307
FXUS61 KBUF 061815
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
215 PM EDT Sun Jul 6 2025

.SYNOPSIS...
Ahead of a slow-moving cold front, hot and humid air
will flow into the region with many areas reaching Heat
Advisory criteria this afternoon. The front will bring showers
and thunderstorms to the region Monday with locally heavy
rainfall possible. Mostly dry and more comfortable weather for
Tuesday through Wednesday before becoming unsettled again in the
latter half of the week.

&&

.NEAR TERM /THROUGH MONDAY/...
Southwesterly flow behind a departing sfc high and ahead of an
approaching sfc low and cold front will result in hot and humid
conditions today. Heat index/apparent temperatures will reach 90+
degrees Fahrenheit today for most of the forecast area, with the
usual warmer locations reaching the mid to upper 90s. These areas
have a Heat Advisory in place from 11am until 8pm this evening, this
includes all of the southern Lake Ontario shoreline counties plus
Genesee, Livingston and Ontario counties. A few scattered
showers/storms will also be possible today, mostly confined to the
North Country where a LLJ will cross the area, providing some
forcing to initiate a few showers/storms. For the rest of the
forecast area, can expect mainly dry weather today. With a
tightening pressure gradient over the region and the above mentioned
LLJ, breezy conditions will be possible through the first part of
the evening.

Tonight, as the sfc low, pre-frontal trough and cold front approach
the region, shower and thunderstorm potential will increase some
across the northwestern portions of the area toward daybreak.
Guidance is still split with the potential for showers/storms within
a few hours of daybreak, with global models and regional models
still bringing showers/storms close to the extreme northwestern
portion of the forecast area by around 12Z. CAM guidance is further
west with the showers by 12Z with little to no potential for showers
to move into the forecast area through the tonight period. It will
be a warm and humid night with lows only dropping down to the upper
60s to mid 70s, with some higher spots down to the mid 60s.

Monday, the sfc low will track northeast across southern Ontario and
into southern Quebec through the day. Its trailing cold front will
track toward and cross the forecast area during the late morning and
through the afternoon. The pre-frontal trough associated with the
system looks like it will weaken and get taken over by the cold
front early in the day, just west of the forecast area. This is what
the higher resolution guidance is trending with and the reason why
they are also trending drier for the first half of the morning on
Monday. The front will track through the area in pieces with the sfc
portion moving into far WNY by the mid to late morning time and
track through the eastern portions of the forecast area through the
late afternoon. The rest of the front will lag behind by a few
hours.

Showers and thunderstorms will be possible ahead of the front as the
warm and moist airmass remains in place, and as any remnant form of
the pre-frontal trough moves into the area and interacts with lake
breeze boundaries. Most of the shower and thunderstorm activity
should remain just ahead of or along the cold front as it crosses
the area. With high PWat values of around 2.00", weak flow aloft and
near parallel flow with the front, heavy rain is expected within
some of the showers and thunderstorms with the potential for
training of thunderstorms. This will increase the potential for
areas of localized flooding in some areas, with the greatest
potential expected for areas of the western Southern Tier and the
western/northern Finger Lakes. As a result of the heavy rain
potential, there is a `Marginal Risk` for excessive rainfall on
Monday for the entire area, but the best potential is expected for
areas mentioned above. There is also a `Marginal Risk` for severe
thunderstorms on Monday across the entire area. While CAPE values
look favorable for thunderstorms (1,000+ J/kg), shear looks
generally weak, but a few storms may produce some gusty winds. DCAPE
values of around 500-750 J/kg would support this potential for some
gusty winds that will be possible. Temperatures on Monday will be a
little cooler than today with highs in the mid 80s for far western
NY and the North Country, with areas of the western and northern
Finger Lakes remaining a bit warmer in the upper 80s to low 90s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
General broad troughing will set up across the Great Lakes Monday
night and last through much of the week. Heading into Monday night,
a cold front will be in the midst of crossing the eastern portions
of the forecast area with a weak shortwave trough crossing overhead
of the lower Great Lakes nudging it along. As such, this will result
in the last few convective showers to exit the area early in the
evening, before cooler and drier air arrives late in the night.

