362
FXUS61 KBUF 032258
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
658 PM EDT Wed Jul 3 2024

.SYNOPSIS...
A weak cold front will move across the area tonight and generate a
few showers and scattered thunderstorms with uneven coverage. Most
of the showers will taper off and end late tonight and early
Thursday. While most areas will then be rainfree for the Fourth of
July, it will remain very warm and humid for the holiday. The next
round of widespread showers and a few thunderstorms will then arrive
Friday night.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
A broad longwave trough and attendant surface low over northern
Ontario Province this afternoon will shift northeast into Quebec
across Hudson Bay later tonight. Additional shortwave energy well to
the south of this low is moving across southern Ontario in tandem,
with its associated cold front currently across Michigan and the
central Great Lakes. Deep SSW flow and moisture advection within the
warm sector of this system is causing a rather sultry afternoon to
unfold with much more heat and humidity compared to the last couple
of days. Temperatures have climbed well into the 80s in most spots
with corresponding Tds in the upper 60s to near 70.

A weak prefrontal trough will slowly work its way through the
eastern Great Lakes from west to east this evening, acting as a
focus for weak/sporadic showers and a few thunderstorms. Weak DPVA
and moisture transport/convergence supported by a 40knot low level
jet will allow for a few showers and thunderstorms to continue into
the night along the advancing trough, and a few more showers may
develop overnight as the weak cold front moves southeast across the
area. Overall, expect the best coverage of rain to be found across
the Southern Tier, Finger Lakes, and east of Lake Ontario, with more
spotty coverage from the Niagara Frontier to Rochester.

Forecast profiles and SPC objective mesoanalysis shows moderate CAPE
and shear available, but very poor mid level lapse rates are proving
difficult to overcome as developing updrafts quickly weaken as they
encounter the unfavorable thermodynamics of the mid levels. PWAT
values are around 2" so any storms that develop will produce
brief/local downpours, but the progressive nature of the system and
disorganized nature of convection should prevent anything
problematic.

Otherwise...It will be a rather muggy night with lows in the upper
60s to low 70s and plenty of residual humidity.

Shower coverage will taper off late tonight into early Thursday
morning as the frontal boundary moves south and stalls across
Pennsylvania. Mainly dry weather will then persist through
Independence Day as the better moisture and forcing for precipitation
remains well to our south, but an isolated shower or thunderstorm
can`t be ruled out across the Southern Tier and southern Finer Lakes
region. With very little of an airmass change on the `cooler` side
of the boundary, expect another warm and humid day, though not
quite as oppressive. Highs will range in the low to mid 80s with
dewpoints still well into the 60s.

Mainly dry weather for Thursday night as weak surface high pressure
remains over the region. Light winds at the surface and aloft will
make any firework smoke slow to clear. Lows will again be warm,
ranging in the mid to upper 60s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
Potent southeasterly flow will encompass the area on Friday. This
flow will strengthen through the afternoon and evening hours,
eventually turning more southerly. Off the deck, consensus 850 hPa
temperatures surge toward +18 to +19C and momentum mixes through the
boundary layer below that level. This combined with southeasterly
flow, which relegates the lake influence to almost nil across the
majority of the area, should all for temperatures to skyrocket on
Friday. Highs should jump toward 90F, especially along the Lake Erie
shoreline, Buffalo area, and the Genesee Valley.

Friday`s warmth will be short-lived as the brisk southerly flow
comes in advance of a southwesterly low-level jet nose that nudges
into the area by Friday evening. This combined with a right entrance
of an upper jet streak and solid DPVA should work on the remaining
instability from the hot day on Friday to trigger widespread showers
and thunderstorms Friday evening in WNY that spread eastward
overnight.

Organized ascent slowly translates across the area into Saturday,
when the North Country should be the shower focus for the early half
of the day at least. The remainder of the area looks to largely move
into the mid-level dry slot of the system that will be occluding by
that juncture over the northern Lake Huron region. Thus, deep layer
dry advection and modest cold advection should at least temporarily
cut off rain chances from west to east as the afternoon ensues on
Saturday. Likewise, temperatures will be falling back in cold air
advection to a bit below normal across at least the western half of
the area.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Surface ridging and drier air moving in behind the cold frontal
passage gives fairly high confidence that the area will see dry
weather through Monday. Showers and thunderstorms return to the
forecast for the Tuesday through Wednesday period as a mid level
trough enters the region and a wave of low pressure tracks to our
north bringing a cold front through the region.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
A weak cold front will move across the area tonight and generate a
few rounds of showers and scattered thunderstorms. The best coverage
of rain is expected to be across the Southern Tier, Finger Lakes,
and east of Lake Ontario, with lower coverage from KBUF to KROC.
Thunder has been minimal with this activity so far, but enough
instability lingers into tonight to support a few spotty
thunderstorms.

Mainly VFR will continue through the first half of the night outside
of any brief/local restrictions in heavier showers. Overnight, areas
of low stratus will develop with MVFR CIGS, especially across higher
terrain and over/east of Lake Ontario.

The weak cold front will move southeast of the area Thursday
morning, with any remaining showers and thunderstorms coming to an
end. This will leave mainly dry weather for the rest of the day.
Lingering areas of MVFR stratus in the morning will improve to VFR
by midday.

Outlook...

Friday...Mainly VFR with increasing chances for showers and
thunderstorms.
Friday night...MVFR with showers and thunderstorms likely.
Saturday...Mainly VFR with decreasing chances for showers.
Sunday and Monday...VFR.

&&

.MARINE...
A weak cold front will cross the lower Great Lakes tonight with a
few rounds of showers and widely scattered thunderstorms. A
southwest breeze will persist ahead of this front, with a moderate
chop on the eastern nearshore waters through early tonight.

In the wake of the cold front...fair weather will return to the region
late tonight 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,
becoming locally onshore in the afternoon. Winds will then shift out
of the east Friday, becoming southwesterly again by Saturday when
the another round of SCAs appears likely.

&&

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

&&

$$

SYNOPSIS...Hitchcock/PP
NEAR TERM...Hitchcock/PP
SHORT TERM...Fries
LONG TERM...TMA
AVIATION...Hitchcock
MARINE...Hitchcock/PP