238
FXUS61 KBUF 091057
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
657 AM EDT Tue Jul 9 2024

.SYNOPSIS...
High pressure will slowly push east across New England today,
resulting in a very warm and humid day with the outside chance of an
afternoon shower or thunderstorm. The remnants of Beryl will arrive
into the region late tonight into Wednesday night bringing periods
of heavy rain and thunderstorms. Most areas can expect one to two
inches of rain, although higher amounts will be possible across the
Eastern Lake Ontario region.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure will continue to slowly exit across New England today.
A southerly return flow on the backside of the high will bring in
warm and increasingly humid air. Most temperatures reaching the mid
80s to near 90, with the warmest heat index values possibly
reaching the mid 90s. For the most part, fair weather is expected
today with a general increase in mid and high level clouds.
Lack of large scale forcing will keep afternoon convection to a
minimum, but still may see some terrain induced storms develop
with possible convection along any subtle lake breeze boundary.

A tropically enhanced warm front extending eastward from the
remnants of Beryl will arrive into our region late tonight.
Precipitable water values will push to near 2" as tropical moisture
associated with Beryl surges into our area from the Ohio Valley.
This deep feed of moisture will ride up across the warm front
and result in increasingly widespread showers after midnight.
The rain could become heavy over the far western counties toward
daybreak Wednesday.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
...Significant Rains AND increased severe weather threat continues
from the Remnants of Beryl on Wednesday...

Model guidance fairly well aligned with respect to the track and
strength of the remnants of Beryl as the system tracks just to the
west and north of our area as it slowly moves northeastward while
gradually weakening Wednesday through Thursday.

The remnants of Beryl will be accompanied by a pronounced swath of
tropical moisture (precipitable water values of 2.0 to 2.5 inches)
Wednesday and Wednesday night, supporting a risk for heavy rainfall.
This rich moisture field will be initially lifted by a diffluent
flow aloft and a northward-advancing warm front during the day
Wednesday, followed by the system`s trailing cold front late
Wednesday into the first half of Wednesday night. This will bring
about a near certainty of periods of rain and some embedded
thunderstorms Wednesday and Wednesday night, with the aforementioned
frontal boundaries potentially also serving as foci for training
storms and corridors of enhanced rainfall/resultant flooding risk.
One difference from the previous model run is a slight northward
shift in the axis of heaviest rain now lying from the southern
shores of Lake Ontario ENE across the eastern Lake Ontario region,
where a widespread 1.5 to 2.5 inches of rainfall looks possible at
this time. This will also result in much of the area south of Lake
Ontario becoming firmly entrenched in the warm sector bringing the
severe weather threat to more of our region. As for the heavy
rainfall threat...after discussion amongst surrounding offices and
WPC, decided not to upgrade to a Moderate Risk for Excessive
Rainfall across the eastern Lake Ontario region with fluctuations in
the axis of heaviest rainfall continuing, and thus will keep Slight
Risk for Excessive Rainfall across the entire region. For these same
reasons, will also continue to hold off on the issuance of any Flood
Watches for the time being.

For the increased severe weather risk, the Marginal Risk was
expanded by SPC across all areas south of Lake Ontario with the
exception of the Niagara Frontier and near the lakeshores, with a
Slight Risk now placed across much of the western Southern Tier
later Wednesday afternoon into Wednesday evening. Diurnal
instability and the presence of fairly strong deep-layer shear (0-6
km bulk shear values of 40-50 knots) and veering wind profiles aloft
could result in an environment possibly supportive of some
multicell/supercell storms in the above areas, with damaging wind
gusts being the primary severe weather threat. With this in mind
will expand the mention of gusty winds to these aforementioned
areas. Unfortunately, there will also be an elevated risk for a
tornado or two as is often the case with the remnants of tropical
systems, greatest risk across the interior western Southern Tier
(5%) and 2% within the Marginal Risk area.

