Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 251048
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
648 AM EDT THU AUG 25 2016

.SYNOPSIS...
A pair of mid level disturbances will then cross the region
through tonight which will provide a couple rounds of showers and
a possibly a thunderstorm. High pressure will then bring a return
to dry weather for Friday through most of the weekend, with
temperatures remaining above normal.

&&

.NEAR TERM /THROUGH TONIGHT/...
The region will remain in a warm and moist flow with a fairly
zonal WSW flow aloft and the jet axis to our northwest across
Lake Superior. A weak cold front is forecast to drop across the
region tonight, but this will bring only slightly cooler and drier
air in its wake.

A mid-level wave will track across the region this morning. The
Buffalo VWP shows a modest LLJ associated with this with this
helping a line of showers hold together by providing lift and
advecting moisture. Similar to HRRR guidance, expect these
showers to continue to weaken through late morning before exiting
east of the cwa late morning.

After this there should be a period of fair weather with some
sunshine late this morning and early afternoon as drier mid-level
air and subsidence builds behind this departing wave. This is
supported by upstream IR imagery, and a consensus of mesoscale
guidance. The only concern through this afternoon is a small
chance for showers to develop along the lake breeze boundary
southeast of Lake Ontario and east of Lake Erie. Otherwise today
will be rather muggy with highs in the 80s and dew points around
70.

Another round of showers and a few thunderstorms is likely to
develop ahead of the front. Instability will be limited ahead of
this, with CAPES long and thin due to warm air in the mid-levels.
Even so, there may be enough momentum from upstream convection to
advect into Western areas this evening before weakening as it
moves east into Central New York. This trend is generally captured
by mesoscale guidance, but there is disagreement on the track of
this which lowers forecast confidence. In general, model
consensus suggests the best chance for this is across the Western
Southern Tier early this evening. There is a marginal risk for
severe weather with this, with a modest 30kt flow at 700mb
providing enough shear to support a few strong to severe storms.
With precipitable water values forecast to be near 2 inches these
also could contain heavy rain, but the progressive nature of this
should help mitigate the risk for flooding.

Showers will end from west to east late tonight, with some patchy
fog possible. Lows will be in the upper 60s to lower 70s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The forecast area will see a return to a quiet and dry regime moving
into the weekend as a cool front slides across the area Friday
morning and an amplifying upper level ridge moves overhead, ensuring
plenty of sunshine for Friday and Saturday. We will see temperatures
in the upper 70s to lower 80s Friday and Saturday. Drier air and
clear skies will allow for cooler temperatures Friday night, with
lows in the upper 50s to lower 60s, while by Saturday night
southerly flow returns, signaling the return of increasingly warm
and humid air to the region, reflected in lows in the mid to upper
60s along the lake plains. There will be valley fog forming across
the Southern Tier, with the clear skies and cooler temperatures,
moisture supplied by the warmer waters of the rivers and lakes of
the region. There may also be a return of valley fog on Saturday
night, but to lesser degree with increasing clouds blanketing the
area and blocking the radiational cooling.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Surface ridging over the southeast will relax a bit across the
region as a shortwave moves through the Upper Great Lakes into
Canada and its trailing cold front approaches the area to begin this
period.

Sunday should be the hottest day with 850mb temperatures nearing
+20C. This will translate into surface highs in the upper 80s across
the higher terrain to the lower 90s across the lake plains. In
addition to the heat, humidity levels will also ramp up as southerly
flow picks up and draws moisture up across the region. This will
introduce a chance of a few afternoon showers and thunderstorms
inland from the lakes especially along any lake breeze boundaries.
Sunday night, as the front begins to enter Western and North Central
New York expect increasing chances for additional showers and
thunderstorms.

Looking into next week, the front is forecast to slowly slide south
through Western and North Central New York Monday. Although, how
fast this occurs and how far the front pushes south is uncertain at
this point. The GFS moves the front out with surface high pressure
building into the region with mainly dry weather through Wednesday.
The ECMWF stalls the front just to our south over Pennsylvania which
will keep a slight chance of a few showers and thunderstorms across
the Southern Tier through late Tuesday. Overall, despite the
differences it looks to be primarily dry after Monday with high
temperatures above normal, low 80s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
An area of showers driven by a mid-level wave will continue to
track to the east and weaken this morning. Expect a couple hours
of MVFR- IFR conditions to develop behind this wave as winds
aloft diminish and low level moisture pools. This should mix out
late this morning, with improving conditions during the day.

Mainly VFR conditions should persist until the next wave arrives
late afternoon or early evening. This will bring another chance
for showers and possibly a thunderstorm. Showers and storms will
move from west to east.

BUFKIT forecast soundings suggest there may be some low moisture
trapped beneath an inversion late tonight. This may result in
some fog, especially in areas which do get rain today and in the
typical Southern Tier valleys.

Outlook...

Friday thru Sunday...Mainly VFR.
Monday... Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
Southwesterly winds will increase at the northeast end of Lakes
Erie and Ontario early this morning, and again this afternoon. In
each case, winds will approach but are expected to fall just short
of Small Craft Advisory levels. A cold front will ease its way
across the Lower Lakes tonight. This feature will bring a few
rounds of showers and thunderstorms through tonight, which may
produce locally higher winds and waves.

After this high pressure will build across the region with
fair weather and fine boating conditions expected for Friday and
Saturday.

&&

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

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...WCH/WOOD
LONG TERM...AR/WCH
AVIATION...APFFEL
MARINE...APFFEL



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