Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Buffalo New York
409 PM EST Tuesday Feb 9 2016

Synopsis...
low pressure over the Great Lakes will continue to slowly move east
tonight. As this system moves east...an Arctic air mass will filter
in across the lower Great Lakes with accumulating lake snows into
the weekend. Highs on Saturday will likely struggle to climb
above zero across many locations with dangerously low wind chills.

&&

Near term /through Wednesday/...
regional radars continue to show some scattered light rain and snow
showers moving across central New York. Very minor accumulation is
expected across this region. Otherwise...all other locations
can expect mainly just cloudy skies through the early evening
hours.

An impressive and highly amplified synoptic pattern has developed
over the Continental U.S with a ridge in the west and a deep trough
covering 2/3 of the eastern U.S. In addition to this impressive
pattern...a nearly vertically stacked closed low is currently
positioned over the Great Lakes this evening. It will be this
feature...which has been nearly stationary that will begin to open
up and slowly move east across western New York late tonight and east of
the area by early Wednesday morning. As this low progresses to our
east...increasing moist cyclonic flow and Arctic air will combined
with a middle level shortwave to produce widespread light snow on
Wednesday. It is expected that this feature will produce a few
inches as it moves across the region outside of the lake enhanced
and lake effect snows.

Wednesday...as the colder air filters into the region and deepens
(850 temperatures dropping to -22 to -24c) with lake induced equilibrium
levels rising to 10k feet by Wednesday and Wednesday Night Lake
effect snows will quickly pickup east and southeast of the lakes.
Latest mesoscale models guidance continues to suggest that the
Highest Lake effect snows will be found across the Chautauqua ridge.
Given this...went with a lake effect snow warning for Chautauqua and
Cattaraugus counties. The greatest amounts will likely fall in a
fairly narrow corridor just inland from the lake along the
Chautauqua ridge where totals may reach 8-16 inches. Lesser
amounts will be found across southern Erie where a lake effect
Snow Advisory has been issued. Along with the lake effect
snows...expect temperatures to plummet as colder air rapidly moves
into the region. The high on Wednesday will likely occur in the
early morning hours before turning colder.

&&

Short term /Wednesday night through Thursday night/...
the region will be in northwesterly cold air advection flow during
the period with cooling temperatures aloft increasing lake
instability. However...the specifics will be quite complex with
subtle features determining exactly where the steadiest lake effect
snow occurs. In addition to the lake effect warnings/advisory east
of Lake Erie...a lake effect Snow Advisory has been issued for
southeast of Lake Ontario Wednesday afternoon through Thursday. Now
for the details...

A broad west-northwest flow will be maintained Wednesday night and Thursday.
However...a narrow 500 mb ridge axis is forecast to be across
western New York Wednesday evening before another shortwave crosses
the region later in the night. This will both provide some extra
moisture. Behind this consensus 850mb temperatures drop to around
-22c with the airmass fairly dry. This will make connections
upstream to Lake Huron and Georgian Bay more important for steadier
snows.

Off Lake Erie...expect modest lake effect snows to continue east of
the lake Wednesday evening to intensify with the passage of the
shortwave late Wednesday night and into Thursday morning. Steadiest
snows will be along the Chautauqua ridge and ski country where
upsloping will enhance lift and produce moderate to sometimes heavy
snow. Intensity will diminish Wednesday afternoon...however there
may be a narrow band of steadier snow due to Lake Huron enhancement
which is most likely to be somewhere across Chautauqua County.

Off Lake Ontario...snow will also pick up south of the lake on
Wednesday night...with the passage of the shortwave and with a weak
surface low forecast to track across Lake Ontario. Winds will shift
abruptly to the northwest behind the surface low which will probably
provide a decent snow burst to all areas south of Lake Ontario in
the 1-3 inch range. After this...a west-northwest flow becomes better aligned
with steadier snows in Wayne/north Cayuga/Oswego counties late Wednesday
night and into Thursday. Model guidance differs here with the
nmm/arw high resolution models more aggressive in developing a
convergence band and bringing in some Georgian Bay moisture. The
NAM/rgem are less impressive...but still show decent snows in this
area. Expect day and a half storm totals to push 10 inches in some
areas...which prompted the lake effect Snow Advisory. This area will
have to be monitored with a chance that the band will develop early
or become more intense. Also...model guidance typically struggles in
a northwest flow. Locally heavier snows are possible with a Georgian
Bay connection in Niagara/Orleans/Monroe counties...but forecast
confidence is short of issuing headlines for these areas.

