-- Discussion containing changed information from previous version are highlighted. --
591
FXUS61 KBUF 242025
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
425 PM EDT Mon Jun 24 2024

.SYNOPSIS...
Scattered showers east of Lake Ontario will end early this evening,
otherwise clearing skies and cooler conditions are expected tonight.
Warm and humid conditions will return Tuesday and especially
Wednesday when a pair of frontal passages will support showers
and potentially strong thunderstorms.

&&

.NEAR TERM /THROUGH TUESDAY/...
The center of a 998 mb low located along the Maine coast continuing
to support wrap around moisture, with a scattered coverage of
showers east of Lake Ontario this afternoon. This activity has
been trending downward and expect this activity to wind down
between 22Z and 00Z. Cloud cover and lacking instability should
limit any thunderstorm development across the North Country
this afternoon.

Surface high pressure will begin to build east into the lower Great
Lakes tonight. Clearing skies and light winds will support good
radiational cooling and support overnight low temperatures in the
50s, along with the potential for some Southern Tier valley fog
and perhaps some fog east of Lake Ontario where rain lingered
today.

Surface high pressure will slide across and then east of the region
Tuesday, with a southerly return flow developing. Some minor height
rises aloft within general flat ridging will bring about a warm
advective flow, sending temperatures back into the lower to mid
80s, although humidity levels should remain on the comfortable
side with dewpoints staying below 60F for the most part.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
A progressive quasi-zonal flow will continue right through next
weekend and into early next week, as the strong upper level ridge
that brought the oppressive heat and humidity to the region last
week remains suppressed over the southern half of the CONUS. This
regime will provide bouts of comfortable temperatures along with
periods of more typical mid summer warmth ahead of a couple cold
frontal passages...one mid week and the second this weekend. This
will also translate to periods of dry time, with storm chances
ramping up along and ahead of the aforementioned frontal boundaries.

Heading into Tuesday night, a mid level ripple will move across
southern Quebec first half of the night with the southern flank of
this feature just grazing the area, while an associated warm frontal
segment in the low levels slides northeast across the area at the
same time. PWATs will ramp up into the 1.25-1.5" range. Better
forcing will be toward the Saint Lawrence Valley where the better
mid and upper level dynamics will reside, thus will have high Chc to
low Lkly PoPs toward the North Country, trailing off to low Chc
toward southwestern NYS. Some embedded thunder possible as well.
This will be quickly followed up by an initial cold front
approaching from the northwest that will move into the area later
Tuesday night into Wednesday morning. The timing of the front is a
bit sooner than previously advertised, however a wave riding
northeast along the boundary may significantly slow its
southeastward progression, possibly lingering the front across areas
south of the NYS Thruway into Wednesday afternoon. Here in lies the
problem as this will allow our severe weather chances to remain in
place across these areas, while areas to the north would have much
lower chances for strong storms. Currently, SPC has the northern
edge of a Day 3 Marginal Risk just clipping the western Southern
Tier, which lines up well with our thinking of the frontal
positioning. PWATs near 1.5" may also lead to some areas of heavy
rainfall with the strongest storms, again mainly south of the NYS
Thruway if this scenario holds true. It will be a warm day with more
humid conditions. Highs will mainly be in the upper 70s to low 80s.

As the wave pushes east of the area, the initial cold front will
push south of our area. A secondary cold front will then cross the
region Wednesday night into Thursday morning with a much more
refreshing airmass moving into the region in its wake. With deeper
moisture departing east with initial wave, not expecting more than
some scattered showers/isolated rumble of thunder as the boundary
passes through the area. Depending of the speed of the front, a few
showers may linger across eastern areas Thursday morning, otherwise
a dome of high pressure builds in from the west bringing dry weather
through Friday with comfortable temperatures and humidity levels. In
fact, below normal temperatures are expected Thursday with highs
ranging from the upper 60s to mid 70s. Similar to the first part of
the work week, high pressure then slides east of the area Friday
with a warming southerly return flow boosting temperatures back near
normal with highs mainly in the mid 70s to low 80s.

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...

As mentioned above, quasi-zonal flow remains in place through this
period, with two notable features being a warm front followed by a
cold front, both slated to push across the area this weekend. Both
of these features will bring the next round of showers and storms to
the region, however differences in exact timing of said frontal
boundaries continues to be a point of discrepancy amongst the "big
3." Nothing too uncommon at this time range. With this in mind, will
keep the goal posts a bit wider, with most of the more active
weather likely occurring somewhere in the Friday night through
Saturday night timeframe. Will be able to shrink this window down as
we get closer in time. That said, there will once again be a
secondary cold front crossing the region which brings the return of
dry weather and yet another cooler, more refreshing airmass to
western and northcentral NY in its wake. Question is timing of this
secondary boundary as well. If the later in time solution comes to
fruition, a few showers/isolated storms could linger into at least
the first part of Sunday.

Warm and humid to start the weekend will trend to cooler and less
humid conditions for the second half of the weekend into the start
of the new work week.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
The passage of the cold front by Wednesday night will again bring in
another much more refreshing airmass into western and north central
New York for the latter part of the work week. This should
result in dry weather Thursday and Friday with highs lower to
mid 70s Thursday, then as the airmass starts to modify with
surface high moving east of our area Friday will see high
temperatures in the upper 70s to mid 80s. Dew points in the 50s
will mean very tolerable humidity levels for late June.

Mid summer warmth and humidity along with shower/storm chances will
return as we head into the weekend as the next frontal system
approaches from the west. Depending upon the timing of the frontal
passage Saturday should be the more uncomfortable of the two weekend
days with highs well into the 80s and higher humidity.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
Moisture wrapping around an eastern Maine low keeping some
scattered showers in across the eastern Lake Ontario region this
afternoon, but restrictions at KART look to have ended with
CIGS improving to VFR. Elsewhere SKC-SCT040 for all other
terminals this afternoon. Northwest winds at 10 to 15 knots will
diminish by late afternoon.

High pressure building in tonight with mainly SKC across the region.
Some patchy fog is possible in the Southern Tier valleys and east of
Lake Ontario. Restrictions are possible at both KJHW and KART after
06z.

Outlook...

Tuesday...VFR.
Tuesday night and Wednesday...MVFR/VFR with a chance for showers and
thunderstorms.
Thursday and Friday...Mainly VFR.
Saturday...Restrictions possible with a chance of showers and
thunderstorms.

&&

.MARINE...
Small craft advisories include all of the Lake Ontario nearshore
waters due to northwesterly flow through much of today. Winds and
waves will begin to subside this evening as high pressure moves into
the Ohio Valley today through Tuesday.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement until 6 PM EDT this evening for
     NYZ001>003-007.
     Beach Hazards Statement until 11 PM EDT this evening for
     NYZ004>006.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LOZ042.
         Small Craft Advisory until 8 PM EDT this evening for
         LOZ043>045.

&&

$$

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