As for high temperatures Wednesday, have increased temps a bit south
of Lake Ontario with the anticipated northward shift in the axis of
heaviest rainfall, but will still remain highly dependent upon the
northward progress of the system`s warm front. To its north, a
general ENE flow and more widespread/persistent precipitation will
likely keep readings confined to the 70s (North Country), while to
its south, temps could easily surge well into the 80s. What is more
certain are the humidity levels, as the burgeoning tropical airmass
will likely send surface dewpoints surging into the oppressive lower
to mid 70s in many areas.

The widespread tropical rains will wind down from west to east
during the course of Wednesday night and early Thursday as the
system`s center and trailing cold front pass through our longitude.
In their wake, there will be a lingering chance of much more
scattered/weaker showers and a few more isolated storms on Thursday,
before high pressure and drier air build in Thursday night and usher
in a return to quieter and drier weather from west to east to close
out this period. Otherwise, we can expect temperatures to average
out near to a bit below normal Thursday, although it will remain
quite muggy (though humidity levels will not be as oppressive as
what we`ll see during Wednesday).

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Much quieter weather is expected during this period with our typical
summertime heat and humidity lasting through the period.

Surface high pressure over our area Friday will be wedged in between
a trough over the central Great Lakes and an area of low pressure
tracking up the Eastern Seaboard on Friday. This should provide
mainly dry weather to close out the work week with highs ranging
from the upper 70s to mid 80s.

The trough over the central Great Lakes will track toward and across
the forecast area through the first half of the weekend, weakening
in the process. This will result in the potential for a few showers
across the area, mainly across eastern portions of the region where
increased Atlantic moisture is expected. For the period through the
first half of the weekend, there is still plenty of model
uncertainty among all the guidance, especially with regards to the
timing of the trough crossing the region. Some guidance brings the
trough through quicker before moisture increases to the east,
resulting in less shower potential. Some other guidance is slower
with the trough allowing the moisture to expand north and west,
resulting in increased shower potential for eastern portions of the
area.

After a dry start, shower potential will again increase later Sunday
into the new work week as a few shortwave troughs track across the
area within a quasi-zonal flow over the region. A cold front
tracking southeast across the Great Lakes and into the forecast area
Monday afternoon into Tuesday morning will increase the potential
for showers and storms during this timeframe. Again though, there is
plenty of uncertainty among guidance for timing and shower coverage.

Daytime temperatures near normal to start the period will slowly
trend upward and will be some 5 to 10 degrees above normal for the
second half of the period.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Mid and high clouds will continue to gradually increase from west to
east today, as mid and upper level moisture advects across the area
in front of the remnants of Beryl. A few scattered diurnally driven
showers and storms will be possible inland from the lakes this
afternoon, but very subtle forcing brings lower confidence regarding
a best window for thunderstorm timing and coverage.

Shower and storm chances will continue to increase late tonight as
the remnants of Beryl cross the Ohio Valley. Heavy rain may be
possible across the far western counties after 06Z, impacting the
KIAG, KBUF and KJHW terminals causing flight conditions to drop to
MVFR/IFR

Outlook...

Wednesday...MVFR/IFR with tropical rains and a chance of
thunderstorms.
Thursday...MVFR/VFR with a chance of showers and a few isolated
thunderstorms...with the showers possibly a bit more numerous east
of Lake Ontario.
Friday...Mainly VFR with a low chance of showers and thunderstorms
inland from the lakes.
Saturday...Mainly VFR with a low chance of showers and thunderstorms
well inland from the lakes.

&&

.MARINE...
Gentle to occasionally moderate breezes and minimal waves today will
remain favorable for recreational boating. Despite conditions
staying below small craft advisory criteria to, there will be an
increasing risk for thunderstorms, especially on Lake Erie.

Wednesday will be quite unsettled, as the remnants of Beryl will
move through with times of heavy rain and possibly some gusty
thunderstorms. The active weather will be accompanied by moderate to
occasionally fresh northeasterlies.

&&

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

&&

$$

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