Otherwise...periodic snow showers will produce generally light
accumulations. Temperatures will be below normal with highs in the
teens in most areas. Lighter lake effect snow will continue Thursday
night with limited moisture and wind shear. Winds will shift from
west-northwest to west-southwest which will lift what bands are in place northward with
additional but modest accumulations possible east of the lakes.

&&

Long term /Friday through Tuesday/...
Friday afternoon the Arctic cold front will approach...the cross the
region Friday evening. With this will be a shortwave which will
provide a bit more moisture with lake effect snows expected to
briefly pick up in a west-southwest flow ahead of this. Expect lake effect snow
to intensify east of the lakes just ahead of the Arctic front
possibly producing decent accumulations...then move south overnight
and break apart into multiple bands south of the lakes as boundary
layer flow becomes northerly. The boundary itself could also produce
a decent burst of snow.

Temperatures will plummet behind the front on Friday night and last
through Saturday night. The instability will be extreme with such a
cold airmass...but all airmasses this cold are also very dry. The
dry air...short northerly fetch...and poor cloud microphysics in the
bitterly cold air will likely keep accumulations relatively minor
for Saturday through Sunday. The inland extent of lake effect snow
will diminish with diminishing winds Saturday night and
Sunday.

The big story this weekend will be the extreme cold. Medium range
guidance remains consistent in bringing the coldest airmass of the
winter by far into the lower lakes and New England. Both the GFS and
European model (ecmwf) take 850mb temperatures down to around -32c on Saturday. To put this
in prospective...the coldest temperature ever recorded at 850mb on a
kbuf sounding in the month of February is -28c...and the coldest
ever recorded for any month is -32c. This frigid airmass will keep
highs in the lower single numbers on Saturday...and if the timing
works out with the core of the cold crossing during the day highs
may not get above zero. As a side note...this may not break records
for the coldest high because the temperature early Saturday morning
just after midnight will probably be much warmer than the daytime
high will be.

Lows Saturday night will be below zero everywhere...and 20 below or
better across the north country with no lake influence. The
combination of bitter cold and wind will produce dangerously cold
wind chills.

The core of the cold begins to move off by Sunday afternoon with a
rapid warm-up to near average by Monday and Tuesday. The GFS/European model (ecmwf)
differ quite a bit with the GFS faster/colder/weaker with the next
system. For now will use a blend...with a broad period of chance
probability of precipitation Monday and Tuesday to account these timing differences. It will
probably be cold enough for snow...however if the European model (ecmwf) verifies
some rain is even possible.

&&

Aviation /21z Tuesday through Sunday/...
MVFR ceilings will continue through the evening hours for western
New York...with slowly deteriorating conditions toward IFR tonight into
Wednesday. East of Lake Ontario however...expect a period of
improving/VFR conditions after an area of snow moves northeast out
of the region...before IFR conditions return later Wednesday.

Outlook...
Wednesday through Thursday...MVFR/IFR in periods of snow.
Friday...MVFR. A chance of snow showers.
Saturday and Sunday...VFR/MVFR...chance of snow showers.

&&

Marine...
a stationary storm system will be open up and move east tonight.
This system will bring strengthening winds on Lake Erie this
evening and tonight. Winds and waves will likely reach Small Craft Advisory levels
on Lake Erie by late this evening... and will certainly be in place
tonight. Although...winds will remain relatively light on Lake
Ontario.

On Wednesday...the large storm system will push east across New
England and the Canadian Maritimes. This will promote fresh to
strong westerlies on both lakes Erie and Ontario...which will become
more northwesterly Wednesday night. A Small Craft Advisory has also been issued for
Lake Ontario starting Wednesday. In addition to the Small Craft Advisory...an Arctic air
mass will filter into the lower lakes and combined with strong winds
will likely result in significant freezing spray.

&&

Buf watches/warnings/advisories...
New York...Lake effect Snow Advisory from 1 PM Wednesday to 6 PM EST
Thursday for nyz004>006.
Lake effect snow warning from 11 PM this evening to 4 PM EST
Thursday for nyz019-020.
Lake effect Snow Advisory from 11 PM this evening to 4 PM EST
Thursday for nyz085.
Marine...Small Craft Advisory until 6 PM EST Thursday for lez040-041.
Small Craft Advisory from 4 PM Wednesday to 6 am EST
Friday for loz043>045.
Small Craft Advisory from 1 PM Wednesday to 6 am EST
Friday for loz042.

&&

$$

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

National Weather Service Glossary of Abbreviations