933
FXUS61 KBUF 140252
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1052 PM EDT Tue Aug 13 2024

.SYNOPSIS...
Expansive high pressure centered over the Mississippi Valley will
build east and support mainly dry weather through mid week, although
there could be a few hit and miss showers. Better chances for
showers and thunderstorms will arrive late Friday and into the
weekend. Temperatures will become gradually warmer as the week
goes on.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
A swath of wildfire smoke over the western counties will continue to
drift south during the overnight...while mainly clear skies will be
found elsewhere. The mainly clear skies and light winds from high
pressure sitting over us will lead to another decent night of
radiational cooling...so temps by daybreak will range from the upper
40s in the coolest southern tier valleys to near 60 along the shores
of Lakes Erie and Ontario.

There will be quite a bit of sunshine again on Wednesday with warmer
weather and high temperatures in the upper 70s to lower 80s. An
isolated shower is again possible, across the Southern Tier and also
the North Country.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
A broad surface ridge will begin this period to our west, with light
northwest flow continuing low humidity and pleasant overnight
temperatures in the lower 50s inland to lower 60s closer to the
warmer lake shoreline. Any spotty evening showers east of Lake
Ontario Wednesday evening will quickly diminish with the
stabilization of the lower atmosphere.

This surface high will cross our region Thursday, yet aloft a
departing mid level trough will linger enough moisture to allow for
a spotty shower or thunderstorm through the afternoon hours. This
activity will wane in the evening.

A light southeast flow will develop Thursday night, and along with
increasing mid and high level clouds from the west will lead to
slightly warmer air temperatures overnight. Most areas will have
overnight lows in the lower to mid 60s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The ridge of high pressure will move east of the Great Lakes to New
England Friday. In its wake, a longwave trough will then slowly
encroach on the forecast area from the west as it digs down to the
Southeast states from Ontario and Quebec. A sharpening, cyclonically
curved jet rounding the base of this trough will allow for a steady
transport of GOMEX moisture into the eastern Great Lakes region with
increased humidity and PWATs quickly rising to between 1.5-1.9" from
west to east Friday. Combined with the increased synoptic forcing
and large scale height falls aloft, expect chances for showers and
thunderstorms to increase in tandem Friday, with precipitation
`likely` in the western Southern Tier by the afternoon. A period of
steadier rain, which could be heavy at times, is then expected
across WNY on the nose of the stronger jet energy Friday night
though a slot of relatively drier air on its heels may cause precip
to be more of the showery variety later in the night.

Very unsettled weather persists across the entire forecast area
through the weekend and possibly into Monday as the mid-level trough
partially closes off north of the region, causing its eastward
progression to dramatically slow. Deep layer RH fields and model QPF
depicted by the long range guidance suggests that there should be
some dry time in the mix, though timing of these breaks becomes
difficult to pin down with typical model discrepancies in timing and
placement. With this in mind have undercut NBM PoPs a small amount,
staying below `categorical` range until these details come into
better focus. In general, expect the greatest chances for showers
and thunderstorms Saturday through Monday to be during peak diurnal
heating hours in the afternoon each day, though this activity could
persist through the overnight periods with the main 700-500mb trough
axis still upstream until sometime Monday evening. Given the high
PWATs in place, some of this convection could result in locally
heavy rainfall, especially Saturday and Sunday.

Once the trough axis finally shifts eastward, surface high pressure
will begin to slowly build back into the region from the Ohio Valley
Monday night into Tuesday. There could be enough wrap-around
moisture present to spur the development of a few additional
showers, though the overall pattern favors lower chances for precip
during this period.

Temperatures will be warmest Friday with highs in the upper 70s/low
80s as warm advection should be ongoing out ahead of the large
system to the west. Slightly cooler air within the trough should
lead to a slight cooling trend through Sunday, with near normal
temperatures then expected into early next week.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
While VFR conditions with light winds will remain in place through
Wednesday...there will be patchy fog between 07 and 12z that will
result in MVFR to IFR conditions at sites such as KJHW and KELZ.

Outlook...

Thursday...Morning fog across the western Southern Tier
otherwise VFR.
Friday...Mainly VFR. Chance for showers late.
Saturday and Sunday...Areas of IFR or lower with showers and
thunderstorms likely.

&&

.MARINE...
High pressure across the eastern Great Lakes will maintain quiet
conditions on Lake Erie and Lake Ontario through mid week. The light
flow will favor the development of afternoon lake breezes through
Thursday. A southeasterly flow will develop by Thursday night and
Friday as a warm front approaches the region, but speeds should
remain less than 15 knots. A general south-southwest flow develops
behind the warm frontal passage for the weekend period as low
pressure meanders north of the lower Great Lakes.

Speeds could exceed 15 knots both Saturday and Sunday afternoons,
so cannot completely rule out the potential for marine headlines
this weekend. The risk for thunderstorms increases on the Lower
Great Lakes Friday through Sunday.

&&

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

&&

$$

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