Heat Advisory 6, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
701 PM EDT Fri Aug 5 2022

.SYNOPSIS...
A dying cold front will slowly drift southward across the area
through this evening while generating some showers and
thunderstorms, some of which will produce heavy downpours before
diminishing after sunset. Sultry conditions will then persist right
through the weekend with some additional scattered showers and
thunderstorms possible each afternoon and evening, though much of
the time will be rain free. More numerous showers and thunderstorms
are then expected early next week as another cold front slowly
pushes across our region.

&&

.NEAR TERM /THROUGH SATURDAY/...
Regional radar imagery showing a classic weak flow convective
evolution this afternoon and evening, with highly variable storm
motion driven by outflow boundary interactions and lake breeze
boundaries. The most organized cluster of storms over the eastern
suburbs of Buffalo will continue for another hour or so before
quickly weakening. A few, more widely scattered showers and isolated
thunderstorms will also continue across the Southern Tier, western
Finger Lakes, and Genesee Valley for the next hour or two. Any
thunderstorm will produce local torrential downpours with localized
minor flooding possible. This risk will quickly diminish by sunset
as the storms use up available instability, and diurnal weakening of
instability accelerates with sunset.

Tonight whatever is left of the frontal boundary will completely
wash out across our region...with nocturnal stabilization and the
loss of low level forcing mechanisms bringing about a return to dry
conditions for the second half of the night. Dependent upon the
amount of cloud cover...continued very light winds and narrowing
dewpoint depressions may allow for the redevelopment of some patchy
fog within the Southern Tier valleys...and possibly also in any
areas that receive heavy rain this afternoon and evening. Otherwise
sultry conditions will continue...with overnight lows ranging from
the mid 60s across interior portions of the Southern Tier/North
Country to around 70 across the lake plains.

On Saturday our region will remain firmly embedded within a very
warm and sultry airmass...with highs ranging from the lower to mid
80s across the higher terrain to 85 to 90 across the lower
elevations...along with dewpoints averaging around 70 once again.
With synoptic forcing remaining very weak to nonexistent...we will
have to rely on the combination of diurnal heating and the
development of lake breeze/orographic circulations to trigger some
scattered afternoon convection...with the best coverage again mainly
found from the Southern Tier northeastward across the Finger Lakes
Region. While it is possible that a few spots across the Finger
Lakes could briefly reach low-end heat advisory criteria Saturday
afternoon...for now will hold off on any headlines given the
expected marginal nature of the conditions and the potential for
scattered afternoon convection.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Broad upper level troughing will be in place across eastern Canada
through the second half of the weekend. Southwest flow around the
Bermuda High will continue to feed moisture into the environment,
leaving our region with a warm and humid airmass with 850H temps in
the +17-18C range until late Monday night. Daytime highs Sunday will
range from the mid 80s across the higher terrain areas and northeast
of the lakes, to the upper 80s/low 90s elsewhere. Combined with
dewpoints in the low 70s, Heat Advisory criteria could be reached
for a period in the afternoon during peak heating, particularly east
of the Genesee Valley and across the Finger Lakes region. Nighttime
lows Saturday and Sunday nights will be rather muggy in the upper
60s to low 70s.

Otherwise, with a lack of synoptic forcing in place, precip chances
through Sunday night will generally follow a diurnal trend. This
means mainly dry weather Saturday night before pop-up showers/storms
re-develop Sunday afternoon, before coverage again tapers off
Sunday night. Though latest mid-range guidance seems to be
hinting at some (relatively) drier air being entrained aloft
Sunday, PWATs will still be elevated and with weak flow through
the upper levels, any showers that develop will be slow moving
and could bring locally heavy downpours.

The upper level pattern will begin to see a more significant shift
Sunday night into Monday, with a more pronounced upper level trough
and deepening surface low moving eastward across the Great Lakes.
The surface low is progged to track across Lake Ontario by Monday
evening, bringing a round of more widespread showers and
thunderstorms to the area Monday and Monday night. This system will
capture an impressive plume of deeper moisture with model guidance
indicating PWATs soaring well above 2", though stronger flow through
the upper levels should help keep storms moving a bit more than
those seen on Sunday. Confidence remains somewhat low on the details
as heavy rainfall potential and placement will largely depend on the
precise track of this surface low. Will leave out the mention of
heavy rain in the forecast for now until things come into better
focus.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The surface low will track east of the area by Tuesday morning, with
a trailing cold front bringing another round of wet weather to the
region during the day Tuesday. Shower/thunderstorm chances will
decrease from northwest to southeast Tuesday evening behind the
front. A secondary longwave trough will amplify as it slowly
pivots across the Great Lakes which may lead to a few pop-up
showers in the afternoon hours Wednesday. This feature will
ultimately bring another cold front to the region sometime
Thursday, though guidance continues to be split on the timing of
this feature. Will maintain slight chance PoPs for Thursday
afternoon for now.

Otherwise, a cooler and drier airmass working into the region will
bring temperatures and humidity back to much more comfortable levels
through the rest of the week. Temperatures will generally run near
or possibly a few degrees below normal for mid-August.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
A dying cold front will continue to push south across the area
through this evening, and this in tandem with lake breeze
boundaries and convective outflows will continue to produce a few
showers and thunderstorms. The most active area of convection near
KBUF will quickly weaken by around, or shortly after 00Z Sat.
Elsewhere, a few scattered showers and isolated thunderstorms will
continue through the early evening hours.

The showers and storms will taper off later this evening, with
general VFR conditions otherwise expected for overnight. This
said...some patchy IFR/MVFR fog will be possible within the Southern
Tier valleys later on tonight...as well as in any areas that receive
heavy rain this afternoon.

On Saturday...any patchy fog and attendant restrictions that do form
overnight will dissipate during the morning with renewed daytime
heating and mixing. The latter will also act in conjunction with
developing lake breeze and terrain circulations to lead to the
development of additional scattered afternoon convection across the
Southern Tier and Finger Lakes...with brief/localized IFR/MVFR again
possible within any storms. Outside of the above...general VFR
conditions will continue to prevail.

Outlook...
Saturday night through Tuesday...VFR/MVFR with a chance
of showers and thunderstorms...with the greatest chances for more
numerous to widespread activity and attendant restrictions Monday
night and Tuesday.
Wednesday...Mainly VFR.

&&

.MARINE...
With a general weak flow remaining in place across the Lower Great
Lakes...expect light to modest winds and minimal waves to continue
through the weekend. While a few isolated showers and storms cannot be
ruled out each afternoon and evening...in general mainly dry
conditions should prevail across the Lower Lakes until another
frontal boundary approaches the region Sunday night and Monday.

&&

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

&&

SYNOPSIS...Hitchcock/JJR
NEAR TERM...Hitchcock/JJR
SHORT TERM...PP
LONG TERM...PP
AVIATION...Hitchcock/JJR
MARINE...Hitchcock/JJR

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