275
FXUS61 KBUF 190815
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
415 AM EDT Fri Jul 19 2024

.SYNOPSIS...
Sprawling high pressure over the Great Lakes will remain over
the region through Saturday. This will provide fair weather and
comfortable conditions through at least the first half of the
weekend, then a weak moisture starved cold front will fall apart
over our region on Sunday. Our next chance for widespread
shower activity will come Tuesday and Wednesday of next week
when mid summer humidity will return.

&&

.NEAR TERM /THROUGH SATURDAY/...
High pressure will continue to build across the region today.
Forecast soundings are notably drier in the low levels than
yesterday, so expect a muted diurnal cumulus response in comparison,
yielding mostly sunny skies. Temperatures today should fall short of
normal with highs in the mid to upper 70s.

Mainly clear skies and light winds tonight will lead to ideal
radiational cooling conditions, allowing temperatures to fall
into the 50s along with some patchy Southern Tier valley fog.

Troughing occurs across the Great Lakes Saturday. A southwest flow
in the mid-levels will bring increasing moisture and warm air across
the region. Dry conditions are expected with temperatures building
back into the 80s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Fair weather Saturday with surface high pressure sliding eastward.
Still under cyclonic flow aloft, which will hold temperatures to
near normal levels, with afternoon cumulus. Farther to the south a
southerly flow of Atlantic moisture may spill a thicker cloud cover
into southeastern Allegany County.

Quiet weather Saturday night through Sunday, though we will watch a
weak cool front drop southward into our region. Along this front,
clouds will gather within a ribbon of deeper 850-700 hPa moisture,
with just a slight chance for a shower or thunderstorm east of Lake
Ontario late Saturday night and Sunday.

This front will stall across the Southern Tier Monday, and though
moisture is lacking, a shower or thunderstorm may develop along the
boundary during the afternoon.

Temperatures will be near to slightly above normal with the base of
a longwave trough over our region.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
The longwave pattern across the CONUS will gradually shift moving
further into the new workweek. This will come as a deep closed low
slinks out of the Gulf of Alaska and towards the Pacific Northwest,
causing a deeper amplification of the ridging over the Desert
Southwest while downstream troughing remains over the Mississippi
Valley. Reinforcing shortwave energy will concurrently propagate
southeast out of central Canada and into the Great Lakes region,
resulting in a broad, positively tilted trough replacing the zonal
flow over much of the eastern half of the the Lower 48. This trough
will allow a gradual northward advection of GOMEX based moisture
into the Northeast.

In terms of how this will impact the sensible weather across the
eastern Great Lakes, the increasingly unstable environment will
allow for a return to a much more unsettled pattern with chances for
showers and thunderstorms Tuesday through Thursday. In general,
chances will be highest across the interior in the afternoon hours
each day when diurnal heating is at its strongest, while diminishing
overnight and into the morning hours. PWATs near or exceeding 1.7"
within this increasingly humid airmass will allow for periods of
heavy rain, though there remains typical long range model
discrepancies on how exactly the trough across the East will evolve
which limits certainty in timing, placement and amounts.

Temperatures Tuesday will top out in the low to mid 80s in most
spots, while reaching the upper 70s and low 80s Wednesday and
Thursday though with increased humidity. Overnight lows with range
in the 60s each night.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Southern Tier Valley fog could impact KJHW through 11z, otherwise
SKC early this morning. Surface high pressure will continue to build
across the region today. There will be limited flux off Lake Erie
and Lake Ontario, therefore the expectation is for some sct-bkn
higher based diurnal cumulus during peak heating this afternoon.

Outlook...

Tonight through Monday...VFR. Patchy early morning valley fog.
Tuesday...Showers and thunderstorms possible. Mainly VFR/MVFR.

&&

.MARINE...
High pressure over the Upper Mississippi valley will slowly settle
across all of the Great Lakes region through the weekend. This will
result in a weak pressure gradient only supporting gentle to
occasionally moderate breezes and negligible waves through the
weekend.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...RSH/TMA
NEAR TERM...TMA
SHORT TERM...Thomas
LONG TERM...PP
AVIATION...TMA
MARINE...RSH/TMA