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Area forecast discussion 
National Weather Service Buffalo New York
636 PM EDT Thursday Sep 3 2015

Synopsis...
high pressure will build into New England Friday and then along the
East Coast over the Holiday weekend and provide an extended period
of dry weather and very warm temperatures. The next chance of rain
will not arrive until Tuesday when a weak front crosses the region.
The very warm temperatures will last through at least the middle of
next week.

&&

Near term /through Friday/...
a weak/diffuse trough will continue to push south of the area
through this evening...although local mesoscale boundaries are
overwhelming the synoptic boundary in terms of low level
convergence.

Radar imagery shows the most significant convection across Ontario
west of Toronto and across western PA...with our County Warning Area pretty much
dry. The southward moving trough may spark a storm or two in far
southern portions through early evening...but in general expect
the vast majority of the night to be dry.

Expect at least partial clearing overnight in most areas. Fog and
low stratus will form once again...with the most widespread fog in
the typical southern tier river valleys. There may also be an area
of advection fog over Lake Ontario which could push onshore along
the South Shore of the lake. Elsewhere expect just patchy light
fog/br which has been common the past few mornings. Some low
stratus may also form late tonight across the higher terrain of
the southern tier late tonight. A push of somewhat drier low level
air will arrive late tonight...and this should allow fog to clear
earlier than the past few days across the northern half of the
area.

A minor airmass change behind the trough will allow temperatures to drop a
little lower than recent nights...with middle 60s on the lake plains
and around 60 in the cooler southern tier valleys. The north country
will get deeper into the airmass change...with middle to upper 50s
there.

Friday morning the southern tier fog and stratus will burn off by
middle to late morning. This will leave partly to mostly sunny skies as
high pressure builds southeast across Quebec and northern Quebec.
Somewhat deeper moisture will linger across the southern tier and
this will allow diurnal cumulus to form across the higher terrain.
Mesoscale model guidance still suggests a small chance of isolated
convection during the afternoon across Chautauqua County near a
convergence zone just inland from Lake Erie.

Temperatures will remain above normal Friday despite the weak trough
passage today. Expect highs in the middle 80s across lower elevations
and lower 80s on the hills. Northeast flow will keep the South Shore
of Lake Ontario cooler.

&&

Short term /Friday night through Sunday night/...
an anomalously strong upper level ridge will be overhead to start
the Holiday weekend and only slowly move east and dampen out a
little by Sunday night. This will virtually guarantee dry weather
with temperatures about 10f above normal...with highs in the middle
and upper 80s...but well below records which are in the low/middle 90s.

Expect some typical valley fog in the mornings...and possibly some
marine low clouds/fog as well.

&&

Long term /Monday through Thursday/...
as the ridge moves east...the currently strong upper level low in
the Pacific northwest will move across the northern plains and into
Saskatchewan and northern Ontario Monday and Tuesday. Overhead
however...a continued dry spell will continue with slightly lower
daily high temperatures as the ridge continues to slowly loose
its grip over the region.

Eventually...a cold front will mark an initial change in the weather
hinting a return to late Summer conditions...hardly fall though.
Model trends seem to focus on this for Wednesday or Thursday.
However there appears to be a weak initial trough moving through
Monday night or Tuesday that may touch off scattered showers well
before any notable cooldown. Some of the models featured a low
moving by to the northwest of kbuf /ex the 06z GFS/. Will ignore
these as they seem unrealistic when compared to the forecast
pattern. Newer 12z guidance looks more reasonable.

&&

Aviation /00z Friday through Tuesday/...
any diurnal convection will dissipate early this evening with the
loss of daytime heating. Diurnal cumulus will also decrease.
Overnight expect some fog and stratus to develop once again...with
the most widespread fog forming across the southern tier river
valleys and possibly along the South Shore of Lake Ontario with
areas of IFR. Elsewhere expect patchy lighter fog/br with MVFR
visibility. A slightly drier push of low level air will move south out
of Canada late tonight...and this may help to clear the fog before
daybreak across northern portions of the area.

The rest of the fog and stratus across the southern tier will burn
off by late morning Friday. This will leave VFR to prevail for the
rest of Friday with scattered diurnal cumulus developing across the higher
terrain.

Outlook...
Friday through Monday...VFR. Localized IFR in overnight/early
morning fog.
Tuesday...mainly VFR with a chance of showers and storms.

&&

Marine...
high pressure will build across Quebec and northern New England
later tonight and Friday. This will bring a push of moderate
northeasterlies especially on Lake Ontario. Winds and waves will
approach Small Craft Advisory criteria along the South Shore of Lake
Ontario late tonight and Friday morning. Winds and waves will
diminish later Friday afternoon.

High pressure along the eastern Seaboard will then bring an extended
period of light winds generally at 10 knots or less and flat wave
action for the entire Labor Day Holiday weekend. The flat conditions
combined with warm temperatures will provide excellent boating
conditions for the Holiday...although winds will be a little light
for sailors.

&&

Buf watches/warnings/advisories...
New York...none.
Marine...none.

&&

$$

Synopsis...Hitchcock
near term...apffel/Hitchcock
short term...zaff
long term...zaff
aviation...Hitchcock/apffel
marine...Hitchcock

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