While the general troughing pattern remains overhead Tuesday and
Tuesday night, zonal flow with in the base of the broad trough will
support a bubble of surface high pressure to ridge into the region
from the Ontario Province. With high pressure overhead, mainly dry
weather will persist, though a few spotty showers will be possible
along the far east/southeastern portions along the periphery of the
surface high. Meanwhile, temperatures will be more seasonable
Tuesday with highs int he upper 70s to low 80s.

The next more defined shortwave trough will travel through the base
of the longwave trough Wednesday and Wednesday night, sliding across
central Great Lakes. While high pressure will most likely dominate
across the lower Great Lakes Wednesday, a surface low passing east
along a stationary front across the Ohio Valley will introduce a
slight chance for a few showers and thunderstorms Wednesday
afternoon across the western Southern Tier before spreading
northward across the remainder of the area Wednesday night.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The later half of the week, will feature a longwave trough axis
overhead of the central Great Lakes to traverse east into New
England by this weekend. Overall this will continue to support the
chance for showers and thunderstorms Thursday through Friday. Then
as the next trough enters the northern Great Lakes Saturday, the
ridge axis of a skinny ridge will slide east across the lower Great
Lakes this weekend. Guidance continues to struggle with the timing
of these features for the weekend and therefore the current forecast
resembles the National Blend, keeping a chance for rain showers and
afternoon thunderstorms Saturday and Sunday.

Otherwise with the troughing pattern overhead, temperatures will be
near to slightly above average early to mid July.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Mainly VFR through tonight. Some afternoon fair weather clouds
across the area, but limited to FEW/SCT at around 5kft. A LLJ over
the Niagara Frontier and the North Country is causing some gusts to
around 25 kts this afternoon. Both wind and cloud will
weaken/dissipate this evening.

Monday, mainly VFR to start the day, but flight conditions will
deteriorate through the day. First with showers and thunderstorms
ahead of and along a cold front that will cause heavy rain at times.
The best chance for heavy rain is expected mainly for the inland
areas south of Lake Ontario, but at least a heavy downpour for any
location in the forecast area is possible. Flight cats in heavier
downpours down to MVFR expected and even IFR possible at times,
mostly for VSBY, but lower CIGs also possible. CIGs will then lower
to lower end MVFR and some IFR by the late afternoon as the cold
front crosses the area in pieces.

Outlook...

Monday night...Mainly MVFR to IFR with decreasing chances for
showers and thunderstorms.

Tuesday and Wednesday...Mainly VFR.

Thursday...A chance of showers and thunderstorms with MVFR
restrictions possible.

Friday...early restrictions should improve to VFR.

&&

.MARINE...
A tightening pressure gradient over the lakes today between high
pressure in the western Atlantic and a cold front to the northwest
has led to breezy southwest winds in some areas approaching SCA
levels. Confidence is low to moderate as the setup looks very
marginal, though the two main areas of concern are the St. Lawrence
and Upper Niagara rivers, as the relatively cool lakes should
inhibit mixing of stronger winds across the open waters. Winds will
also be breezy over the southwestern end of Lake Ontario, though the
offshore direction should preclude the need for SCA headlines. While
strong winds aloft will remain overhead tonight, limited mixing
should allow sfc winds to diminish this evening.

Otherwise, a few thunderstorms will also be possible across or just
north of the St. Lawrence River through the day today. More
widespread chances for tstorms across the waters will arrive Monday,
before the cold front finally moves through the region later Monday.
Post-frontal winds will become northwesterly into early Tuesday,
though sub-SCA conditions are expected through the rest of the week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Heat Advisory until 8 PM EDT this evening for NYZ001>006-011-
     013-014.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
         Small Craft Advisory until 8 PM EDT this evening for
         SLZ022.

&&

$$

SYNOPSIS...PP
NEAR TERM...SW
SHORT TERM...EAJ
LONG TERM...EAJ
AVIATION...SW
MARINE...PP