753
FXUS61 KBUF 011019
AFDBUF

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

.SYNOPSIS...
Expansive high pressure will build across the Great Lakes today,
then to New England on Tuesday. This will help to clear out any
lingering cloud cover this morning...while otherwise 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/...
Sprawling surface high pressure will build eastward across our
region through today and tonight...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 this morning giving way to plentiful sunshine by this
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 this afternoon...today`s highs 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
tonight...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 today and tonight will only inch their way up into the mid to
upper 50s in most places during Tuesday...thereby guaranteeing
continued comfortable humidity levels. Enjoy!

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
An anomalously strong (+2std / 20-30yr RI) 596dm sub tropical 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. While
the confidence is high for this solution...the same cannot be said
for the timing of features that will drive convection.

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 that will support an increasing
coverage of showers and thunderstorms. The airmass by this time will
be 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 one to two inches.
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 abv H7 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 cross our region Thursday night. While most guidance packages
favor a dry passage...our airmass will be warm and moderately
humid...so will maintain slight to low chc pops over the western
counties for a passing shower or thunderstorm. Can easily see the
night being more active than consensus.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
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 /10Z MONDAY THROUGH FRIDAY/...
Lingering MVFR to lower-end VFR-level clouds (with the lowest
ceilings across the higher terrain) will continue to give way to
clearing skies from northwest to southeast this morning.
Thereafter...unlimited VFR conditions will prevail through the rest
of today and tonight as high pressure builds eastward across the
Great Lakes.

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... Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
While conditions on Lake Ontario have fallen to a little below
advisory criteria...gradually diminishing northerlies and residual
wave action will continue to promote rather choppy conditions on
both lakes through this morning...before conditions improve more
markedly during this afternoon.

Much more favorable boating conditions will return late this
afternoon 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 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...JJR
NEAR TERM...JJR
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...JJR
MARINE...Hitchcock/JJR