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518
FXUS61 KBUF 201839
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
239 PM EDT Thu Jun 20 2024

.SYNOPSIS...
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Warm and humid conditions continue through most of the weekend, but
not as warm as today. Periods of showers and thunderstorms will also
continue through Monday. Cooler temperatures return to the region
late Sunday and Monday behind a passing cold front.
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&&

.NEAR TERM /THROUGH FRIDAY/...
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The earlier remnant MCV is mostly out of the North Country as of
early this afternoon. A spoke of energy extending southwest from the
MCV has allowed some showers/storms to develop over the Finger
Lakes, just outside of the BUF forecast area. Otherwise mainly clear
across the area as of early this afternoon, especially closer to the
lakes. Some fair weather cumulus is developing inland from the
lakes.

Showers and thunderstorms are expected to develop this afternoon
inland from the lakes as instability increases. The best chance for
showers/storms early on will be along outflow and lake breeze
boundaries that develop over the western Southern Tier. Expected
slower motion and high PWats of around 1.75 inches will result in
some heavier downpours within slower moving storms. This may cause a
few areas of poor drainage flooding and if rain become heavy enough
some flash flooding can`t be ruled out, especially for areas of the
Southern Tier where heavy rain has already occurred the past few
days. Another MCV just north of Toronto will track east, just north
of Lake Ontario this afternoon into the evening. As this MCV tracks
east there is the potential for showers and thunderstorms to develop
south of Lake Ontario later in the afternoon as a spoke or two of
energy tracks into the area. Some shadowing from the lakes will be
possible reducing some of the instability available for the
potential for storms, but further inland from the lakes where
instability will increase showers and storms will be more likely.
The Storm Prediction Center has a `Marginal Risk` for severe
thunderstorms south of Lake Ontario and a `Slight Risk` for severe
thunderstorms northeast of Lake Ontario. The `Slight Risk` are is
primarily for the first MCV going through, but there will also be a
higher severe potential later on with the 2nd MCV tracking nearby.
WPC has a `Marginal Risk` for excessive rainfall due to the
potential for some of the heavier downpours that may occur within
thunderstorms that develop.

Temperatures this afternoon will remain well above normal with highs
in the mid 80s to low 90s. Combined with the moist atmosphere, heat
index values in the mid to upper 90s can be expected for most of the
area, with a few spots reaching around 100. Overall though today
should be a degree or two cooler than the past few days as
temperatures aloft are a bit cooler with the ridge over the region
nudging south and de-amplifying some. This is occuring as a trough
is approaching from the northwest and the interaction between that
and the ridge is causing the flow to go from more of a ridge to
zonal.

Tonight, a slow moving weak frontal boundary will slowly drop
southeast into the area, resulting in continued potential for
showers and thunderstorms. The warm and humid airmass will continue
to support thunderstorms, with the frontal boundary continuing to
weaken, providing only minimal relief, mainly north of where it
stalls. Temperatures tonight will be in the upper 60s to low 70s for
most of the area.

Friday, showers and thunderstorms will continue with the frontal
boundary stalled over the area from west to east. A few showers and
storms in the morning should increase in coverage some as daytime
heating increases instability. Guidance is a bit split on coverage
of showers and how heavy some of the showers will get, but the best
coverage for showers will once again be in the afternoon with the
daytime heating, that is generally agreed on among guidance. Friday
afternoon highs in the low to upper 80s will be coolest to warmest
from the north to the south with the frontal boundary draped west to
east over the area.
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&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
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Friday night, the stalled front across the area will begin to slowly
push north as a warm front late in the night and into the early
Saturday morning. Can`t rule out a stray shower or thunderstorm but
for the most part there should be a break in precipitation Friday
night.

Most models show a weak shortwave passing by to the north which
would cause the front to meander a bit during the day Saturday. The
North Country should stay on the cool side of the boundary. The
shortwave is likely to generate some showers with its passage, but
there`s a lower risk of thunderstorms in the North Country. For the
Western NY, a lot depends on the timing of the shortwave with lower
chances for showers and thunderstorms if it passes in the morning
and greater chances if it`s in the afternoon. High temperatures will
range from the upper 80s near the Pennsylvania border to the upper
70s in the North Country.

