092
FXUS61 KBUF 181809
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
209 PM EDT Tue Jun 18 2024

.SYNOPSIS...
Hot and humid weather through at least Thursday with apparent
temperatures likely to reach 100F at many locations during the
afternoon hours today through Thursday. There will also be
showers and thunderstorms at times, especially during the
afternoon and early evening hours.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Remnant clouds from convection earlier today will move across
the Eastern Lake Ontario region. This will slow rises in
temperatures some there, as it did for areas to the west when it
moved through. Since showers and storms moved through,
temperatures haven risen steadily in Western NY, with highs on
track to reach the upper 80s to lower 90s today. Heat index
values are still on track to reach into the mid 90s to lower
100s this afternoon, making very dangerously hot and humid
conditions. Heat advisories remain in place for the entire
forecast area.

The departing wave also impacted convection today, with the
slightly slower warming leading to a later onset of instability
convection this afternoon. Still impressive CAPE values over
2000 J/Kg early this afternoon, with the most unstable
conditions across the Western Southern Tier which was not
impacted the convective wave this morning. Radar trends show
thunderstorms developing to our south and west, and expanding cumulus
fields suggest its only a matter of time before storms develop
there mid to late afternoon. Noted the HRRR is too low in its
dew points, which is likely causing it to be too slow with is
convective initiation. Overall there is low forecast confidence
in exact timing and location of storm development.

The 12Z Buffalo sounding showed precipitable water values of
1.77 inches, and any storms that develop today will have the
potential to produce torrential downpours. Also, winds aloft are
weak, with upstream radar trends showing a potential for
backbuilding. As a result there is a marginal risk for flash
flooding, mainly across the Western Southern Tier and Upper
Genesee Valley even if overall coverage is scattered. The
severe weather risk appears limited due to the weak wind
profiles and the departure of the convective shortwave. However,
the severe weather risk is non- zero since disorganized pulse
convection can still produce damaging winds.

Any afternoon and evening convection will diminish overnight
tonight, other than perhaps a stray shower or storm. There will
be little reprieve from the muggy conditions with low
temperatures in the lower to mid 70s, with some upper 60s across
the Southern tier and North Country.

Wednesday will likely be the hottest day of this heat wave for
most areas. 850mb temperatures will continue to hover around
+20C, supporting another day with highs in the upper 80s to mid
90s. In addition, dew points will be slightly higher in the
lower 70s at most locations, leading to heat index values to top
out in the lower 100s at many locations. The lower Genesee
Valley and city of Rochester will be close to heat warning
criteria (105).

The region will remain within an upper level ridge, with a weak
flow aloft. Instability thunderstorms are possible during the
afternoon hours, especially along and inland of lake breezes.
PWAT values will remain high, with slow storm motion again
presenting a risk for localized flash flooding where storms
develop.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
...Heat Advisory in Effect for the Entire Area as Dangerous Heat
Builds Through Thursday...

Hot and humid daytime conditions and warm and muggy nights will
persist through at least Thursday as a result of surface high
pressure remaining anchored along the Eastern Seaboard in
conjunction with a slowly amplifying upper level ridge across
the eastern CONUS. Nighttime conditions will continue to feel
muggy despite a drop in the heat index values.

Thursday, the ridge will drop south and southeast. This slight jog
from it`s position Wednesday will allow for a slight drop in
temperatures and heat index values Thursday. Despite the slight drop
in conditions, Thursday will continue to be hot and humid, with heat
index values ranging in the mid 90s to low 100s for the bulk of
western and north central New York.

The positioning and proximity of the upper level ridge will
suppress most of the convection, however afternoon heating and
instability with some forcing along the lake breeze boundaries
may support some showers and thunderstorms. A better chance for
an isolated showers and/or thunderstorm will lie across the
North Country/Saint Lawrence Valley closer to the northern
periphery of the ridge.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Heading into the end of the week and into the start of the new work
week, expect a gradual day-to-day cooling trend due to multiple
successive shortwave troughs traverse eastward across central and
eastern Canada, acting to slowly suppress the ridge southward. As a
result this will create quasi-zonal flow across the CONUS by Monday.
Even with the "cooling" trend, conditions will continue to remain on
the warm and humid throughout the end of the week and into the
weekend. Temperatures Friday will feature upper 80s to low 90s
before cooling off to the mid to upper 80s by Sunday. As mentioned
previously with the humidity, heat index values will range between
the low to mid 90s Friday and then in the mid to near 90 by Sunday.

With regards to precipitation, there will be a slight increase in
the potential for convection Friday through Sunday due to upper
level disturbances riding the northern periphery of the upper level
ridge and a surface boundary sagging south into the region from
Canada. Areas that do receive storm activity will have a slight
reprieve from the warm muggy conditions, through it will be on the
shorter side.

Sunday night into Monday, a deep trough and associated surface low
and cold front will track east across the region, resulting in
widespread showers to pass across the region. With this system, air
conditions will be notably cooler in the wake of the front. Highs
Monday will return to near normal with highs in the upper 70s to mid
80s region wide.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Mainly VFR flight conditions for the 18Z TAF cycle. Scattered
thunderstorms will develop this afternoon, and these may briefly
result in heavy rain and IFR or lower conditions at times.
Greatest risk for this is at KJHW. Storms will weaken and
decrease in coverage tonight.

Chances for thunderstorms increase again Wednesday afternoon due
to daytime instability. Without a large scale trigger for the
convection, it should be scattered with best chances in the
Western Southern Tier and Upper Genesee Valley.

Outlook...

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

Sunday...VFR/MVFR. A chance of thunderstorms.

&&

.MARINE...
High pressure will be near the eastern Great Lakes through much of
this week, offering light winds, generally 15 knots or less on the
lakes. Locally higher winds and waves are possible in scattered
periodic thunderstorms.

&&

.CLIMATE...
A prolonged period of heat is expected for our region this week.
Below are record high temperatures for our three main climate
sites:

...Buffalo...

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

...June 18........95/1994............73/2006
...June 19........90/2001............73/1919
...June 20........92/1995............73/2012


...Rochester...

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

...June 18........97/1957............72/2018
...June 19........95/2001............72/1919
...June 20........95/1953............72/1923


...Watertown...

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

...June 18........91/1957............70/1992
...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
NEAR TERM...Apffel
SHORT TERM...EAJ
LONG TERM...EAJ
AVIATION...Apffel
MARINE...Apffel/TMA
CLIMATE...Thomas/TMA