Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 260829
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
429 AM EDT FRI AUG 26 2016

.SYNOPSIS...
High pressure will build into the region today and Saturday with
a return to dry weather while temperatures remain above normal. A
weak cold front may produce a few showers and thunderstorms late
Sunday before high pressure returns for early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A weak cold front which is across Western New York early this
morning will push southeast and through the entire region which
will bring in drier and slightly cooler air into the region.
Low moisture ahead of this will result in low clouds and fog
through about mid morning.

High pressure across the mid-western states will ridge into the
region this afternoon. Temperatures will only be a little bit
cooler than yesterday with highs mainly in the lower 80s.
However, dew points will be notably lower with these in the lower
60s which will make it feel much more comfortable than yesterday.

The axis of the high will shift across the region tonight,
providing mostly clear skies and light winds. This will result in
good radiational cooling conditions, which is likely to allow
temperatures to drop a bit cooler than consensus model guidance.
Lows will range from the mid- 50s across the interior valleys to
the lower 60s across the lake plains. This also is likely to
result in valley fog across the Western Southern Tier.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Shortwave ridging building over the region will allow surface high
pressure to build over the region early in this period. Skies will
be mostly clear across the region early on Saturday, but increasing
high cloudiness is expected as a series of weak short waves/
vorticity maxima pass across the region ahead of a more pronounced
wave over Canada. Seasonal temperatures in the upper 70 to mid 80s
expected for Saturday.

The shortwave riding the periphery of the upper high centered
over the southern U.S. will pass though Michigan into southern
Ontario Saturday night into Sunday. This should allow for further
spread of the mid and high level cloudiness, and the latest model
forecast soundings keeping lower levels dry through Saturday night.

GFS and ECMWF are about 6 hours faster with the onset of
precipitation on Sunday than previous model runs. A strong surge of
high Theta-E air will arrive during the day on Sunday, accompanied by
a linearly stretched vorticity max during the peak heating of the
afternoon. Outside of lake breeze boundaries, there will be little to
drive surface convergence to initiate convection, but the right rear
quadrant of a 90kt 250mb will enhance broad scale vertical motion
over the Eastern Great Lakes and NY during the afternoon. A surface
trough will approach from the north during the evening and
convection should be pushed southward as well, exiting the region
overnight.

Sunday should be quite a hot day with 850mb temperatures nearing
+20C. This will translate into highs in the upper 80s across the
higher terrain to the lower 90s across the lake plains. Even as the
surface trough crosses the region on Sunday night, there will be
little if any cooling associated with the trough, thus overnight
lows will not differ much from previous nights and remain in the
middle to upper 60s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As we move into the new week, the cold front moves south of the
forecast area on Monday. There may still be a slight chance of
afternoon showers and thunderstorms, but this is a very low chance
as nominally cooler but considerably drier air filters in from Canada
and surface high pressure moves overhead.

After Monday night, a decent amount of uncertainty creeps into the
forecast, as the next shortwave upstream scrapes along the top of
the mid-level ridging parked over the Ohio Valley and Mid-Atlantic
states. Global models differ on the strength both of this ridging
and the shortwave and the associated surface cold front...but in
either case given the prevailing WNW flow across the Great Lakes,
this feature will not have a lot of moisture to work with and as
such will stick with just a slight chance of showers for Tuesday.
The front will push through the region on Tuesday night, with
chance of showers and lower chance of thunder.

Regarding temperatures, with the cool front moving through Sunday
night/Monday, we should see readings drop back closer to normal on
Monday, with highs in the lower 80s. However, with a generally flat
upper level pattern in place across the country and a jet stream
solidly confined to north of the border for the foreseeable future,
temperatures are likely to remain above average well into next week,
with highs in the low to mid 80s and lows in the low to mid 60s, or
around 5 degrees above average, through much of the week. There is,
however, a pattern change advertised by GFS and ECMWF with cooler
conditions possible for the end of the week...stay tuned.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
The main concern for aviation is fog and stratus development early
this morning. There is lots of low level moisture in place and
this has been pooled up just ahead of a cold frontal boundary
which will move across the region through around 11Z. This will
result in a period of pre-frontal MVFR/IFR conditions. Upstream
observations show a brief improvement behind the front, but as
winds drop off there still will be a narrow window for fog to
develop to the west at BUF/IAG/JHW. Expect the lowest conditions
at JHW where any clearing is likely to be quickly followed by
ground fog.

Fog and stratus should dissipate through mid-morning, giving way
to VFR conditions. After this there is high confidence in VFR
conditions this afternoon and evening as high pressure builds into
the region.

Expect valley fog to form tonight, which should mainly impact the
JHW terminal.

Outlook...

Saturday and Sunday...Mainly VFR.
Sunday night and Monday... Mainly VFR with a chance of showers
and thunderstorms.
Tuesday...VFR.

&&

.MARINE...
High pressure will build across the region with fair weather and
fine boating conditions expected through the weekend. A weak cold
front may bring some showers or thunderstorms late Sunday.

&&

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

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...WCH
LONG TERM...WCH
AVIATION...APFFEL
MARINE...APFFEL



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