Strengthening low pressure tracking across the central Great Lakes
will lift the front back to the north, putting the entire forecast
area in the warm sector. The warm and moist air mass will support
small chances for showers and thunderstorms across Western NY with
showers and storms likely across the North Country which will be
closer to the boundary and any disturbances that track along it.

A 995mb surface low and robust shortwave tracking to our north will
result in a windy day on Sunday with 850mb winds increasing to about
45 knots. This will push a strong cold front across the area which
is likely to produce some thunderstorms with its passage. There will
be ample wind shear in place to support organized convection with
damaging winds possible. Timing will be key, with model consensus
bringing the front through slightly earlier than ideal to produce
storms in far Western NY, with greater risks for storms closer to
Central NY. But this could change in future model runs. Even without
convection it will be windy across the Niagara Frontier where wind
gusts of 45 mph can be expected.
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&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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A cold front will slide east of our area Sunday night, with
lingering showers and thunderstorms tapering off from west to east.
This will be followed by a potent shortwave which will dig across
northern New England on Monday. This will bring increasing chances
for showers and a few thunderstorms across the North Country with
low chances elsewhere which will be further from the disturbance. It
will also be notably cooler and less humid with highs on Monday only
in the 70s.

High pressure will move across the region Monday night and Tuesday,
resulting in rain free and cooler weather. Another shortwave will
pass by well to the north Tuesday with an associated cold front
moving across the area Tuesday night or Wednesday. This will bring
warmer weather ahead of the cold front with a chance of showers and
possibly a thunderstorm. The cold front will then usher in cooler
weather for Thursday. By Thursday highs should only be in the upper
60s to lower 70s. Did hedge below model guidance for high temps
given the cool air mass and recent warm weather included in bias
correction.
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&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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Mainly VFR at area terminals today. Areal coverage of showers and
storms expected to increase later this afternoon, with a risk of
heavy rain and gusty winds.

Tonight...VFR conditions outside of showers and storms. Once again
there will be the potential for some fog in the river valleys of the
S. Tier.

Friday, showers and thunderstorm potential remains across much of
the area, especially inland form the lakes and during the afternoon
hours. Mainly VFR conditions except in showers/storms that may cause
reductions to VSBYs at times.

Outlook...

Saturday...Mainly VFR, but a chance for mainly afternoon
and evening thunderstorms inland from the lakes.

Sunday...VFR/MVFR. Showers and thunderstorms likely.

Monday...Mainly VFR, but a chance for afternoon and evening
thunderstorms inland from the lakes.

Tuesday...Mainly VFR conditions expected.
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&&

.MARINE...
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A generally quiet period is expected for the lower Great Lakes
through the rest of the week and into the first half of the weekend
as a large upper-level ridge remains across the eastern CONUS,
resulting in a lighter surface flow. Only concern will be in the
afternoon and early evening hours as showers and thunderstorms could
produce briefly higher wind gusts and waves.

Increasing winds on Sunday will bring the next potential for Small
Craft Advisory conditions for both lakes.
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&&

.CLIMATE...
The heat will continue today. Below are record high
temperatures for our three main climate sites:

...Buffalo...

...Date.....Record Maximum (F)...Record warm Minimum (F)...

...June 20........92/1995............73/2012


...Rochester...

...Date.....Record Maximum (F)...Record warm Minimum (F)...

...June 20........95/1953............72/1923


...Watertown...

...Date.....Record Maximum (F)...Record warm Minimum (F)...

...June 20........90/1971............71/2012

Temperature records for Buffalo and Rochester date back to 1871.
Temperature records for Watertown date back to 1949.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Heat Advisory until 8 PM EDT this evening for NYZ001>008-
     010>014-019>021-085.
MARINE...None.

&&

$$

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