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000
FXUS61 KBUF 181900
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
300 PM EDT Fri Jun 18 2021

.SYNOPSIS...
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While our more humid airmass will support scattered showers and even
a few thunderstorms early tonight and again on Saturday...the bulk
of the time will be rainfree. Sunday should prove to be the nicer of
the two days with only a minimal chance for afternoon showers across
the SOuthern Tier.
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&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
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While most of the area will be rainfree this evening...a few showers
and thunderstorms will re-develop ahead of a warm front. This will
especially be the case across the Southern Tier...where it is still
not out of the question that a strong thunderstorm could form
between 23 and 03z. Scattered showers will then taper off in
coverage during the overnight.

After a dry start on Saturday...a few showers and thunderstorms
could develop during the midday and afternoon in advance of an
approaching shortwave. Again...the bulk of any activity should be
focused on the Southern Tier.

Weak low level ridging and nocturnal stability will kill off any
convection early Saturday evening...leaving the rest of the night
pcpn free.
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&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Low amplitude ridging works overhead Sunday, allowing for mostly dry
conditions. Deterministic guidance has been indicating a very weak
upper level shortwave crossing the area in the afternoon, which
combined with diurnal instability could kick up a few
showers/thunderstorms. For now, added low chance PoPs for Sunday
afternoon mainly from the Southern Tier east to the Finger Lakes
region, which looks to be in closer proximity to the passing
shortwave. Though the first half of Sunday night will likely remain
dry, rain chances will gradually increase from west to east moving
closer to Monday morning ahead of an approaching upper-level
longwave trough. A warm front moving in from the south the area will
help moderate overnight temperatures, with lows only dipping into
the upper 60s and low 70s, lower 60s across the western Adirondacks.

The aforementioned large upper level trough will dig across the
upper Midwest/upper Great Lakes on Monday while the strengthening
main surface low pressure pivots northeast just south of James Bay.
A strong trailing cold front will approach from the west on Monday,
providing the larger scale forcing and bringing widespread shower
and thunderstorm chances to the area. Though model guidance
continues to keep any remnants of the tropical system currently
moving towards the Gulf Coast away from the Great Lakes region,
strengthening SW flow out ahead of the front will still allow GOMEX
moisture to surge northeast across the area. This, combined with a
50kt+ 850mb jet passing overhead and surface trough axis swinging
through the area, should lead to the likelihood for showers and
thunderstorms to break out across the area by Monday afternoon, some
of which could be on the stronger side. PWATS nearing 2" will bring
the potential for locally heavy rainfall.

At the same time, a strengthening upper level jet over the upper
Great Lakes will aid in the development of low pressure on the cold
front under the right entrance region of the jet, acting to slow the
eastward progression of the surface boundary. This will allow
showers and storms to linger into Monday night, though decreasing
amounts of instability should help limit overnight thunderstorm
coverage. The cold front will slowly cross the area sometime closer
to Tuesday morning, as surface low pressure rides northeast along
the boundary.
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&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
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Plentiful moisture will still be in place and right entrance region
of the upper jet overhead, continuing to support the likelihood of
showers right into the day on Tuesday, with lessening chances for
thunder as the day progresses owed to instability getting shoved
east of the area with the boundary.

Main upper trough axis crosses the area Tuesday night with the
chance for a few lingering showers. A much cooler and drier airmass
is then set to move into our area for Wednesday and Thursday as high
pressure builds across the area from the west. Upper troughing will
remain overhead which will keep the cooler air locked in over the
Northeast and Mid Atlantic. Despite any diurnal instability that
develops with the cool airmass overhead, limited moisture will
preclude much in the way of any shower development either day, with
much of the time remaining dry.

Otherwise, above normal temperatures and high humidity levels on
Monday will trend downward, with below average temperatures by
Wednesday and Thursday and much more comfortable humidity levels.
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&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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VFR conditions will be in place regionwide today...despite the
cloud cover from a convective complex over Ohio. The increased
clouds will yield some showers but true convection will hold off
until after 22z and should be generally confined to the Southern
Tier. Any site that receives a storm could experience MVFR
conditions for a brief time.

The rain and thunder chances will slowly taper off from west to east
overnight. While most sites will maintain VFR conditions...IFR to
MVFR cigs are expected to develop across the Southern Tier.

Any low cigs from the overnight will improve to VFR by 13z on
Saturday. The remainder of Saturday should feature VFR weather.

Outlook...

Sunday...Mainly VFR...but MVFR cigs possible in scattered showers
and thunderstorms across the Southern Tier during the afternoon.
Monday and Monday night...VFR to MVFR conditions with showers and
thunderstorms likely.
Tuesday...Mainly VFR...but MVFR conditions possible east of Lake
ONtario where some lingering showers and thunderstorms will be
likely.
Wednesday...VFR.
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&&

.MARINE...
Southwest winds in the 10-15 knot range will bring choppy conditions
to Lake Erie and the northeast end of Lake Ontario today through
Saturday, but winds and waves are expected to remain below Small
Craft Advisory criteria. A few scattered thunderstorms may produce
gusty winds and locally higher waves late this afternoon and
evening, and possibly again Saturday afternoon and evening.
Relatively light winds will return Sunday as weak high pressure
moves into the eastern Great Lakes.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...PP/AA
LONG TERM...JM
AVIATION...RSH
MARINE...Hitchcock