Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 240003

Area Forecast Discussion
National Weather Service Binghamton NY
703 PM EST Mon Jan 23 2017

A storm will track up the east coast through Tuesday.
This system will bring heavy wet snow, sleet, and freezing rain to
central New York and northern Pennsylvania. After this storm
system passes, a weaker trough moves through Wednesday with a
chance for showers. Colder temperatures follow for late week.


700 pm Update...
No significant changes made to the forecast with precip spreading
northward this evening. The leading edge of the precip...generally in the form of -RA with a mix of -FZRA/PL/SN. Still
expecting later this evening and into the overnight hours, the
precip to change over to all snow as the influx of deep moisture
continues and the column cools below freezing, making conditions
favorable for either snow or sleet.

Previous Discussion...
Very complex but significant system will impact the area tonight
through Tuesday...

Strong system beginning to impact the forecast area as northern
edge of precipitation shield is pushing into NE PA. The actual
low is still centered near the Carolinas with a strong high over
eastern Canada that is feeding colder, drier air into the storm at
the lower levels. Temperatures currently in the 30s and of
concern, temps already dropping to freezing in places in NE PA due
to dry air and wet bulb cooling.

As we head into this evening, precip shield will move north to
encompass entire CWA. Our forecast models are in overall good
agreement on the big picture of this large storm moving slowly
from the Carolinas northeast to a point east of New Jersey by Tuesday
morning. While cooler air has been filtering in in the lower
levels from the E/NE, concern continues to be warm layer aloft
which will be trying to advect in from the SE. There are small but
very important differences in the models regarding this warm layer
which will have a significant impact on precipitation types...this
continues to make this a very challenging forecast. NAM still the
warmest model while GFS is colder. Gem is in between while some
of the higher res guidance leans more toward the NAM. The
challenges in these temperature profile details will occur in
tandem with the storm spreading heavy precip in the forecast area
for the evening and overnight. Based on the consensus of guidance
and current conditions, best thinking is that roughly the southern
and eastern half of the CWA from Broome County S/E will be dealing
with significant sleet and freezing rain and even rain this
evening that may really cut down on snow amounts before precip
trends more toward mostly snow later tonight. Farther north and
west through the Finger Lakes to Steuben County then NE to the
Tughill is the area we are most concerned about for 6-8+ inches of
heavy wet snow. Even these areas may see sleet and freezing rain
this evening for a time. However, as heavy precip moves in which
will be forced both by strong upper level forcing and mid level
frontogentical forcing this should act to cool the profile in
these areas below freezing changing precip to mostly snow. Winds
gusting up to 35 mph will also be possible with the storm tonight
adding to the impacts of snow/ice...possibly resulting in downed
tree limbs and power outages in addition to dangerous travel

For Tuesday...low moves from east of New Jersey NE to near Cape
Cod by late day. Precipitation will become lighter with time but
continue through the morning before easing in the afternoon west
to east. Still expect the above mentioned areas in the eastern /
southern parts of the CWA may see some freezing rain and sleet at
times, especially in the morning. Otherwise, mostly snow in the

In terms of storm total, still expect 6-8+ inches of heavy, wet
snow over our western and northern zones (NW of Broome County).
In fact, if a frontogenically forced heavy band sets up this
evening this could result in rates of 1-2+ inches an hour and
localized storm totals of 10-12+ inches. Snow totals farther S/E
will generally be in the 2-6 inch range. Also, big change with
this update was adding in freezing rain for many areas but think
ice accretion should remain under a quarter inch. Temperatures
through the event will remain in the low to mid 30s.


300 pm Update...
Exiting low pressure just off the coast of New England and trailing
upper trough in the eastern Great Lakes will allow the snow and
possibly sleet to persist Tuesday night and early Wednesday morning.
Snow amounts should be light, as the mid/upper levels dry out
quickly with high pressure building in from the west. The overall
trend Wed morning will be drier with slightly warmer temperatures
into the upper 30s and lower 40s. The ridge will very quickly shift
to the east, but the warm air will linger a bit as a pre-frontal
trough lifts ewd through the region. This trough will act to product
scattered rain showers later in the day Wednesday and Wed night.

Thursday will be a transition day with the colder air moving in
slowly from the west. As 850mb temps drop to -2 to -4 deg C...the
rain will begin to mix with snow...especially in the higher
elevations through Thur afternoon. The mix of rain and snow will not
result in much snowfall accumulation...and only a trace to around a
couple tenths of an inch of liquid...with the highest rainfall amts
expected in central NY.


300 pm Update...
There will be a noticeable cool down Thursday night as 850mb temps
cool to -8 to -10 deg C. Surface temperatures will fall into the mid
20s. This strong push of cold air from the NW will induce weak lake
effect bands off Lake Ontario...with the primary area of
accumulating snow expected near the Thruway and north. It is still
too early to define snow amounts, but several inches are possible
through the end of the week. The air mass will become slightly
cooler...around -12 deg C later in the day Friday...which may
enhance or allow the snow band to become better defined. There is
some variation in the trajectories off the lake...but the overall
consensus is for a 280 to 290 deg flow...which will keep the snow
confined to areas to the north.

The flow backs to the w/sw late Saturday and Sunday but the cold air
mass persists. So, will likely see the lake band shift to the north
out of our forecast area, with temperatures continuing to be rather
cold...highs in the 20s and lows in the teens.


leading edge of precipitation is falling in the form of -RA mixed
with -FZRA/PL...accompanied by generally VFR ceilings. As the
precip fills in from south to north tonight ceilings are expected
to drop to MVFR/fuel alternate...with IFR/MVFR vsbys in the wintry
mix, changing to all -SN or SN/PL. Precip type remains in question
as rapid changes will be seen this evening. There is the potential
for a period of heavy snow later this evening into the overnight
across central NY sites (especially for KELM,KITH and possibly
KSYR and KBGM) which could bring visbys to less than 1 mile.
Precip in the form of SN/PL late tonight/tomorrow morning will
begin to taper off through the morning hours (12-17Z) for all
sites except KRME where IFR may persist into the afternoon.
Ceilings will likely remain MVFR or fuel alternate with flurries
into the afternoon.

Gusty east winds this evening around 15 knots gusting 20-30
knots...will diminish gradually through the overnight hours
backing to the north and nw by tomorrow.


Tuesday night...Fuel alternate or MVFR ceilings with visibility
restrictions in light snow or a mix of snow/sleet.

Wednesday...Generally VFR conditions with possible restrictions
in rain showers later in the day.

Thursday - Saturday...Restrictions possible in snow
showers...mainly at KRME and KSYR.


PA...Winter Storm Warning until 1 PM EST Tuesday for PAZ038>040-043.
     Winter Weather Advisory until 1 PM EST Tuesday for PAZ044-047-
NY...Winter Storm Warning until 1 PM EST Tuesday for NYZ009-015>018-
     Winter Weather Advisory until 1 PM EST Tuesday for NYZ062.


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