Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 291923
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
323 PM EDT FRI JUL 29 2016

.SYNOPSIS...
A few showers will be possible across the Southern Tier this
afternoon before tapering off early this evening. Showers and
possibly a few thunderstorms will be possible again tomorrow across
the Southern Tier with more widespread activity expected on Sunday
as an area of low pressure crosses the region. The enhanced cloud
cover and persistent northerly flow will keep temperatures near
normal through the weekend before high pressure and increasingly hot
weather returns next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
Broad anti-cyclonic northerly flow around an area of high pressure
centered over the Western Great Lakes is keeping much of the
forecast area dry and mild, at least compared to the very warm
temperatures we have been seeing of late. This northerly flow is
also keeping the limited convection we have seen this afternoon
confined mainly to the Southern Tier and Northern PA, closer to a
stalled frontal boundary over northern OH and PA. Expect any
remaining showers and isolated storms to remain confined to this
area before winding down around sundown.

Aside from a few lingering showers early this evening, it should be
a quiet night across the forecast area with mid-level clouds
increasing from the west later tonight as an upper level trough
approaches the Lower Great Lakes. Activity will once again be
confined primarily to the Southern Tier, closer to the frontal
boundary that will still remain stalled over PA.  Temperatures
through the period will run close to normal with lows in the upper
50s to mid 60s overnight and lower 80s Saturday, as a combination of
cooler northerly flow and cloud cover will combine to depress
readings as compared to recent values.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
A broad mid level trough over the central Great Lakes on Saturday
night will move to the Lake Ontario basin and Saint Lawrence Valley
on Sunday night, then to northern New England by Monday evening.
This will be reflected at the surface as an ill-defined region of
low pressure along and north of the Ohio Valley, moving eastward
across Pennsylvania with the track of the upper trough. This system
will bring some beneficial rain over the weekend, although the slow
moving and diffuse nature of large scale ascent will make timing and
placement of more organized rainfall difficult.

The first half of Saturday night our region will be between waves,
with many areas becoming mainly dry. Scattered showers will linger
across the Southern Tier where deeper moisture and weak low/mid
level deformation will remain. Overnight lows will range from the
upper 50s across higher terrain to the lower to mid 60s for the rest
of the forecast area. Easterly breezes will reduce or remove any
warming influences of the lakes Saturday night.

Late Saturday night and Sunday the mid level trough will slowly
cross the region, with  better differential PVA supporting more
robust large scale ascent. There continue to be some minor
differences in the details of this evolution amongst various
operational models, particularly GFS and ECMWF, but enough
confidence is there in the overall pattern to support increasing
POPS into the likely range in most areas Sunday. Some limited
instability will develop by afternoon, supporting scattered
thunderstorms as well. This system has potential to bring some
beneficial rain to the region, although the heavier amounts are
likely to remain unevenly distributed and tied to areas of
convection. The clouds and showers will keep temperatures down, with
upper 70s or near 80 at lower elevations and mid 70s higher terrain.

Sunday night the mid level trough will meander slowly east into
eastern NY and western New England, while the surface low moves to
eastern PA and southeast NY. More organized showers and a few
scattered thunderstorms will focus on the eastern Lake Ontario
region overnight, with showers slowly tapering off from west to east
across the remainder of the area as better forcing and moisture
shift eastward.

The passage of the upper trough axis on Monday will bing about one
last chance for precip from this pattern, limited mostly to Northern
and Central New York. Skies will clear through the day from west to
east and north to south, as the upper trough exits the region to
the east. High temperatures will be in the middle 70s to the lower
80s with more comfortable and less humid conditions. High pressure
building in from the west will bring drying and clearing over the
entire region with overnight low temperatures in the upper 50s to
the middle 60s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Upper level ridging will build into the Great Lakes during this
period as the eastern Canadian trough breaks down, although that
appears likely to redevelop by the end of the period or just beyond.
Regardless, it does look like the large scale pattern is suggestive
of convective complexes developing within the northern periphery of
the growing heat/instability dome, which will be shifting
eastward with time. The growing ridge will more than likely keep
these complexes north of the region. Therefore, the region we
will have to wait until the ridge shifts far enough to the east to
allow a medium range consensus frontal boundary to approach by the
end of the period, for the next chance for rainfall.

Temperatures will steadily warm through the period as the ridge
builds and a southwesterly return flow becomes established.
Most high temperatures during the period should reach the mid to
upper 80s, with some potential for lower 90s if the warmer solutions
verify.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions will persist through the next 24 hours. A few
disorganized showers and an isolated thunderstorm will be possible
across the Southern Tier this afternoon with activity tapering off
around sundown. Mid-level cigs will move in from the west later
tonight as an upper level trough approaches the region. This trough
will bring a chance of showers, with a few thunderstorms also
possible, to the forecast area on Saturday from 15Z onwards.
Activity should be mainly confined to the Southern Tier, in the
vicinity of a stalled frontal boundary.

Outlook...

Saturday Night through Monday...Mainly VFR with a chance of showers
and thunderstorms.
Tuesday and Wednesday...VFR.

&&

.MARINE...
Waves have diminished on the lakes this afternoon as northerly flow
has relaxed, allowing for the expiration of all marine headlines.
Persistent northeasterly flow will maintain a light to moderate chop
on the lakes this weekend, though waves should remain below advisory
levels as the pressure gradient will remain relatively weak as a
weak area of low pressure passes to the south of the lakes.
Otherwise, high pressure returns to the region next week, ensuring
generally tranquil conditions on the lakes.

&&

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

&&

$$

SYNOPSIS...WOOD
NEAR TERM...WOOD
SHORT TERM...WCH
LONG TERM...TMA
AVIATION...WOOD
MARINE...WOOD



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