028
FXUS61 KBUF 221856
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
256 PM EDT Sat Jun 22 2024

.SYNOPSIS...
Warm and humid weather will continue this weekend. An oscillating
frontal boundary will support showers and thunderstorms this
weekend with the risk of torrential downpours and severe weather.

&&

.NEAR TERM /THROUGH SUNDAY/...
A surface boundary was positioned just south of Lake Ontario this
afternoon. North of the boundary plenty of clouds along with
lingering scattered showers. South of the boundary within the warm
sector, dewpoints in the 70s and temperatures well into the 80s
with a few near 90 degree readings. SPC meso analysis showing
surface based CAPES have increased to over 2000 J/KG with
convection starting to fire along the Lake Erie lake breeze from
northwest Pennsylvania into the western southern Tier. Lastest
HRRR/HREF suggesting convection will continue to develop across
the Southern Tier before growing northeast into the Finger Lakes
through the rest of the afternoon. Shear profiles are less than
favorable, so think this activity stays below severe limits, but
will likely see tropical downpours along with some gusty winds
and perhaps some small hail.

Convection should die off this evening as diurnal instability wanes.
The surface boundary will gradually lift north tonight as a surface
low strengthens over the central Great lakes. This will place more
of the region within the warm sector. Some scattered showers may
continue close to the boundary over northern portions of the area.
Isolated convection is possible within the warm sector. Some
patchy fog may occur in areas which received rain during the
day. Overnight temperatures will be muggy and generally in the
lower to mid 70s, with some upper 60s across the Southern Tier
and east of Lake Ontario.

An active weather day is expected on Sunday, especially during the
afternoon. A potent upper shortwave and associated deepening surface
cyclone tracking from the central Great Lakes along the
international border. A pre-frontal trough will work into the
region early in the day ahead of the main of the cold front
which tracks into the region late in the day.

There may be two rounds of convection, first with the pre-frontal
trough and then ahead of the cold front later in the afternoon.
Surface instability will certainly be present with SBCAPES forecast
to be near 2000 J/KG. Shear profiles become increasingly favorable
with around 35 knots of flow at 850 mb and near 50 knots at 500
mb, with some turning with height allowing hodographs to
lengthen with time. SPC has maintained a Slight Risk for severe
storms for much of the area inland from the lakes. Main threat
looks to be damaging winds, with a lesser threat of large hail,
but with the lengthening hodographs could see an isolated
supercell. Heavy rain potential is there with high atmospheric
moisture content, but the convection should be progressive
making the flash flood threat more limited.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A mid-level shortwave rippling through the zonal flow aloft and
corresponding surface reflection (997-999mb low) passing to our west
and northwest, will drag a cold front through the Lower Lakes on
Sunday. Associated height falls with the pre-frontal trough will
`likely` encourage some measure of shower and thunderstorm activity
ahead of this cold front. Guidance continues to suggest that the pre-
frontal trough will arrive before the occurrence of peak heating
between 12Z-15Z for far WNY. Even so...the cold front may still
spark additional storms as it rolls east through the forecast area
in the afternoon. Right now...the best chance for organized storms
looks to be from the S. Tier/western Finger Lakes region ENE into
the North Country and St. Lawrence Valley. Given ample shear (0-6km,
40 knots) any of the stronger cells will `likely` have the potential
to produce damaging winds and even an isolated tornado. SPC has
highlighted the above mentioned areas in a slight risk for severe
weather. Lastly...storms will also be capable of producing
torrential rainfall given PW values in the neighborhood of 1.75-2.00
inches.

Otherwise...outside of the convective activity it will become quite
breezy, with wind gusts up to 45 mph. The strongest winds will be
felt northeast of Lake Erie across the Niagara Frontier. Highs on
Sunday will range from the upper 70s across the higher terrain to
the low/mid 80s elsewhere.

Sunday night...with the departure of the cold front showers and
thunderstorms will quickly decrease in coverage. However...there may
still be some showers that linger east of Lake Ontario/St. Lawrence
valley.

High pressure begins to build in on Monday with increasing
subsidence which will bring about mainly dry weather for most
locales. Although an isolated shower still can`t be ruled out,
especially east of Lake Ontario. The best part will be the notably
cooler airmass and less humidity. Highs on Monday will be in the 70s
near 80F in spots.

Surface high pressure slides overhead Monday night and then begins
to sink south towards the Mid-Atlantic on Tuesday ahead of the next
cold front. We should see mainly dry weather Tuesday before chances
for showers and storms increase through Wednesday. More on that in
the long term disco.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Confidence is low in timing and coverage of showers/thunderstorms
associated with an approaching front for Tuesday night and Wednesday.
Long range guidance is in poor agreement on the evolution of a
shortwave expected to slide east across Southern Ontario and the
Great Lakes. Greater chances for showers and thunderstorms will
potentially arrive Wednesday as a ~982mb surface low tracks across
northern Quebec, sending its elongated cold front through the
Northeast. While timing of this front and its associated prefrontal
trough remain in question and thus lend lower confidence in how
convection will ultimately unfold Wednesday...The system is expected
to tap into a deeper plume of GOMEX-based moisture with PWATs
potentially climbing to near 2" as it approaches. Thus, any storms
that develop and move through the region should have the potential
to bring locally heavy rains.

The primary cold front should move through the region Wednesday
night, with increasing subsidence and a drier airmass allowing
shower/thunderstorm chances to decrease from west to east in its
wake. As much of the Northeast sits within the post-frontal airmass,
temperatures will be notably cooler Thursday and Thursday night,
with highs in the low/mid 70s and lows in the 50s and upper 40s
respectively. Dry weather should then last through the end of the
week with moderating temperatures as surface high pressure moves
over and east of the region.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
A frontal boundary across northern portions of the area will waver
northward through tonight. While CIGS today north of the boundary
(KART) will be mainly MVFR, all other terminals will be VFR south of
the boundary. The main impact through this evening will be the
threat for convection, particularly across the western Southern
Tier into the Finger Lakes. Low confidence in overall coverage,
so left out of airfield forecasts, except for KJHW where the
proximity to the Lake Erie lake breeze places a bit more
confidence at that location for at least a VCTS mention.

Chances for showers and thunderstorms will continue tonight
inland from the lakes. Patchy fog is also possible where rain
occurred during the day, but low confidence where restrictions
will occur.

Outlook...

Sunday...VFR/MVFR. Showers and thunderstorms likely.
Monday...Mainly VFR. A chance for afternoon and evening
thunderstorms inland from the lakes.
Tuesday...Mainly VFR conditions.
Tuesday night and Wednesday...MVFR/VFR with a chance for showers and
thunderstorms.
Thursday...Mainly VFR.

&&

.MARINE...
Light winds and minimal wave action is expected to continue across
the lower lakes through tonight.

A cold front will approach the region Sunday with increasing
southwest winds which will likely bring a period of small craft
conditions, especially on the east end of Lake Erie. A round or two
of thunderstorms Sunday will bring the potential for locally strong
winds and waves.

Northerly flow behind the cold front will then bring continued
choppy conditions to the lakes through Monday. High pressure builds
in late Monday with diminishing winds and waves for Tuesday.

&&

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

&&

$$

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