Jul 1 2024

.SYNOPSIS...
Lingering clouds and scattered light showers will give way to
clearing skies late tonight and early Monday morning as high
pressure and drier air build into the region. The high will then
build across the Great Lakes Monday and to New England on
Tuesday...while providing us with a spectacular start to the week.
Heat and humidity will then make a return on Wednesday out ahead of
an approaching cold front...which will bring our next round of
showers and thunderstorms as it crosses our area late Wednesday
afternoon and Wednesday evening.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 0630z...the main upper level trough axis was draped squarely
across our region. Attendant cool cyclonic upslope flow and lake
processes were still generating a wealth of cloud cover and some
embedded scattered light showers/sprinkles... however recent
satellite imagery shows that all this is now starting to erode
across far WNY. This drying/clearing trend will gradually spread
southeastward through the rest of the night as the upper trough axis
slips off to our southeast and surface high pressure/drier air over
the Upper Great Lakes begins making further inroads into our region.
Lows will mostly be in the lower to mid 50s...with a few upper 40s
sprinkled across the Tug Hill and interior portions of the Southern
Tier.

The expansive surface high will then continue to build eastward
across our region through Monday and Monday night...before slowly
drifting out across New England on Tuesday. This will provide us
with a spectacular start to July...with any lingering upslope and
lake effect clouds early Monday morning giving way to plentiful
sunshine by Monday afternoon...and largely clear skies then
persisting until later Tuesday...when some cirrus-level cloudiness
will begin spilling across our region in concert with developing
warm air advection aloft.

The fair weather will also be accompanied by rather comfortable
temperatures and humidity levels. With 850 mb temps running between
+8C and +10C during the afternoon...highs on Monday should range
from the upper 60s across the higher terrain to the lower 70s across
the lower elevations. Ideal conditions for radiational cooling will
then allow lows to range from the mid-upper 40s across interior
portions of the Southern Tier/North Country to the lower to mid 50s
elsewhere Monday night...before the warmer return flow on the
backside of the departing ridge allows highs to climb back to the
mid 70s to lower 80s on Tuesday. Meanwhile surface dewpoints in the
mid 40s to lower 50s Monday and Monday night will only inch their
way up into the mid to upper 50s in most places Tuesday...thereby
guaranteeing continued comfortable humidity levels. Enjoy!

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A large expanse of surface high pressure underneath a stout mid-
level ridge will lie across central NY to open the period Tuesday.
Dry weather will persist through Tuesday night as the ridge slowly
shifts towards and away from the New England coast. The onset of
warm advection on the backside of the surface high will allow high
temperatures Tuesday in the upper 70s to low 80s. Dewpoints will
also rise a few degrees though should remain in comfortable
territory, generally averaging in the 50s. Deepening southerly flow
Tuesday night will lead to rather warm overnight low temperatures,
especially across the Lake Plains where temps will only dip into the
upper 60s.

Unsettled weather returns later Wednesday and into Wednesday night
as a robust mid-level trough and attendant surface low track from
northern Ontario to Quebec across Hudson Bay. This will initially
cause warm front to lift out of the Ohio Valley and into the
forecast area Wednesday morning, before the system`s cold front sags
southeast through the region Wednesday night. While the initial
frontal passage in the morning is expected to be dry, moisture
advection into the warm sector behind it will allow for increasing
chances for showers and thunderstorms later in the afternoon and
into the evening, particularly from the Genesee Valley westward. Mid-
range guidance indicates PWATs approaching 2" ahead of the cold
front Wednesday afternoon which could support some locally heavy
downpours, especially in the western Southern Tier where instability
is expected to be greater. Otherwise, it will be a rather sultry day
as the increasing moisture will also lead to muggier dewpoints
values in the mid to upper 60s, while high temps climb WELL into the
80s in most areas. The typical warm spots across the interior
valleys such as Dansville may even breach the 90 degree mark
Wednesday afternoon.

The cold front will make its way through the eastern Great Lakes
Wednesday night before it runs up against the strong offshore ridge,
causing it to stall out across Pennsylvania. Broad scale ascent
along a ribbon of deeper moisture will allow for a round of
widespread showers and a few storms just out ahead of the cold front
Wednesday night, mainly in the first half of the night. Weak surface
high pressure and subsidence drying should allow much of western NY
to begin drying out in the second half of the night, though lower-
end chances for showers will otherwise linger through the pre-dawn
hours as the front`s momentum slows over the region. Temperatures
Wednesday night will likely depend on the exact timing of the front,
though it is expected to be rather muggy with mid 60s to low 70s for
overnight lows.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A secondary shortwave trough will round the base of the longwave
trough Thursday, pulling longwave pattern east across the lower
Great Lakes and New England Thursday night.The exiting shortwave
will support the cold front to finish sliding southeast across the
area Thursday, ushering in a cooler and less humid airmass into the
region. Thursday will take on a drying trend with just a few
scattered showers and thunderstorms heading into the afternoon.
Temperatures for the holiday will feature highs in the low to mid
80s.

As the longwave trough pull east across the lower Great Lakes and
New England Thursday night placing zonal flow across the area, the
now stalled cold front to the south of the area. While the area will
remain mostly dry, a few showers and thunderstorms can`t be ruled
out, especially along and near the New York/Pennsylvania state line.

Zonal flow Friday will give way to the next trough diving across the
Great Lakes through the weekend, it is this point the the forecast
the model guidance begins to diverge with the timing and positioning
of the next shortwave and corresponding cold front for Friday night
through Sunday. With this in mind, have chances for showers and
thunderstorms lasting throughout the weekend with the better chances
for the weekend being Saturday, but time will tell being this far
out.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
Lingering MVFR to lower-end VFR-level clouds (with the lowest
ceilings across the higher terrain) and scattered light showers will
gradually give way to clearing skies from northwest to southeast
late tonight and Monday morning. Thereafter...unlimited VFR
conditions will prevail through the rest of Monday and Monday
night as high pressure builds eastward across the Great Lakes.

Outlook...

Tuesday...VFR. Wednesday...VFR, then MVFR with showers and
thunderstorms late in the day and Wednesday night.
Thursday...Mainly VFR with a low chance of a shower or thunderstorm
across the western Southern Tier.
Friday... Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
Moderate northwesterlies and northerlies will gradually diminish
late tonight and early Monday morning...allowing advisory-level
conditions along the south shore of Lake Ontario to gradually
subside. This being said...the northerly flow and residual wave
action will continue to promote choppy conditions on both lakes
through Monday morning...before conditions improve more markedly
during the afternoon.

Much more favorable boating conditions will return late Monday
through Tuesday as high pressure drifts across the Lower Great Lakes
and into New England.

Freshening southerly winds will then follow for later Tuesday night
and Wednesday out ahead of an approaching cold front...however the
offshore nature of the flow will help to direct the greatest wave
action across Canadian waters...with conditions largely remaining
below advisory criteria as a result. Of more concern to boaters will
be an increasing potential for showers and thunderstorms as the cold
front approaches and crosses the region later Tuesday afternoon and
night...with locally higher winds and waves possible in and near any
thunderstorms.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement until 5 AM EDT early this morning for
     NYZ002>006.
MARINE...Small Craft Advisory until 5 AM EDT early this morning for
         LOZ042>044.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...PP
LONG TERM...EAJ
AVIATION...JJR
MARINE...Hitchcock/JJR