-- Discussion containing changed information from previous version are highlighted. --
424
FXUS61 KBUF 172021
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
421 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/...
Remnant MCV working through the CWA with showers and thunderstorms
popping across the S.Tier and western Finger Lake region. Some of
these cells will be capable of producing brief heavy rain and strong
gusty winds late this afternoon into this evening. For this
reason...SPC has a vast majority of our CWA in a MRGL risk.

Otherwise...sultry conditions will continue with dewpoints in the
60s and temps solidly in the 80s to low 90s in spots. Given the
above conditions...apparent temperatures will be found in the mid to
upper 90s in the lower Genesee Valley and Western Finger lakes where
a Heat Advisory is in place.

Tonight...little reprieve from the muggy conditions and lows will be
found in the upper 60s to lower 70s. We still can`t rule out a few
showers within this muggy conditions and unstable atmosphere. There
also could be some fog in the Southern Tier river valleys tonight,
especially at locations which receive rain.

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 THURSDAY NIGHT/...
-- Changed Discussion --
...Heat Advisory in effect for the entire area as dangerous heat
builds through Thursday...

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 approaching 600 dm. 850 mb temperatures stay around
+20C. Most high temperatures again in the upper 80s to 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.

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 Wednesday, 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 of
convection, but afternoon heating and instability with some forcing
along lake breeze boundaries may bring some showers and storms each
afternoon. Better chance for an isolated shower/storm would be
toward the North Country/Saint Lawrence Valley closer to the
northern periphery of the ridge.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
-- Changed Discussion --
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.

A deep trough, sfc low and cold front will track across the region
on Sunday night into Monday morning with widespread showers
possible. The most notable change with this system will be the
cooler air moving in behind the front. Highs on Monday will drop
back into the upper 70s to mid 80s for the entire area.
-- End Changed Discussion --

&&

.AVIATION /20Z 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...AR
SHORT TERM...JM/TMA
LONG TERM...JM/SW
AVIATION...Apffel
MARINE...Apffel/Thomas
CLIMATE...Thomas