Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 311453
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1053 AM EDT WED AUG 31 2016

.SYNOPSIS...
A cold front will cross the region today bringing a couple of rounds
of scattered shower and thunderstorms across the region through this
afternoon and early evening. Cooler and drier air moving in behind
the front will usher in more comfortable temperatures through the
rest of the week as high pressure builds across the region before
summer heat returns for the Labor Day weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Numerous rain showers and only isolated thunderstorms will continue
to trek southeastward across the region for the remainder of the
morning and into the early afternoon. This is ahead of an
approaching cold front, and is apparently the result of a broad
region of lift enhance by the proximity of the right entrance region
of an upper jet streak. A couple regions of stronger convection
earlier this morning have diminished in strength but there are still
some heavier rain showers, showing as 40-45dBZ radar reflectivity
signatures.

The surface front will approach the forecast area from the northwest
this afternoon. The boundary will likely be slowed in its
southeastward progression by the combined effect of the lower Great
Lakes lake breezes. Nevertheless, expect the abrupt windshift to the
northwest to approach the Niagara Frontier early this afternoon. The
combined enhanced low-level convergence from the aggregate lake
breeze boundaries / surface cold frontal boundary, will focus
another round of scattered showers and thunderstorms that should
develop near Niagara and Orleans counties and track off to the south
and east with the frontal push. While the Niagara Frontier mays see
the best chances for convection with the frontal passage, have
maintained scattered PoPs across much of western and north central
NY this afternoon. The lack of opportunity for strong diurnal
destabilization and overall lackluster deep-layer shear should keep
thunderstorms from becoming strong today. If a stronger storm
capable of strong wind gusts were to develop, the best chance would
be in the Niagara Frontier where the combined lake breeze / frontal
boundary would locally enhance low-level helicity.

Temperatures today will be held to the upper 70s in the higher
terrain to the low 80s across the lake plains. Despite 850 mb
temperatures to around +14/+15C, the plentiful cloud cover should
help limit daytime heating.

Tonight, the marginal daytime instability will wayne with nightfall
and the cold frontal boundary will move south and eastward across
the region with a marked northwest to north wind shift this evening
and overnight. Thus any lingering convection will shift out of the
area and weaken with time. The airmass will slowly cool behind the
frontal passage, with 850 mb temperatures down to around +9/+10C by
sunrise Thursday. Thus temperatures will slowly fall through the 60s
overnight, reaching lows in the upper 50s in the higher terrain to
the lower 60s across the lake plains.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
Expansive area of cool Canadian high pressure will start to build
into the region Thursday. Lagging upper level trough axis will slide
across the area with some risk for a few isolated showers. For most
areas, Thursday will be mainly cloudy, especially across the Finger
Lakes and Southern Tier as a northerly component maintains an
upslope flow. Steady cold air advection will hold temperatures in
the lower to mid 70s, but probably only in the 60s across the higher
terrain of the Southern Tier, Finger Lakes and the Tug Hill.

The center of the expansive surface high will make its way to the
Great Lakes by Thursday night. This will set the stage for favorable
radiational cooling within a fresh Canadian airmass helping
overnight temperatures to drop well into the 50s away from the
lakes, with parts of Lewis County and the Southern Tier likely
falling into the 40s.

On Friday, broad ridging will be centered over the Mississippi
Valley while the associated surface high remains over the Great
Lakes. This will ensure that cool dry weather will persist, with 850
mb temperatures around 9c providing a second day of high
temperatures in the lower to mid 70s, and 60s across the higher
terrain.

The surface high will drift to the Lower Great Lakes by Friday
night, allowing for the coolest night of the forecast period. Nearly
ideal radiational cooling under clear skies will allow the
temperatures to fall into the lower to mid 40s across the majority
of the Southern Tier as well as in Lewis County, with lows within a
few degrees of 50 elsewhere.

Saturday will then feature absolutely beautiful weather across our
region, as ridging at levels will couple with a Canadian airmass to
produce sun filled skies and comfortable conditions. Temperatures
will top out in the upper 70s in most areas, while dew points will
remain within a few degrees of 50. Simply outstanding weather for
outdoor activities.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
This period will feature a return to mid summer warmth as our
forecast area will be squarely under a ridge...sandwiched between a
broad based trough over the western half of the country and a
tropical system off the East Coast. This very high confidence
forecast will include dry weather as well. The dry and warm
conditions will only enhanced by strong subsidence that would be
found over our region if the medium range ensembles are correct in
their general position of the tropical system off the Northeast
Coast.

Temperatures during this period will range from the mid and upper
80s for most areas by day to the mid and upper 60s most nights.

Looking further down the road at the remainder of next week...the
presence of a strong jet across the North Pacific should keep a low
amplitude trough in place over the western conus.  This will favor a
downstream ridge over the eastern seaboard with a persistent
southerly flow over the Lower Great Lakes. The strong zonal
Pacific flow will also help to block any attempt by chilly
Canadian air from making its way south of the border. The result
will be a continuation of above normal temperatures through the
week.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will continue to prevail with increasing and lowering
mid and high level cigs. Scattered showers and thunderstorms will
move across the region this morning, with perhaps only localized
MVFR restrictions in the stronger storms.

Moving into later this morning, and early this afternoon, we will
continue to see scattered showers and thunderstorms along the
frontal boundary as it pushes southeast across the forecast area,
however prevailing conditions should remain VFR outside of any
cells. Any activity should be scattered in nature so have only
include VCSH/VCTS for now. Winds will retain a west-southwest
component throughout the day, with veering to the west-northwest not
taking place until after frontal passage late Wednesday.

Outlook...
Wednesday Night and Thursday...Mainly VFR with a slight
chance of showers.
Friday through Sunday...VFR.

&&

.MARINE...
A cold front will drop south across the lakes today, bringing a
scattered showers and thunderstorms. Conditions become marginally
favorable for waterspouts with any showers and thunderstorms today,
and thus have included a chance from waterspouts in the marine
forecast.

Freshening northerly flow behind the front will gradually build the
chop on the south sides of the lakes tonight into Thursday. By
Thursday afternoon, waves may approach 4 feet, and a small craft
advisory may be required, particularly should the gradient tighten
as high pressure builds across the central Great Lakes. Waves should
subside as the high pressure moves overhead Friday.

&&

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

&&

$$

SYNOPSIS...CHURCH
NEAR TERM...CHURCH/WCH
SHORT TERM...TMA
LONG TERM...RSH
AVIATION...CHURCH
MARINE...CHURCH



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