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236
FXUS61 KBUF 200017
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
817 PM EDT Wed Jun 19 2024

.SYNOPSIS...
Hot and humid weather will linger through at least Thursday with
apparent temperatures likely to reach 100F at many locations during
the afternoon hours. There will also be showers and thunderstorms at
times, especially during the afternoon and early evening hours.
While temperatures will remain well above normal, a modest respite
from the heat will come in time for the weekend, as a cold front
will approach the region on Friday,

&&

.NEAR TERM /THROUGH TODAY/...
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Hot and humid weather will continue, with a Heat Advisory still
in effect for the entire area through Thursday. An upper level
high across the Mid-Atlantic will move very slowly southward
Thursday and Thursday night.

In regards to possible convection...our airmass is nearly identical
to that from late yesterday (Tues) when strong to severe
thunderstorm activity blossomed over the western Southern Tier...
Genesee valley and Finger Lakes region. It goes without saying that
this sub tropical airmass is quite unstable...but shear is limited
at best. Tds in the low to mid 70s and PWAT values avg 1.8" continue
to favor convection with torrential downpours...but unlike Tuesday
when a light flow and short MBE vectors elevated the risk for slow
moving storms...the flow is just a skosh stronger., This can be
attributed to the mid level ridge becoming oriented southwest to
northeast with its axis sagging to the southeast of our forecast
area.

Now that you know the environment...we need to have a trigger to
touch off the convection. The lake breeze boundary that drifted east
from the lake late this afternoon has since stalled and has
generated nothing but some enhanced Cu. There is some kind of
boundary though that stretches from the heart of the Finger Lakes
southwestward across Allegany county to northwestern Pennsylvania
though. This boundary is slowly pushing west-northwest. Convection
along this boundary has tried to get going the past couple hours...
but the cellular activity has been short lived with nothing to show
for it but localized quarter inch rainfall and some lightning. Some
of the CAMs are still suggesting that storms will become more
widespread along this boundary as we push through the late evening
hours. I am skeptical of this with the setting sun and instability
waning somewhat...but will continue vigilant surveillance.

Otherwise...any storms that do develop should weaken/taper off LATE
this evening. However, there will remain a small risk for showers or
thunderstorms if any upstream convective waves move through since it
will still be instability overnight. Lows will range from the upper
60s to lower 70s, with patchy fog in the Southern Tier river valleys.

Heat index values on Thursday may be slightly lower since 850mb
temps will drop to +18C, but values will still be within
advisory criteria, reaching 100 again at some locations. High
temperatures will be 2-3 degrees lower than today at most
locations.

The southward progression of the upper level ridge should allow
for earlier and more widespread convective initiation on
Thursday. This is reflected in model guidance also, with storms
developing along and inland of lake breeze boundaries early
afternoon. There will again be a risk for slow moving storms and
flash flooding. Winds aloft and shear will be slightly more, so
there will again be a risk for severe weather with damaging
winds and hail possible. SPC has most of the area in a marginal
risk for severe weather, with greater slight risk near Central
NY. Showers and storms will gradually diminish late Thursday
night. A partial clearing may allow for areas of fog to develop
Thursday night, especially in the Southern Tier.
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&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Friday, the frontal boundary stalls over the forecast area and will
continue to provide the opportunity for showers and thunderstorms
with the best chance for showers toward the NY/PA line. High
temperatures on Friday will be in the low 80s to near 90, on the
northern side of the frontal boundary. If the front stalls farther
north, then temperatures will be a bit warmer.

Warmer and more humid conditions return for the weekend as warm
front moves north of the forecast area.

Friday night, the front stalled over the area will start to slowly
push north as a warm front late in the night and into the early
morning on Saturday. There should be a break in the shower/storm
activity, especially with the lack of diurnal processes.
Showers/storms potential will increase around/after daybreak
Saturday morning as the front starts moving north and a ribbon of
vorticity and area of increased moisture pushes toward and across
the region. As of now, the best chance for showers early Saturday
morning looks like it should be over the North Country. Certainly
can`t rule out a shower or storm for the rest of the area as the
warmth and humidity build back into the region.

Showers will expand in coverage across the entire area through the
day on Saturday as daytime heating increases, and as the sfc low
(and its moisture) well to the north approaches the region. With the
frontal boundary generally from west to east just to the north of
Lake Ontario and into the North Country, the best chances for
showers and storms will be located along the front. Afternoon high
temperatures will warm to the low 80s to low 90s across the area,
with the cooler temperatures expected across the North Country with
the warm front over/near the area.

The warm sector of the surface low to the north will be firmly in
place for Saturday night continuing the potential for showers/storms
across the entire area.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
With the warm sector of the surface low to the north still in place
for Sunday, showers/storms will continue across the entire area.
Showers will increase from northwest to southeast across the area
into the afternoon as a cold front approaches from the west.
Warm and humid conditions will continue through Sunday as the warm
sector remains in place ahead of the cold front.

The cold front associated with the surface low passing to the north
will cross the area on Sunday evening and into the night, causing
more organized showers/storms to move through the area. A potent
shortwave trough tracking across the area behind the passing front
will continue the shower potential for Monday.

Increased ridging and an incoming surface high will result in drier
conditions for Monday night through most of the rest of the period,
though some guidance does bring some showers back into the region
for mid-week.

Temperatures will be well above normal for Sunday with highs in the
low 80s to near 90. Temperatures cool behind the passing cold front
to the mid 70s to low 80s for Monday before warming again for
Tuesday & Wednesday back to the low to upper 80s.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Mainly VFR flight conditions through this evening. Showers and
storms before 03z (11 PM) will produce localized MVFR or lower
conditions at times. Storms will mainly develop along and inland
of lake breeze circulations, with a lower risk at KBUF/KIAG/KART
than at KROC and KART.

Mainly VFR late tonight, but there is a risk of fog in the
Southern Tier river valleys.

On Thursday, mainly VFR again outside of showers and
thunderstorms. These will develop early afternoon and last
through the evening hours. Areal coverage a bit more than today,
with a risk of heavy rain and gusty winds.

Outlook...

Thursday night...VFR except areas of IFR or lower in areas of
fog. Also a chance of thunderstorms.
Friday and 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.

&&

.MARINE...
A generally quiet period is expected for the lower Great Lakes
through the rest of the week and into 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 this week as daily isolated to
scattered thunderstorms could produce higher wind gusts and
waves.

&&

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

...Buffalo...

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

...June 19........90/2001............73/1919
...June 20........92/1995............73/2012


...Rochester...

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

...June 19........95/2001............72/1919
...June 20........95/1953............72/1923


...Watertown...

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

...June 19........91/2007............70/1949
...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 Thursday for NYZ001>008-010>014-
     019>021-085.
MARINE...None.

&&

$$

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