743
FXUS61 KBUF 030450
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1250 AM EDT Wed Jul 3 2024

.SYNOPSIS...
After two spectacular days of weather...it will become uncomfortably
sultry on Wednesday with most sites across the lake plains reaching
close to 90. Meanwhile...our stretch of rain free weather will
come to an end later this afternoon and evening when a weak cold
front will generate some showers and drenching thunderstorms.
While most areas will then be rainfree for the Fourth of July...
there will be only minimal relief from the heat and humidity.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
While generally fair dry weather will be in place for most areas
overnight...it will be cloudy and notably warmer than recent
nights with daybreak temperatures averaging some 10 to 15 degrees
higher than recent nights. The passage of a warm front will not
only support a wealth of alto- cu cloud cover...but could also
allow for some sprinkles. A ton of dry air between 5-10kft though
should enable most of the pcpn to evaporate before reaching the
ground.

Wednesday is then GUARANTEED to be very warm and moderately humid,
as a deepening southerly flow increases ahead of an approaching cold
front. This will prompt Tds to return to the mid and upper 60s,
while PWAT values will surge to around 2 inches. As is most often
the case during the summer, the approaching cold front will be
preceded by a pre-frontal sfc trough. This will help to initiate
some thunderstorms over the Southern Tier and western Finger Lakes
during the afternoon, then more widespread convection can be
expected late in the day into the evening with the cold front.
Forecast bulk shear of 40kts or so will increase the risk for
organized convection that could produce gusty winds, particularly
over southern areas. SPC highlights the most favored area for severe
weather to be well to our southwest, in the vcnty of the Ohio
valley.

Temperatures on Wednesday will top out between the 85F to 90F range,
with the higher end of that range expected for the lake plains where
heat index values will approach the mid 90s.

Wednesday night, showers and storms will dwindle as the cold front
settles south of the Lower Lakes overnight. Otherwise, not overly
cool behind this front with lows generally found in the 60s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Weak cold frontal boundary will continue to press southeast through
the region Thursday. A few showers or a thunderstorm will be
possible closer to the New York/Pennsylvania state line, especially
if the front slows down and does not clear the area by afternoon.
Otherwise drier air advecting in behind the front will keep the
remainder of the area dry. Not much of a push of cooler air
behind the front, so temperatures Thursday still will be warm
with highs mostly in the lower to mid 80s, but humidity levels
should slowly drop off through the day.

Dry conditions should continue Thursday night with the boundary
to our south, although the boundary will start to makes its way
northward as a warm front with at least some small risk for
some convection working back into the Southern Tier late
Thursday night.

Warm frontal boundary will continue to make its way northward
through the region Friday with temperatures following suit with
highs in the mid to upper 80s, with the warmest heat index
values approaching 90F. With the very warm and humid air mass
in place, a few showers and thunderstorms may develop, mainly
across western New York.

A better convective signal exists for the Friday night period,
anchored by the arrival of organized forced ascent associated
with a mid level wave shortwave tracking eastward from the upper
Midwest into the Great Lakes.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The low pressure system that brought widespread showers Friday night
will become vertically stacked across the upper Great Lakes by
Saturday morning, causing it to weaken as it tracks northeast into
Quebec. The system`s cold front will be in the process of marching
east through western NY Saturday morning, with a mid/upper level dry
slot following in its immediate wake. While showers and possibly a
few thunderstorms should be ongoing Saturday morning across the
North Country Saturday ahead of the front, confidence is lower in
whether or not the dry slot will extend far enough north to bring a
period of drier weather to our eastern zones by the afternoon. Have
therefore undercut NBM PoPs by a small amount across WNY in the
morning to better indicate the expected dry interlude, before
additional synoptic moisture out ahead of the main trough axis
combines with diurnal heating in the afternoon to increase
shower/thunderstorm chances. While temperatures Saturday will likely
depend on the exact timing of the front in the morning, highs are
expected to generally range from the upper 70s to the mid 80s,
warmest across the Finger Lakes region and in the Genesee Valley.

The mid-level trough axis and moisture starved secondary cold front
will swing through the region Saturday night. An area of high
pressure subsidence building in its wake will lead to sharply
decreasing chances for showers and thunderstorms from west to east
overnight, with just a low-end chance lingering across the North
Country by Sunday morning. Lows Saturday night will range in the 60s
with lower overall humidity.

Surface high pressure centered to our south along with a flattening
mid-level ridge moving through the Great Lakes will then crest over
our region through Sunday night, ensuring fair dry weather to cap
off the weekend. Highs Sunday will be comfortable in the 70s to low
80s, with lows Sunday night in the low to mid 60s.

Unsettled weather returns for the work week as weak high pressure is
gradually replaced by yet another broad, weakening trough across the
Great Lakes. While Monday is expected to be mainly dry as the
eastern Great Lakes looks to be sandwiched between areas of deeper
moisture to our west and along the East Coast, some diurnal shower
activity can`t be completely ruled out. The next large scale system
will come sometime Monday night into Tuesday as a shortwave trough
moves out of the Ohio Valley, partially phasing with the longwave
trough over the Great Lakes as it moves into the forecast area.
Could see PoPs being raised into lkly territory for parts of the
area with subsequent updates as timing discrepancies are better
refined, but at this range will stick to Chc. Otherwise, the
position of the high to the east should give temps a solid boost
Monday back into the mid and upper 80s across the Lake Plains,
cooling off again slightly for Tuesday.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will be in place overnight...although a passing warm
front will support a wealth of alto-cu. Sfc winds will be light.

VFR conditions will continue Wednesday morning before a weak cold
front will cross the area late in the afternoon and first part of
Wednesday night. This frontal passage will support some showers and
thunderstorms. Cigs in the wake of the front will drop to MVFR for
many areas late Wednesday night...mainly south and east of a line
from Buffalo to Rochester.

Outlook...

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.
Sunday...VFR

&&

.MARINE...
A warm front will work across the lakes overnight. Winds will pickup
late out of the south pushing higher wave action off shore as we
move into Wednesday.

A cold front will approach the region Wednesday. Winds will veer to
the southwest ahead of the cold front.  While fair weather will
remain in place through at least midday, there will be an increasing
risk for thunderstorms in the afternoon and evening.

In the wake of the cold front, fair weather will return to the
region later Wednesday night with subsiding southwest breezes.

Looking ahead to the Fourth of July, gentle to moderate winds will
be in place throughout the region. These winds will be from the
southwest on Lake Erie and primarily from the west on Lake Ontario.

&&

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

&&

$$

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