878
FXUS61 KBUF 171850
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
250 PM EDT Mon Jun 17 2024

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

&&

.NEAR TERM /THROUGH TUESDAY/...
A convectively induced shortwave across southern Ontario
province and eastern Lake Erie will move across the area
through this evening. Showers and thunderstorms generated by
this have been somewhat suppressed by the lake breeze on Lake
Erie, but as this shortwave and moisture moves across the
greater instability which is in place east of the lake breeze
expect the showers and storms to increase in areal coverage.
This is fairly well captured by mesoscale guidance, with showers
and thunderstorms expected to expand across the Western
Southern Tier, upper Genesee River valley, and Western Finger
Lakes regions. Some storms may also develop in Niagara County
along the northern fringe of the lake breeze. Fairly weak flow
aloft will result in slow moving storms, with a potenial for
locally heavy downpours. MCV will somewhat enhance the limited
wind shear in place with a low, but non-zero risk for severe
thunderstorms with gusty winds the primary risk. Given these
factors SPC has introduced a marginal risk for severe weather
for today.

Otherwise, this afternoon will be hot and humid. Highs will
generally range from the upper 80s to lower 90s. Apparent
temperatures will rise into the mid to upper 90s in the lower
Genesee Valley and Western Finger lakes where a Heat Advisory is
in place. A few spots will be slightly cooler where showers and
storms develop.

Tonight will be warm and muggy with lows in the upper 60s to
lower 70s. Can`t rule out a few showers within this muggy and
still unstable atmosphere. There also could be some fog in the
Southern Tier river valleys tonight, especially at locations
which get rain today.

Slightly warmer aloft on Tuesday with 850mb temperatures rising
to about +20C. It will also be more humid with dew points rising
to around 70. This combination will result in dangerously hot
conditions outside with heat index values in the upper 90s to
lower 100s. Forecast highs trended slightly down due to the
increased confidence in daytime instability showers and
thunderstorms which will result in modest/localized relief from
the heat. However, with this, dew points and moisture are
slightly higher so heat index values still support a Heat
Advisory for the entire forecast area.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
...Heat Advisory in effect for the entire area as dangerous heat
builds through mid week...

Surface high pressure will remained anchored along the eastern
seaboard as a slow amplification of the eastern CONUS ridge
takes place during the period. This will result in a deep southerly
flow which will bring HOT and HUMID conditions during the day and
WARM and MUGGY conditions at night.

Mid level ridge will be firmly in place Wednesday with
ensembles showing heights around approaching 600 dm. 850 mb
temperatures stay around +20C. Most high temperatures again in
the lower 90s across the region with valley locations reaching
the mid to upper 90s, with apparent temperatures in the upper
90s to lower 100s from midday through the afternoon. Nighttime
temperatures will also remain elevated, with muggy conditions
lasting even if heat index values drop some after sunset.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
...Dangerous Heat Wave Will Continue For The Region Through At
Least Thursday...

Model consensus shows the axis of the anomalously strong nearly 600
decameter ridge will be just to our south and southeast Thursday,
just a slight jog from its position on Wednesday. This may bring 500
mb heights down just a smidge, along with surface temperatures/dew
points possibly a couple of degrees cooler. All in all, very similar
to the hot and steamy conditions expected for Tuesday/Wednesday,
which will make Thursday the most oppressive day of the long term
period with heat index values again ranging from the mid 90s to very
low 100s for the bulk of western and northcentral NY.

Positioning/proximity of the upper level ridge will suppress most,
if not all convection, especially across western NY. Better chance
for an isolated shower/storm would be toward the North Country/Saint
Lawrence Valley closer to the northern periphery of the ridge.

A very gradual day-to-day `cooling` is then expected for the Fri-Sun
timeframe as successive shortwaves traversing eastward through
central and eastern Canada slowly suppress the ridge to the south,
leaving a quasi-zonal flow in place across the CONUS by the end of
the period. That said, still want to emphasize that conditions are
still going to remain very warm to hot with elevated humidity
levels. In terms of temperatures, upper 80s/low 90s Friday will
slowly trend downward to the mid and upper 80s by the end of the
weekend, with the highest elevations several degrees cooler
respectively on any given day. Heat index values will reach the low
to mid 90s for all of the lower terrain Friday afternoon, upper 80s
to low 90s Saturday afternoon, and mid 80s to near 90 by Sunday.

In terms of precipitation, there will be some increase in convection
potential as we close out the work week and head into next weekend.
This will be owed to mainly two things: Upper level
disturbances riding the northern periphery of the upper ridge
passing closer and closer to the area as the center of the ridge
slowly sags further south through the period, while a surface
boundary also sags south toward the region from Canada. Areas
that do receive some showers/storms, will enjoy some relief,
however any reprieve will only be temporary.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
For the 18Z TAFS, there will be mainly VFR flight conditions.
However, a few showers and thunderstorms cannot be ruled out
across Western NY this afternoon which may briefly produce MVFR
or lower flight conditions. Any impacts will be brief.

Fog is possible in the Southern Tier river valleys. Confidence
is too low to include in the KJHW TAF but there a risk it will
develop there.

Otherwise, mainly VFR flight conditions on Tuesday morning then
more showers and storms will develop during the afternoon hours.
Localized MVFR or lower possible.

Outlook...

Tuesday 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, starting
Monday June 17th. Below are record high temperatures for our three
main climate sites:

...Buffalo...

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

...June 17........94/1994............73/2006
...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 17........94/1994............70/1994
...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 17........89/1994............68/1949
...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 from noon Tuesday to 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
NEAR TERM...Apffel
SHORT TERM...TMA
LONG TERM...JM
AVIATION...Apffel
MARINE...Apffel/Thomas
CLIMATE...Thomas