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421
FXUS61 KBUF 211753
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
153 PM EDT Tue May 21 2024

.SYNOPSIS...
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Mid-summer warmth will continue this afternoon with well above
normal temperatures and elevated humidity levels. With the very warm
conditions and humidity it will also support some showers and
thunderstorm well inland from the lakes. A greater threat for
showers and storms arrives Wednesday as a cold front approaches the
region. Cooler more comfortable weather can be expected Thursday
into the first part of the Memorial Day weekend.
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&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Mid-summer warmth will continue today with temperatures more typical
of July than late May. Highs this afternoon will again reach the mid
to upper 80s. We even potentially could hit 90F in a few spots,
especially in the Genesee Valley. The Watertown record high of
83F/2022 will certainly be in jeopardy, but warmer records in the
90s for Buffalo and Rochester look to be safe.

Later this afternoon a shortwave will pass by to our north combined
with the potential for a lake breeze boundary or two will trigger
some scattered convection. The main coverage area will be well
inland from the cooler stable lakes, especially from the
Southern Tier northeast across the Finger Lakes into the North
Country. A few more robust storms are possible across the North
Country closer to the passing shortwave.

Tonight...with the loss of daytime heating most showers and storms
will fall apart with dry weather expected across the region. Muggy
(dwpts in the 60s) and mild night with mercury reading found in the
mid to upper 60s by sunrise.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Well within the warm sector of a system tracking across the Great
Lakes, Wednesday will be another warm day with increasing humidity.
Out ahead of an approaching cold front, a pre-frontal trough will
push across the forecast area from around lunchtime through the
early evening hours. CAPE values for Wednesday afternoon approaching
2,000 J/kg, especially south of Lake Ontario. Instability levels
combined with the trough will result in showers and thunderstorms
across the area, especially inland from the lakes. The Storm
Prediction Center does have most of the area under a `Slight Risk`
for severe thunderstorms on Wednesday. With instability across the
area, showers/thunderstorms will be possible ahead of the trough as
well as daytime heating increases through the morning. Large scale
shear values seem to be a bit on the lower side with guidance
suggesting less than 30 knots of shear during the peak, HOWEVER, a
remnant Mesoscale Convective Vortex (MCV) will be tracking
into/across the area, and these system tend to have increased shear
within the system itself that modeling has a hard time to pick up on
sometimes. Luckily this is a decaying MCV that should hopefully
limit the severe potential vs a more organized system. DCAPE values
nearing 750 J/kg will support the potential for strong wind gusts.
Temperatures on the day will warm to the lower 80s over the higher
terrain to near 90 for the lower elevations.

Wednesday night, showers and some thunderstorms will linger into the
mid-evening  hours over the eastern portions of the area as the
trough is exiting the region. There should be a break in the showers
for most of the night ahead of the cold front. With daytime heating
not in play, instability levels will lower overnight. As the cold
front crosses the region during the second half of the night and
toward daybreak on Thursday some showers will be possible,
especially inland from the lakes. There may be just enough lingering
instability along with forcing from the front to cause a few
thunderstorms. Shear values do increase some with the frontal
passage, but not expecting much in the way of thunderstorm
potential. Low temperatures on Wednesday night will drop to the low
to mid 60s.

Thursday and Thursday night, some showers will linger into the
morning, mainly for the eastern third of the area. Clouds will
decrease from northwest to southeast behind the departing cold front
and as drier air moves into the region. A cooler day on Thursday
with afternoon highs mainly in the upper 60s to upper 70s from the
higher terrain to the lower elevations respectively. Thursday night,
lows will dip down to the low to mid 50s across the entire area.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Dry conditions to start the period before a trough and sfc low track
across the Ohio Valley and Great Lakes. A warm front tracking toward
the region out ahead of the sfc low will start to increase showers
potential for Friday night. Showers continue through Saturday night
as a few disturbances track northeast around a weak trough over the
Great Lakes.

Fair conditions expected for Sunday as high pressure tracks across
the region.

The next round of showers approaches late Sunday night/Monday
morning as another trough and sfc low track across the region.

Temperatures for the period will be in the low to upper 70s for most
of the area with the cooler temperatures across the higher terrain
and the warmer temperatures over the lower elevations.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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Diurnal cu fields developing inland from the lakes this
afternoon. Uncertain on thunderstorm potential this afternoon
and early this evening. Scattered convection will develop ahead
of shortwave crossing north of Lake Ontario. Expanding cu field
from the Southern Tier into the Finger Lakes will also form
some convection. Given hi-res guidance keeping much of the
convection east and south of the area, confidence not high
enough to place a mention of TSRA in at KJHW, KROC and KART.
High confidence that lake shadowing will occur at KIAG and KBUF.

Any convection will die out quickly this evening leaving
widespread VFR conditions, with enough southerly graident flow
in the boundary layer to make it difficult for fog formation.

Outlook...

Wednesday...VFR/MVFR. Showers and thunderstorms likely.
Thursday...Mainly VFR. A chance of showers.
Friday...Mainly VFR.
Saturday...Restrictions possible. A chance of showers and
thunderstorms.
Sunday...Mainly VFR. A chance of showers and thunderstorms.
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&&

.MARINE...
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South winds will continue up to 15 knots through tonight as a
cold front to our west begins to approach the eastern Great
Lakes, with conditions remaining below small craft levels.

Low pressure will send a cold front into the eastern Great
Lakes on Wednesday, but winds and waves look like they will
remain below small craft conditions for the rest of the week.
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&&

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

&&

$$

SYNOPSIS...AR/TMA
NEAR TERM...AR/TMA
SHORT TERM...SW
LONG TERM...SW
AVIATION...TMA
MARINE...AR/TMA