033
FXUS61 KBUF 150759
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
359 AM EDT Thu Aug 15 2024

.SYNOPSIS...
High pressure draped across the central and eastern Great Lakes will
bring fair dry weather to much of the area today...with just a few
isolated to widely scattered showers and storms possible at times
across the North Country. The high will then exit to our east tonight,
paving the way for a large, slow moving storm system to affect our
region from Friday afternoon through the weekend. The most unsettled
conditions will be Saturday and Sunday...when we can expect occasional
showers and scattered thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today surface high pressure will remain nearly stationary across
the central and eastern Great Lakes...and will provide continued
fair dry weather to western New York. Meanwhile further east...the
eastern Lake Ontario region will remain on the western fringes of
the upper low over the Canadian Maritimes. Spotty showers and
thunderstorms that developed overnight across the North Country
will drift southward and wind down early this morning...before the
combination of daytime heating and another disturbance rotating
around the backside of this low bring the chance for a few more
isolated to widely scattered showers and thunderstorms this
afternoon...with the best chances of these found across Lewis
county. Otherwise it will be a little warmer than yesterday...with
highs ranging from the upper 70s across the higher terrain and along
the southern/eastern shores of Lake Ontario to the lower to mid 80s
elsewhere.

Tonight the axis of the surface high will drift east into central
and eastern New York...while weak ridging builds in aloft. Coupled
with nocturnal stabilization...this will bring an end any lingering
convection across our far eastern zones...with a dry and quiet night
otherwise expected. Later on in the night some high clouds should
begin to arrive across far western New York...with some patchy
valley fog again becoming possible across the Southern Tier.
Overall...low temps will be a touch milder than those of the
previous night...ranging from the mid 50s across the interior of
the Southern Tier and North Country to the upper 50s to mid 60s
elsewhere.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
The longwave pattern across the CONUS will amplify over the weekend
as a ridge builds over the Rockies, forcing a downstream trough to
carve out over the Great Lakes, Ohio Valley, and New England. The
digging trough and ample moisture will bring an extended period of
unsettled weather starting Friday night and lasting through early
next week.

Friday, a narrow ridge surface and aloft will drift slowly east from
the eastern Great Lakes to the Mid Atlantic, sandwiched between a
closed low moving into the upper Great Lakes and another over the
Canadian Maritimes. The wedge of dry air and subsidence will keep
dry weather in place for much of Friday, with a chance of a few
spotty showers and thunderstorms later in the afternoon or evening
across Western NY as height falls start to spread east across the
Great Lakes. Friday will be quite warm, with highs in the mid 80s
for lower elevations and around 80 for higher terrain.

Friday night, the initial push of height falls, DPVA, and moisture
transport supported by a 30+ knot low level jet will gradually cross
the area from west to east, likely producing an area of showers and
a few scattered thunderstorms first in Western NY, and then
overnight from the Genesee Valley eastward.

Saturday through Sunday, the closed low over the upper Great Lakes
will move slowly east, becoming and open wave by late Sunday over
the eastern Great Lakes. A weak surface low vertically stacked
beneath the mid level feature will also move slowly east across the
Great Lakes. Plenty of moisture will be available with PWAT values
averaging 1.5"-1.75" both weekend days. Height falls and diffluent
mid/upper level flow will continue to gradually spread east across
the area, with enhanced periods of ascent from difficult to time and
place convectively generated vorticity maxima. The forcing and
moisture will bring an unsettled weekend, with occasional showers
Saturday through Sunday. There will be a chance of thunder much of
the time, but the coverage of thunder should generally peak in the
afternoon and evening each day as diurnal instability develops.

PWAT values are not overly high, but nonetheless the persistence of
the pattern and moisture suggest some potential for locally heavy
rainfall both days, especially in areas where convection develops.

Temperatures will pull back a little over the weekend, with highs
both days in the 75-80 degree range for lower elevations and low to
mid 70s for higher terrain. It will be muggy, with dewpoints in the
65-70 degree range much of the time.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
The very slow moving mid level trough will linger across the eastern
Great Lakes Sunday night through Monday. The weakening surface low
approaching the eastern Great Lakes Sunday night will give way to
weak secondary cyclogenesis along the New England Coast Monday. There
will still be more than ample forcing and moisture to produce
occasional showers Sunday night through Monday across the eastern
Great Lakes. Thunder chances will gradually wane from northwest to
southeast as a cooler and more stable airmass arrives behind the
slowly advancing cold front.

The mid level trough axis will finally drift east of our longitude
later Monday night and Tuesday, with the plume of deeper moisture
gradually moving off the eastern seaboard. This will bring a return
to mainly dry and seasonably cool weather for the middle of next
week.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Fair dry VFR weather will prevail across the majority of the region
today...with two exceptions. The first will be some localized
reductions to IFR/MVFR in patchy valley fog across the Southern Tier
early this morning. The second will be brief localized restrictions
in some widely scattered showers and storms across the North Country
early this morning...and again this afternoon and early this evening.

Tonight will then feature fair dry weather...with some high clouds
beginning to arrive across far western New York late. Some patchy
valley fog/MVFR vsbys will also become possible across the Southern
Tier again overnight.

Outlook...

Friday...VFR...with scattered afternoon showers and thunderstorms/
localized restrictions from a KROC-KDSV line westward.
Saturday and Sunday...MVFR to IFR with occasional showers and
thunderstorms.
Monday...VFR to MVFR ceilings with scattered to numerous showers and
possible thunderstorms.

&&

.MARINE...
High pressure draped across the central and eastern Great Lakes will
maintain quiet conditions on Lake Erie and Lake Ontario today...with
the weak pressure gradient supporting the development of lake breeze
circulations this afternoon.

A modest southeasterly to southerly flow will then develop later
tonight and Friday as a warm front approaches the region...however
wind speeds should remain less than 15 knots. Following the warm
frontal passage...a general south to southwesterly flow should then
ensue for the weekend...though winds should again generally remain
below 15 knots.

Of greater concern to marine interests will be the potential for
scattered thunderstorms with locally higher winds and waves...with
this beginning Friday afternoon across Lake Erie and western Lake
Ontario...then spreading east across the remainder of the region
over the weekend.

&&

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

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...JJR
MARINE...JJR