376
FXUS61 KBUF 101133
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
733 AM EDT Wed Jul 10 2024

.SYNOPSIS...
The remnants of Beryl will impact the region today and tonight.
A soaking one to two inches of rain can be expected in many
areas through tonight, with higher amounts possible east of Lake
Ontario. Along with tropical downpours, there will be the risk
for strong to severe thunderstorms this afternoon and this
evening as a cold front moves through. Additional chances for
showers and a few thunderstorms will continue through Thursday,
before high pressure brings improving conditions by the end of
the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
...Significant Rains AND increased severe weather threat from
the remnants of Beryl today into tonight...

...Flood Watch in effect for the eastern Lake Ontario region
this afternoon and this evening...

Beryl`s remnant low over central Indiana early this morning will
move east-northeastward into the lower Great Lakes today as a
mid level trough moves into the Great Lakes. A warm front
currently extending east from the remnant low into Pennsylvania.
Broad ascent and associated area moderate to heavy rain and
embedded thunder rapidly lifting into the region early this
morning. This area will continue expand across the region this
morning as the low and warm front continue to approach the region.
Surge of tropical moisture with precipitable water values in
excess of two inches pushing northward into the region is
expected to result in a window of where rainfall amounts could
exceed an inch this morning.

By this afternoon, the warm front will have moved into New York
State, likely as far north as the I-90 corridor with the low
crossing the Southern Tier of the state. Along and south of the
warm front, growing instability along with very favorable shear
profiles with forecast soundings showing 0-6 km shear values
near 50 knots will greatly increase the severe weather risk,
with damaging winds the primary threat. In addition, 0-3 km
storm-relative helicity values in excess of 300 m2/s2 in
vicinity of the warm frontal boundary will bring the increased
potential for supercells and tornadoes with the main area of
concern just south of a line from Buffalo to Rochester to
Fulton, highlighting the Finger Lakes region and upper Genesee
Valley. This area has been place in an enhanced risk for severe
thunderstorms in the SPC Day One Outlook. In addition to the
severe weather threat this afternoon, widespread tropical rains
will continue north of the warm front, with additional rainfall
amounts likely in excess of an inch. Embedded thunderstorms will
easily enhance these amounts. Overall rainfall amounts from
Buffalo to Rochester should be from 1.5-2 inches. Six hour flash
flood guidance around 2.25" in this area will limit the risk
for widespread flooding concerns. The heaviest rainfall should
focus across the eastern Lake Ontario region with 2+ inches
likely. With heavier rainfall amounts expected in this region a
Flood Watch has been issued which corresponds to WPC`s Day One
moderate risk for excessive rainfall outlook.

It will remain very unsettled tonight, particularly over the eastern
Lake Ontario region. The center of the remnant low will drift across
the far western counties, while the axis of deepest tropical
moisture and associated will be slowly exiting via the Thousand
Islands and St Lawrence valley. This could produce an additional
inch to an inch and a half rain for the Eastern Lake Ontario region,
bringing 24 hour amounts to three inches or more.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
By Thursday morning Beryl`s elongated remnant surface low will be
centered across Lake Ontario and upper Saint Lawrence Valley. The
low will continue to weaken as it slowly tracks into Southern Quebec
and far northern New England through the course of the day. While
its attendant axis of deep tropical moisture that helped produce the
widespread moderate to heavy rains across our area will be well to
our east by this time, the continued close proximity of the remnant
low will keep clouds and at least some scattered lighter showers
going across the area through the day, with a few rumbles of thunder
still possible east of Lake Ontario. A cooler day on tap with highs
ranging through the 70s, although it will remain on the muggy side
with surface dewpoints remaining in the mid to upper 60s.

Thursday night the remnant low will continue to pull further away to
the northeast. This may allow a few scattered showers to persist
through the first half of Thursday night east of Lake Ontario,
before surface high pressure and drier air will ridge further
northeastward into our region from the Ohio Valley. This will help
to bring an end to any lingering scattered showers across eastern
areas with fair dry weather otherwise prevailing. Lows will dip into
the upper 50s to mid 60s as surface dewpoints drop back a little
more, making for at least somewhat more comfortable conditions
compared to the previous few nights.

Friday and Friday night the aforementioned surface ridge will remain
draped across our region, while a weakening mid level trough stuck
across the central Great Lakes Friday, eventually moves by just to
our north and west Friday night. Expecting a mainly dry day and
night, however cannot rule out a scattered shower or two along any
lake breeze circulations during peak diurnal heating. Otherwise,
temps Friday will rebound some with highs mainly in the low to mid
80s, with upper 70s higher terrain and North Country. Lows Friday
night mainly in the low to mid 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Guidance continues to advertise a dry first half of the weekend with
ridging surface and aloft in control. This area of high pressure
will also keep any precipitation associated with a weak wave riding
northeast along the Atlantic seaboard to our east. Mainly dry
weather expected for the bulk of Sunday as well, however a trough
approaching from the central Great Lakes may produce a few scattered
shower/storms later Sunday as moisture and instability start to
increase in advance of this feature. Best precip chances will be
across western NY. It will be very warm with highs well into the 80s
both days, along with humid conditions persisting.

Our weather will become a bit more unsettled for the first part of
the new work week as a couple mid level waves and a surface cold
front cross the region. This will bring better shower and storm
chances, especially if any of these aforementioned features can be
timed with peak diurnal heating. Otherwise, expect very warm and
humid conditions to persist through the end of the period.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
The remnants of Beryl will impact the region through tonight. This
will bring periods of moderate to heavy rain along with a few
embedded thunderstorms this morning. This will result in flight
conditions lowering to MVFR/IFR.

Another round of tropical rains and scattered thunderstorms will
develop this afternoon into this evening, before tapering off
overnight tonight. There is a risk for strong to severe
thunderstorms, with this risk greatest south of a KBUF-KROC-KFZY
line. The main threat would be strong wind gusts. MVFR/IFR
conditions will continue tonight.

Outlook...

Thursday...Improvement to MVFR/VFR with leftover scattered showers.
Friday...Mainly VFR with a low chance of showers and thunderstorms
across the Southern Tier/Finger Lakes.
Saturday...Mainly VFR with a low chance of showers and thunderstorms
well inland from the lakes.
Sunday...Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
Low pressure associated with the tropical remnants of Beryl will
push into Ohio, and this combined with high pressure to the
north will result in a tightening pressure gradient. Northeasterly
winds will increase, especially on Lake Ontario today. Small craft
headlines will remain for the western two-thirds of the Lake Ontario
waters, and the Lower Niagara River as outlined below. There also
will be several rounds of rain with embedded thunderstorms. Some
storms may produce gusty winds.

The pressure gradient will weaken tonight as the remnant low weakens
with winds diminishing.

Beryl`s remnant low will exit northeast across southern Ontario
Thursday with winds shifting to southwest and freshening to 15 to 20
knots with waves possibly reaching 4 feet on the eastern end of
Lake Erie.

Quiet marine conditions are expected to return Thursday night and
persist into the weekend as high pressure build into the eastern
Great Lakes.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement from 2 PM EDT this afternoon through
     late tonight for NYZ001.
     Flood Watch from noon EDT today through this evening for
     NYZ006>008.
MARINE...Small Craft Advisory from 11 AM this morning to 11 PM EDT this
         evening for LOZ030.
         Small Craft Advisory until 2 AM EDT Thursday for LOZ042-
         043.

&&

$$

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