Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 022353
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
653 PM EST Fri Dec 2 2016

.SYNOPSIS...
Cold upper low over eastern Canada will allow rain and snow showers
to persist through late Saturday night, especially in Central New
York. After a quiet Sunday, a passing disturbance Sunday night
may produce a brief light snow, followed by spotty mixed rain and
snow showers Monday. A larger system may affect the area toward
the middle of next week with mixed precipitation changing to rain.

&&

.NEAR TERM /THROUGH SATURDAY/...
745 PM Update...
Lake effect band first impacted Northern Oneida County and is now
dropping down to the NY Thruway. Radar observations and
webcams/NY Mesonet sites show that up to a quick inch of wet snow
is occurring at the higher elevation sites, whereas lower
elevations start as mainly rain and then a mix of rain-snow with
very little if any accumulation. There was just even a recent
lightning detection within the band in Oswego County. This is
occurring in tandem with a passing shortwave aloft, behind which
flow will veer more northwesterly and thus the lake band as per
latest higher res models will lose intensity while becoming more
narrow multi-band in nature and focus more on Cortland- Norwich
areas overnight instead of Syracuse-Utica areas which are getting
impacted during the next couple of hours. Forecast adjusted for
these finer details but not much change to the overall situation.

Previous discussion...
Radars show fairly widespread rain showers (mixed with snow
higher terrain) across north central NY and another batch of rain
and mixed rain/snow showers across the southern tier. This
activity was developing in a moist westerly flow of air ahead of
an upper level short wave that was dropping southward across the
eastern lakes. We have scattered to widespread rain showers mixed
snow showers higher terrain this afternoon in grids. Then for
tonight with a colder more northwest flow and plenty of low-level
moisture behind the upper level wave, we see more snow showers
downwind of Lake Ontario. The snow will mix with rain in our lower
terrain. These snow showers will last into Saturday as the low-
level flow remains around 315-325 degrees. The inversion is
expected to drop from 780 mb tonight to below 800 mb by Saturday
morning. The maximum CAPE and omega is below the temperatures for
the maximum growth of ice crystals so we are not expecting higher
snow ratios. Also boundary layer temperatures will be marginal
through Saturday, especially lower terrain. End result is that the
central NY highlands likely will see 2-3 inches of snow with
locally 4-5 inches. The higher terrain of northern Oneida County
also could see a few inches with the lower elevations seeing
little to no snow area-wide and moderate elevations (1300-1600
feet or so) maybe an inch or so by Saturday evening. Otherwise it
will be cloudy and gradually turning colder through the period.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Main concerns in the short term remain focused around the continuing
lake effect showers Saturday night and Sunday morning...and the next
system sliding through Sunday night and Monday.

Northwest flow off Lake Ontario and 850mb temps -7 to -9 deg C will
continue to produce light lake effect snow showers Sat night and
early Sun morning. Some of the snow may mix with light rain or
drizzle in the lower elevations of the Finger Lakes where sfc temps
will be slightly warmer. Snow amounts during this time will only be
trace amts or up to a half inch at most.

Weak high pressure at the surface and ridging aloft build in behind
the departing system which will act to end the snow showers and
bring a brief period of dry weather Sun afternoon and evening. Some
areas may see a brief peek of sun during this time, mainly the srn
tier of NY and ne PA. Otherwise, the next system begins to push in a
layer of high clouds from the sw Sunday night with light snow
beginning across the central srn tier and lifting to the north
across most of the forecast area Monday morning. A weak upper trough
and associated area of weak warm air advection aloft will provide
the lift necessary for a broad area of light snow...possibly
changing to a rain/snow mix in the lower elevations late Monday
morning and into the afternoon. Temperatures aloft will likely stay
below freezing...which will help most areas see a quick slushy 1-2
inches of snow.

Temperatures will remain on the cool side but near average for this
time of year with highs in the upper 30s near 40 and lows in the 20s
and lower 30s.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Weak high pressure builds in at the surface behind the departing
wave to the northeast as ridging aloft amplifies over the wrn Great
Lakes ahead of the next s/w expected to move in from the sw
again...but slowly phase with a much colder and deeper trough
digging into the Upper Midwest/Great Lakes early Wed. The broad
large scale lift and strong dynamics aloft will work with the much
colder temperatures in the mid levels and steep low level lapse
rates to produce showers across the region. There is still some
uncertainty with regard to the thermal profiles...which will prove
important in deciding p-type. Will go with mainly a rain/snow mix
during this time...but lean more toward the cooler, snow solution.
Snow and/or rain amounts should be relatively light through
Thursday as the air mass will be lacking any significant deep
layer moisture. There may be a lake component involved too...which
will again depend on the thermal profiles and if the real arctic
type air mass moves in quicker than expected at this point.

Highs will remain steady in the upper 30s and lower 40s...with
overnight lows in the 20s and 30s.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Passing disturbance aloft will cause shifting lake effect rain-
snow showers across the NY terminals this evening for KSYR-KRME
then overnight at times for KITH-KBGM accompanied by ceilings to
fuel alternate required at times. Winds will also veer ever so
slightly more northwesterly behind the disturbance 10-15 knots
with gusts roughly to 20 knots. Moist and chilly northwest flow
continues through Saturday with KELM-KAVP and eventually KSYR-KRME
improving to VFR yet KITH-KBGM persisting at MVFR CIG with spotty
lake effect snow showers.

OUTLOOK...

Saturday Night-Early Sunday...Restrictions at times KSYR-KITH-
KBGM due to occasional lake effect snow showers.

Sunday Midmorning through Evening...Mainly VFR.

Sunday Night-Monday...Restrictions possible as weak system brings
light snow Sunday night, then spotty rain-snow Monday.

Monday Night-Early Tuesday...Mainly VFR.

Tuesday Afternoon-Wednesday...Restrictions in mix or rain.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.

&&

$$
SYNOPSIS...DJN/MDP
NEAR TERM...DJN/MDP
SHORT TERM...BJT
LONG TERM...BJT
AVIATION...MDP



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