591
FXUS61 KBUF 151731
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
131 PM EDT Sat Jun 15 2024

.SYNOPSIS...
High pressure will build over the eastern Great Lakes tonight before
moving off the New England coast Sunday, bringing a continuation of
dry weather to the region. It will be cool tonight, then a warming
trend begins Sunday. Heat and humidity will build Monday, and last
through much of next week with high temperatures in the 90s and
dangerous heat index values peaking in the upper 90s to low 100s
Tuesday and Wednesday.

&&

.NEAR TERM /THROUGH SUNDAY/...
Visible satellite imagery showing diurnal cumulus fields early this
afternoon across higher terrain and along lake breeze boundaries.
These cumulus will tend to dissipate as the afternoon progresses and
the shallow layer of supporting low level moisture is depleted. High
temperatures will be a little below average for mid June, with upper
60s to lower 70s in most locales.

Tonight, surface high pressure will settle across the eastern Great
Lakes. Light winds, clear skies, and a cool/dry airmass will allow
for good radiational cooling. Lows will drop back into the 40s in
inland locations, with lower 50s along the immediate lakeshores.
Some of the coolest locations in the North Country may even drop
into the upper 30s.

Sunday, surface high pressure will drift east across New England,
then off the east coast by evening. Increasing warm advection in the
wake of the departing high will bring some periods of high cirrus,
but these should remain thin enough to still yield a mostly sunny
day. Temperatures will begin to move warmer, with highs in the low
to mid 80s for Western NY, and 70s for the North Country.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
...Dangerous Heat Wave Will Begin to Impact the Region...

Broad mid-level ridging centered across the Great Lakes Sunday will
continue its eastward progression into the eastern Great Lakes and
eventually center over the Northeast by Tuesday. Meanwhile within
the ridging, a shortwave trough will ride the top of the ridge
Sunday into Monday well to the north of the region. While this
shortwave trough indicates some active weather Sunday night, its
placement well to the north should keep most of the activity to the
north of the area though a few showers may be possible across the
North Country. Despite the ridge and surface high in place across
the Northeast, there is a slight chance for the potential for
diurnally driven convection.

Outside of this, deep southerly flow will advect in warmth and
moisture from the Gulf of Mexico initiating the heat wave for the
middle portion of the week. Of the first two days of the new work
week, Monday will be cooler. Though this being said, it will still
be quite sultry with highs in the upper 80s to low 90s across much
of the region and low to mid 90s across the climatologically warmer
spots of the Genesee Valley. Given not much respite in temperatures
Monday night (lows ranging in the upper 60s to low 70s),
temperatures Tuesday will soar into the 90s, with the typically hot
spots of the Genesee Valley approaching the 100 degree mark.

The hot high temperatures combined with the humidity will create
heat index values Monday to range in the upper 80s to mid 90s,
whereas Tuesday will see heat index values between 95 and 105
degrees. With such hot conditions, please remember to drink plenty
of fluids, stay in cooler areas (air conditioned or shaded), and
wear light loose clothing to help remain cool and avoid heat illness!

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
...Dangerous Heat Wave To Impact The Region Next Week...

A very strong 500mb ridge will anchor itself across much of the
eastern CONUS and western Atlantic through much of the week, which
will dominate the sensible weather across the eastern Great Lakes.
NAEFS ensemble guidance continues to indicate this ridge will be of
anomalous strength with 500mb heights and 850mb temperatures in the
99th percentile, if not exceeding the maximum climatological values
for the Northeast through Thursday. Deep anticyclonic flow around
the resultant Bermuda High will cause hot, humid air to surge across
the eastern CONUS. Given the strong signal from nearly all available
long range guidance packages, confidence is high in a prolonged
stretch of oppressive summer heat and humidity lasting through much
of the week.

Not much change to previous forecast packages with daytime highs
solidly in 90s Wednesday through Thursday. Highest temps will be in
the interior valleys, while cooler temps will be found immediately
along the lakeshores and immediately northeast of both lakes
(including Downtown Buffalo) as a persistent southwest flow advects
cooler marine air off the lakes. Have leaned more towards the ECMWF,
Canadian and ICON models for temperatures as the GEFS/GFS seems to
have too much convection/clouds given the strength of the 500 hPa
ridge.

Wednesday still seems like the peak day of excessive heat and
humidity with low 100s possible in interior valleys. This heat comes
as dewpoints climb into the low 70s, which will cause overall heat
indicies in the afternoon to climb into the mid 90s to lower 100s.

An upper level trough over south-central Canada will move east
through the end of the week. The approaching trough will begin to
suppress the strong ridge over the eastern Great Lakes region
Wednesday night. Based on the NAEFS, 850mb temperatures will begin
to fall into the upper teens Thursday through Friday, HOWEVER this
may only result in a few degrees difference from Tuesday and
Wednesday, continuing the heat wave across the forecast area. For
context, daytime highs average the upper 70s for Buffalo, Rochester,
and Watertown during the days of June 18-21. Record high
temperatures and record warm minimum temperatures are possible this
period, and the climate section below lists such records for
Buffalo, Rochester and Watertown.

Little relief is expected overnight with overnight lows in the upper
60s to mid 70s within a muggy airmass.

Otherwise...The primary forecast uncertainty through much of next
week continues to be the potential for convection. Daytime surface
based instability will greatly be present each afternoon with
dewpoints climbing into the upper 60s and low 70s although the
strong ridge should preclude much of the diurnal convective
potential with strong capping expected to be in place for Wednesday.
A shortwave driving through this ridge Thursday could bring an
isolated shower or thunderstorm Thursday or slightly better, on
Friday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
VFR will prevail through Sunday as high pressure drifts from the
eastern Great Lakes into New England. Diurnal cumulus this
afternoon, with bases in the 4-5k foot range, will dissipate by late
afternoon or early evening. A few periods of high/thin cirrus will
then cross the region tonight through Sunday. Winds will be
relatively light through the period.

Outlook...

Monday...VFR.
Tuesday through Thursday...VFR, but a slight chance for afternoon
thunderstorms inland from the lakes.

&&

.MARINE...
Winds and waves will remain below Small Craft Advisory criteria
through the rest of the weekend. North winds in the 10-12 knot range
will bring some light chop on Lake Ontario this afternoon. East
winds will increase Sunday, especially on the central and western
portions of Lake Ontario where it will become quite choppy.

Winds will then generally be light Monday through much of next week
as high pressure anchors over the Ohio Valley and New England.

&&

.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...None.
MARINE...None.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...EAJ
LONG TERM...HSK/PP/Thomas
AVIATION...Hitchcock
MARINE...Hitchcock
CLIMATE...Thomas