338
FXUS61 KBUF 181345
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
945 AM EDT Tue Jun 18 2024

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

&&

.NEAR TERM /THROUGH TONIGHT/...
The first issue to contend with is an area of convection across
the Niagara County frontier which is not well captured by model
guidance. There`s still ample instability in place to support a
cluster of thunderstorms, and the 12Z Buffalo sounding shows
a PWAT of 1.77 inches. As a result, this slow moving cluster of
storms is producing very heavy rainfall which has prompted a
flash flood warning for Niagara County this morning. The 12Z
Buffalo sounding doesn`t show as much wind shear as there was
yesterday, so the potential for severe weather with this is
lowered, but still non-zero since pulse convection can still
produce damaging winds.

Little overall change to the airmass over the lower Great Lakes
today. Mid level ridge will continue to amplify today with 850
mb temperatures around +20C. Only a few spots managed to get
into the lower 90s on Monday, but should see more widespread 90s
today given the rising heights aloft. It will also be more
humid with dewpoints rising to into the lower 70s. This
combination will result in dangerously hot conditions with heat
index values in the upper 90s to lower 100s. It may be locally
cooler where storms develop. Heat Advisory remains in effect
for the entire area.

Outside of the early morning convection working through the
eastern Lake Ontario region, and perhaps a stray shower or storm
elsewhere the bulk of the expected convection will hold off
until this afternoon and evening. With the area still on the
periphery of the building ridge, a disturbance riding along the
ridge will work into the region late in the day. This
disturbance along with any lake breeze boundaries will trigger
scattered showers and storms. Strong surface heating will
contribute to destabilization underneath the building ridge.
Most mesoscale guidance suggests the best chances will be across
the Southern Tier into the Finger Lakes, although convection
could occur just about anywhere just inland from the lakeshores.
Some of the cells will be capable of producing very heavy rain
and strong gusty winds, with the lastest SPC Day One outlook
highlighting the entire area in a marginal severe thunderstorm
risk.

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.

&&

.SHORT TERM /WEDNESDAY 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 throughout the middle of the week 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

Heading into Wednesday, the mid-level ridge will remain strongly in
place across the region, with some ensemble models depicting heights
closing in on 600 dm. This being said, temperatures at 850s mb will
remain around +20 Celsius and therefore support high temperatures in
the mid to low 90s. As mentioned previously, the humidity will
create sultry conditions with apparent temperatures ranging in the
90s during peak heading hours (mid-day through the afternoon).
Similarly, 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.

For both days, 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 MONDAY/...
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 /14Z TUESDAY THROUGH SATURDAY/...
Mainly VFR flight conditions through the day today, outside of
localized thunderstorms which will produce heavy rain and IFR
or lower at times. These will be very difficult to predict much
in advance since convection is being driven by very subtle
features. In general, expect coverage to increase this afternoon
and evening, then to diminish tonight.

Outlook...

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

&&

.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.

&&

.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 NYZ001-002-006>008-
     010>012-019>021-085.
     Heat Advisory until 8 PM EDT Thursday for NYZ003>005-013-014.
MARINE...None.

&&

$$

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