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fxus61 kbgm 131149 
afdbgm

Area forecast discussion
National Weather Service Binghamton New York
649 am EST Wed Dec 13 2017

Synopsis...
it will be bitterly cold today, with wind gusts to 35 mph and
wind chills below zero at times. Lake effect snow will continue,
mainly in central New York, yet with at least scattered snow
showers and flurries elsewhere. Any snow will be very dry, prone
to blowing and drifting. Late tonight, a fast moving clipper
will bring a quick light snow to much of the area.

&&

Near term /through Thursday/...
355 am update...
main concerns are continued lake effect snow today mainly in
central New York, and gusty winds areawide causing wind chills
below zero at times this morning. Also, a small clipper will zip
through tonight with a quick light snow for northeast
Pennsylvania and much of central New York, followed by lingering
lake effect again east-southeast of Lake Ontario.

Arctic air mass has overtaken the region with our coldest
temperatures since last March. Almost the entire lowest 12
thousand feet now is at ideal dendritic growth temperatures (12
to 18 c degrees below zero), and thus pretty much every cloud
is generating snow crystals. Lake Ontario band was initially
down its long axis and focused on Tug Hill in the evening, but
winds are now veering west-northwest which has transitioned it
into multibands. Also, 700mb low has closed off, and aloft some
Atlantic moisture is wrapping around and back into some of the
Lake Ontario bands, enhancing them via the seeder-feeder
phenomenon. For that reason and also blowing snow, visibility
is under a mile at times in the greater Syracuse area. 500mb low
is slightly further west, almost directly over The Finger
lakes. This is the core of very cold air aloft, which has also
yielded very steep lapse rates in the lake moisture layer,
helping to keep lake effect snow going strong.

As the 500mb low shoots east later this morning and very dry
air gets further entrained over the area, lake effect will
diminish in intensity. By afternoon the accumulating snow will
primarily be confined to Onondaga- Madison-Oneida-Otsego
counties. Until then, dry fluffy snow accumulations will
continue to work down across the ongoing Winter Storm Warning
area and portions of the advisory counties as well. Outside of
the advisory and warning counties, at least scattered snow
showers and flurries will occur for basically our whole area.
All of it will be very prone to blowing and drifting, because of
the very fluffy nature to the crystals and frequent gusts of
25-35 mph. Wind chills are also already near zero areawide, and
in many cases, single digits below zero. That will continue
through the morning. Lower elevations will manage to barely get
into the 20s for temperatures today, but much of the area will
be stuck in the mid to upper teens for highs.

No rest for the weary; winds diminish this evening and lingering lake
effect winds down, but another small clipper will already be
inbound. The associated low is currently dropping through the
upper Midwest, and will be over Ohio by this evening. Overnight,
the low will quickly track through Pennsylvania while weakening.
However, with the very cold air mass only needing a very slight
nudge of lift to generate snow crystals, that will indeed happen
for the majority of the area. At least a half inch to inch
coating of light fluffy snow is thus expected overnight for the
entire area; closer to 1-2 inches near the low track in
northeast PA. The New York thruway corridor could also end up in the
1-2 inches range because of lake enhanced moisture. Temperatures
will not move very much due to clouds and temporary warm air
advection ahead of the clipper; lows in the teens except single
digits in northern Oneida County.

&&

Short term /Thursday night through Saturday/...
3 am Wednesday update...
continue to be under a broad and deep upper level trough across
the eastern half of the country. A west northwest low level
flow will have a Good Lake Ontario band into the northern
counties including Syracuse Thursday evening. This will lift
north towards midnight as the flow shifts to southwest ahead of
the next synoptic system. Snowfall from the lake band will be a
few inches mostly in the evening.

A stacked low drops south southeast into the western Great Lakes
Friday morning then to New York Friday night. A widespread light snow
of an inch everywhere to as much as 3 in central New York Friday
afternoon to Saturday morning. The upper level trough will move
quickly through at the same time allowing for some warming in
the long term.

Temperatures in the 20s for highs again with lows in the teens.
Less windy than yesterday to Thursday.

&&

Long term /Saturday night through Tuesday/...
3 am Wednesday update...
little change to the long term. Followed wpc guidance. Models
in good agreement. Slow moderation as the deep upper level
trough weakens. A stalled front across the Great Lakes will
provide chances of continued snow showers and flurries in
central New York. A front will cross Sunday night with some light
snow. More light snow is expected Tuesday to Wednesday as
another cold front moves through. This will be stronger but
still moisture starved. The upper level trough axis will move
through Tuesday night and Wednesday with more Arctic air.
Temperatures closer to normal with highs in the 30s this period.
Low temperatures start in the teens Saturday night but rise
into the 20s the rest of the period.

&&

Aviation /12z Wednesday through Sunday/...
streamers of lake effect snow will persist off the Great Lakes
today, and even The Finger lakes at times this morning. Between
lake effect bands, mostly VFR conditions will occur or at worst
a high end MVFR deck. But within the bands, because this Arctic
air mass has temperatures in the cloud layer at ideal values for
snow Crystal growth, IFR visibility will become common, and in
the case of ksyr below alternate minimums at times. Winds will
be west to west-northwest into mid teens knots sustained with
gusts reaching to 20-30 knots during the daytime hours. This
will also pose a blowing-drifting snow problem, itself perhaps
reducing visibilities especially ksyr- krme, since the snow is
very dry and fluffy. Though lake effect snow issues will confine
themselves to mainly just ksyr-krme by mid morning,
unfortunately another clipper system appears likely to bring a
few to several hours of a 1 to 2 mile visibility light snow into
the region beginning 02z-05z Thursday yet wrapping prior to 12z
for most if not all terminals. Winds will also slacken this
evening while backing west-southwesterly.

Outlook...

Thursday through Thursday Night...Lake effect snow will
probably again visiting ksyr-krme; mainly VFR elsewhere.

Thursday night through Sunday...still multiple chances for snow
showers/intermittent restrictions, from weak passing systems.

&&

Bgm watches/warnings/advisories...
PA...none.
New York...Winter Weather Advisory until 6 PM EST this evening for nyz025-
046-055>057.
Winter Storm Warning until 6 PM EST this evening for nyz009-
016>018-036-037-044-045.

&&

$$

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