598
FXUS61 KBUF 011757
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
157 PM EDT Mon Jul 1 2024

.SYNOPSIS...
High pressure will deliver fair dry weather through Tuesday. 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/...
Fair dry weather today as expansive high pressure to our west builds
into the Lower lakes.

With 850 mb temps running between +8C and +10C range highs will be
found from the upper 60s across the higher terrain to the lower 70s
across the lower elevations.

Tonight...clear skies will promote good radiational cooling with
mercury readings to fall back into the mid-upper 40s across interior
portions of the Southern Tier/North Country to the lower to mid 50s
elsewhere.

Tuesday...a return flow on the backside of the departing ridge will
allow highs to climb back to the mid 70s to lower 80s. That
said...it will still be comfortable will low humidity levels.
Enjoy!

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
An anomalously strong (+2std / 20-30yr RI) 596dm subtropical ridge
centered over the Deep South during this period will be the dominant
weather player for our forecast area...as it will essentially serve
as a heat pump for temperatures that will average well above normal
while guaranteeing moderately high humidity.

The easy part of this part of the forecast period will come Tuesday
night when the crest of the mid level ridge will slowly exit to our
east...while the associated area of sfc high pressure will be
anchored in the vcnty of Long Island. This will assure us of fair
dry weather...but mid and high level moisture spilling over the
aforementioned ridge will at least partially shroud our moonless
skies. It will be noticeably warmer than the previous two nights...
as mins will range from the mid and upper 60s across the lake plains
to the lower 60s across the higher terrain.

While the bulk of Wednesday will be rainfree, a shortwave crossing
Lower Michigan in the morning will push a pre-frontal trough across
our region during the afternoon. This will support an increasing
coverage of showers and thunderstorms from west to east, with wet
weather likely across far western NY by early Wednesday evening. The
airmass will become moderately humid with Td`s returning to the mid
and upper 60s, but more importantly the door will have been opened
for the return of GOMEX moisture with PWAT values surging back to
around 2 inches. This should allow any convection to include some
torrential downpours with LOCALIZED rainfall amounts of 1-2 inches.
With modest instability (500-1000J/kg MLCAPE) and bulk shear
magnitudes (30-35kts) out ahead of the pre-frontal wave, not out of
the question that some storms may be capable of strong wind gusts as
well. This potential is reflected in SPC`s latest Day 3 Convective
Outlook, which highlights far western NY in a Marginal Risk.
Otherwise...it will be quite warm with max temperatures ranging from
near 90 across the lake plains to the mid 80s most elsewhere.

The pre frontal sfc trough will complete its passage across our
forecast area Wednesday evening...while the plume of deep sub
tropical moisture will push off across New England. The widespread
shower and thunderstorm activity associated with this feature will
taper off from west to east in the process. A weak cold front will
immediately follow...but with much of the moisture above H700
stripped away, this passage will go relatively unnoticed. In fact,
there will be little if any change in the airmass especially near
the sfc where Tds will remain elevated within a few degrees of 70.

The weak cold front will settle to our south by Thursday morning...
lining up west to east from about the Mason Dixon line to the Upper
Ohio valley where it will be stalled through Thursday night. One
would think that being on the northern side of this boundary that it
would be cooler and less humid...but as mentioned there will not be
a true airmass change. It will remain very warm and humid for the
Fourth of July holiday with mercury levels only a few degrees lower
than the day before. From this vantage point...the day should be
largely rainfree...but an afternoon shower cannot be ruled out
across the Srn Tier.

The remnants of a convectively enhanced shortwave are then forecast
to move south of our region across PA Thursday night. While most
guidance packages favor dry weather across the forecast area, our
airmass will be warm and moderately humid so will hold onto slight
to low chc PoPs over the southern counties for a passing shower or
thunderstorm. Will need to keep an eye on this shortwave as a
further north track can`t yet be ruled out and could spell a much
more active night than forecast across WNY, especially for the
Southern Tier counties.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
A low amplitude longwave trough will be centered over the middle of
the country during this period...and as such there is high
confidence that our temperatures will remain above typical early
July levels.

In regards to precipitation...Friday/Friday night should be the
most active part of this period. Remember the stalled frontal
boundary to our south (from late Thursday/Thurs night)? Well...a
vigorous shortwave and corresponding broad sfc reflection moving
across the Upper Great lakes will push the once stalled frontal
boundary back towards our forecast area. Guidance is not in
agreement as to whether the boundary makes it back through our
region...but it should be close enough to support at least scattered
shower and thunderstorm activity...especially over the Southern
Tier. Can easily see subsequent forecasts raising pops to likely for
that particular area.

The boundary will finish its passage through our region Friday
night. This will be marked by more showers and thunderstorms...and
with PWAT values once again swelling to around 2 inches...any
convection will have the potential to produce locally heavy rain.
This should prove to be the muggiest night of this long term period.

As the strong shortwave over the Upper Great Lakes ejects into
eastern Canada on Saturday...the aforementioned sfc low will push a
cold front though our region. While consensus is that this will
occur early Saturday morning...a delayed passage would result in a
more pessimistic forecast. At this point though...the front should
move through early enough so that an ensuing dry slot will push
across our region during the day so that there will only be the
chance for an afternoon shower. Once again...little change in
temperature and humidity is expected in the wake of the cold front.

High pressure over the spine of the Appalachians Saturday night and
Sunday will then provide generally rainfree weather over our
forecast area to end the weekend.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Some fair weather cu will be found across the area...otherwise VFR
will be found at all terminals.

Outlook...

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

&&

.MARINE...
Northerly flow will produce choppy conditions on both lakes with
waves of 1 to 3 feet this afternoon.

As the expansive high pressure to our west builds east winds and
waves will begin to relax by this evening. Much more favorable
boating conditions will then take hold through Tuesday as this high
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 Wednesday afternoon
and night...with locally higher winds and waves possible in and
near any thunderstorms.

&&

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

&&

$$

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