Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Buffalo New York
354 PM EDT Tuesday Sep 16 2014

Synopsis...
an area of high pressure will build east across the region bringing
cool and dry conditions through Wednesday. A weak cold front will
then cross the region Wednesday night into Thursday morning bringing
a slight chance for rain showers...with a reinforcing shot of cooler
air behind the boundary for Thursday and Thursday night as high
pressure once again builds across the region through the end of the
week. A complex frontal system is then forecast to cross our region
late in the weekend bringing chances for showers.

&&

Near term /through Wednesday/...
the broad upper level trough will remain parked over the northeast
through the period keeping temperatures cooler than
average...however surface high pressure building in from the west
will keep conditions dry across the region.

Cool temperatures aloft combined with lingering low level moisture will
keep some diurnal cumulus around through early evening making for
partly to mostly sunny skies across the area...with the most sun
being seen right along the lakeshores thanks to lake shadows.

Tonight high pressure over the Midwest states will ridge east across
the lower Great Lakes. Expect this to trap some low level moisture
beneath a subsidence inversion providing some scattered clouds along
and inland from the lakes...with thicker cloud cover possible across
inland areas of the southern tier thanks to upsloping. Some patchy
River Valley fog will again be possible across the southern tier as
well...depending on how dense the cloud cover becomes late tonight.
The added cloud cover will help keep overnight lows a bit warmer
with lows only sliding back into the low to middle 40s...with a few
upper 30s possible across the Tug Hill and western Adirondacks.

As mentioned above...the broad upper level trough will remain parked
overhead Wednesday. Meanwhile surface high pressure will drift
southeast of the region during the course of the day providing
another day of dry...but continued cool weather. Expect some diurnal
cumulus during the afternoon hours again Wednesday inland from the
lakes...with some middle and upper level cloudiness overspreading the
northcountry out ahead of an approaching cold frontal boundary.
Temperatures should be a couple degrees warmer as 850mb temperatures
climb from around +4c to +6c by the afternoon. This will support
highs in the lower to middle 60s across much of the region...with a few
upper 60s not out of the question across the typically warmer
locations.

&&

Short term /Wednesday night through Friday night/...
an upper level system now evident on water vapor imagery across the
Canadian prairies will sag into the region Wednesday night. Latest
models suggesting a weak frontal boundary will drop across the
region Wednesday night. Best forcing looks to remain on the cool
side of the front in close proximity to the surface wave moving
across Ontario/southern Quebec. Would not rule out a few showers
across the north country...but for the most part this front should
come through dry.

In response to strong 1000-500mb geopotential height rises swinging
across southern Canada...a very stable anticyclone is forecasted to
drop southward through the Great Lakes behind the front Thursday and
Friday. Incoming air mass looks quite dry...but also quite chilly
with 850 mb temperatures dropping to near -2c by Thursday night.
Thursday night looks to be the first widespread frost of the season.
Although will have to deal with moisture fluxing off Lake Ontario
with the potential for some lake cloudiness holding up temperatures.
The North County should be clear with freezing temperatures much
more likely.

The Arctic high and associated cold air will move off to the east on
Friday. This will allow for an increasing southerly return flow to
set up with temperatures moderating closer to normal.

&&

Long term /Saturday through Tuesday/...
minor upper level ridging during the weekend will allow temperatures
to warm above normal levels as the upstream upper trough pushes to
the northeast. Temperatures in the lower to middle 70s...possibly even
warmer look likely for both Saturday and Sunday ahead of the
approaching surface cold front. Still some uncertainty as to exactly
how the weekend system will play out. Classic shortwave ridging
should protect the area from precipitation Saturday and possibly
Sunday...if the slower solutions verify. At this point...the model
consensus would suggest the best chance for showers and possible
thunder continues to be in the Sunday afternoon into the early
Monday time frame with the passage of the cold front. Front looking
to tap into some tropical moisture across the southwest Continental U.S....but
it appears that the cold front will move through quick enough to
limit heavy rainfall potential.

For early next week...upstream teleconnections support the
redevelopment of the longwave trough over the eastern Continental U.S....with
the trough axis east of Hudson Bay extending south into the eastern
Continental U.S.. with most of the extended models and ensemble members
supporting this solution this will set the stage for some very
chilly air to make a return early next week.

&&

Aviation /20z Tuesday through Sunday/...
widespread VFR flight conditions seen across the region late this
afternoon...with diurnal cumulus providing just some low VFR ceilings
around 4k feet across the southern tier including kjhw. Just few to
scattered low clouds elsewhere...keeping VFR conditions locked in for the
rest for the afternoon.

Tonight high pressure will ridge east from the Midwest states. This
may trap enough moisture for some mainly VFR low level scattered
clouds inland from the lakes overnight...with some MVFR/isolated IFR
ceilings possible across the higher terrain of the southern tier
including kjhw. River Valley fog will again be possible across the
southern tier as well...depending on how dense the cloud cover
becomes late tonight....possibly impacting the kjhw terminal.

Surface high pressure will drift southeast of the region during the
course of the day Wednesday providing another day of dry...but
continued cool weather. Any early morning MVFR/IFR ceilings/visibilities across
the inland southern tier should improve to VFR by middle morning...and
last through the end of the period. Do expect some diurnal
cumulus to develop by early afternoon Wednesday inland from the
lakes...with some middle and upper level cloudiness starting to
overspread the northcountry out ahead of an approaching cold
frontal boundary...however VFR conditions are expected through the
remainder of the period.

Outlook...
Wednesday night through Saturday...generally VFR. Some patches of
MVFR ceilings Wednesday night. Some valley fog with localized IFR flight
visibilities across the southern tier Friday and Saturday morning.
Sunday...VFR/MVFR chance of showers.

&&

Marine...
westerly winds will increase to 15-20 knots across the eastern
and southeastern Lake Ontario near shore waters later this evening
behind a weak surface trough. Thus have opted to hoist a Small
Craft Advisory between Mexico Bay and the Saint Lawrence
River...and will continue the Small Craft Advisory between Sodus
Bay and Mexico Bay. Otherwise winds and waves in other zones will
remain below small craft criteria. Winds and waves will gradually
subside late tonight into Wednesday morning and remain below Small Craft Advisory
through Wednesday night.

&&

Buf watches/warnings/advisories...
New York...none.
Marine...Small Craft Advisory from 8 PM this evening to 2 am EDT
Wednesday for loz044-045.

&&

$$

Synopsis...jm
near term...jm
short term...tma
long term...tma
aviation...jm
marine...jm

National Weather Service Glossary of Abbreviations