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Area forecast discussion
National Weather Service Binghamton New York
958 PM EST Sat Dec 14 2019

Synopsis...
a strong cyclone passing over New York and PA will keep rain over our
area late today, then usher in sharply colder temperatures and
snow tonight. Another winter storm will bring a wintry mix to
the area Monday afternoon into Tuesday.

&&

Near term /through Sunday night/...
10 PM update...
received a few reports of drizzle and freezing drizzle...and
model soundings are indicating a loss of ice crystals aloft as
the drier air above -10c moves in...which would promote more
super cooled water droplets, and subsequent fzdz at the surface
where temps are sub freezing, and drizzle where temps are above
freezing. Will carry this patchy dz/fzdz through the overnight
hours in isolated pockets of the srn tier and into the Catskills
and NE PA.

830 PM update...
only minor changes made to the forecast this evening.
Transitioned the rain to snow a bit quicker in the forecast, and
dropped forecast temperatures tonight a few degrees. Still
maintaining the 1-3 inches..mainly in the higher terrain of the
southern Finger Lakes and the hills south of Syracuse...tonight,
with the higher amounts into nrn Oneida County. Have seen
around 1 inch in nrn Oneida so far...and additional 2 to 6 is
possible through tonight and the morning tomorrow.

The rest of the forecast looks on track.

230 PM update...

Forecast in good shape. Little change.

Steady rain has moved into the area along with a strong surface
low. Aloft is a sharp progressive upper level trough. Colder air
is already moving into western New York changing the rain to snow.
This will be our weather this evening as the surface low and
trough lift northeast into Quebec. This evening winds will
increase to 10 to 20 mph with gusts over 30 ushering in much
colder air. Rain will change to snow the rest of today from
northwest to southeast and from high elevation to valleys. The
higher terrain in The Finger lakes to upper Susquehanna to Tug
Hill will get 1 to 4 inches tonight. Steady snow ends by sunrise
but lake effect snow remains mostly along and north of the
thruway for Sunday into Sunday Night. Lake effect snow amounts
will be light with 1 to 3 for the tug and less elsewhere. A
Winter Weather Advisory continues for northern Oneida County for
the combination of synoptic and lake effect snow tonight into
Sunday. The lake effect snow slowly tapers off Sunday afternoon
and night across our far north.

Fortunate that the liquid storm amounts of up to an inch will
not be all rain. Only minor river responses so far. A few of the
headwaters could get to caution stage Sunday. Snowpack will not
attribute much additional runoff to worry about this event.

Temperatures in the 40s now will drop into the low and mid 30s
this evening then remain there into Sunday morning. Highs Sunday
only a few degrees warmer. Making it feel colder will be the
wind. Strong winds will continue through the day Sunday. Some of
higher ridgetops and Catskill peaks will be blowing at 25 to 30
mph with gusts over 40 mph. This will not be widespread so no
Wind Advisory.

Sunday night low in the upper teens to lower 20s. There is a
small chance that overrunning snow could get into nepa by
sunrise.

&&

Short term /Monday through Tuesday night/...
low pressure developing over the Ohio Valley begins to head
northeast towards the area Monday evening into Tuesday, touching
off light snow across the area by late Monday morning before a
trust of warmer, more moist air brings in better lift and
increases chances for snow across the area from south to north.
GFS and Euro continue to agree on a more southerly track of this
system, with the center of the low moving first into southwest
PA, then generally heading towards Long Island and finally
quickly pushing off the coast. Meanwhile, the NAM takes this
system a little more northward into eastern New York state, with a
more pronounced warm nose nudging into the southern tier Tuesday
morning. The cooler, more southerly track continues to seem like
a more reasonable solution, as a cold Canadian high over Quebec
should continue to funnel in colder air into Monday night.

Therefore, with this latest update, the snow/mix line has been
moved more southward. Cold air in place will allow for
precipitation to start off entirely as snow across our area
before 0z, quickly changing over to a mix of rain, snow, and
freezing rain in northeast PA. The freezing line continues to
push northward through midnight, finally resting somewhere
around the twin tiers into Tuesday morning. However, there is
the aforementioned disagreement among the models, with 850 mb
temperatures staying near and below 0c according to the GFS,
Euro, and ensembles, and the latest NAM bringing above-freezing
temperatures more northward. At this time, mainly snow is
expected northeast of a line from Cooperstown to Cortland to
Hornell, with a mix of freezing rain, snow, and sleet through to
the twin tiers. A change over to mainly rain is expected into NE
PA, especially across the river valleys, as temperatures there
climb into the upper 30s and low 40s.

Tuesday afternoon, a change back over to snow is expected as the
system moves offshore, and the cold front pushes through. A dry
slot works in, shutting off snow for most of our area by 0z,
with just a few lingering showers across our eastern zones and a
change over to lake effect snow showers downwind of Ontario into
the evening.

Several inches of snow would be expected area-wide - with up to
1 to 3 inches across northeast PA and generally 3 to 4 inches
across central New York. Lesser totals would be expected in the river
valleys, where mainly rain will be seen during the day Tuesday.
A glaze of ice will be possible across much of our area,
southeast of the Cooperstown-Cortland-Hornell line.



Otherwise, we're still looking at non-diurnal temperatures
through the short term period. Temperatures starting in the 20s
Monday morning will climb generally into the low/mid 30s by the
afternoon, and won't budge much after sunset as warm air starts
moving in. Temperatures increase a couple degrees later Tuesday
morning and into the early afternoon ahead of the front, then
quickly fall back into the low/mid 20s early Wednesday.

&&

Long term /Wednesday through Saturday/...
no major changes to the extended; still looking cold with snow
showers mid to late week...then drying out and moderating some
by next Saturday.

Wednesday and thursday: a piece of Arctic air moves into the
region as an upper level low swings across the region. Very cold
air mass and unsettled conditions are expected with numerous
snow showers for Our Lake snow effect areas and flurries or
scattered snow showers further south. Highs will struggle to get
into the 20's with overnight lows in the single digits north
and teens for NE PA. If the operational GFS and European model (ecmwf) are to be
believed temperatures will have to be adjusted even further
downward given the modeled boundary layer temperatures.

Friday and saturday: the cold upper level low moves east, with
ridging, both aloft and at the surface moving in from the west.
This should bring the lake effect snow showers to a gradual end
and we should see a gradual moderating trend. Friday will likely
still be below average, with highs in the mid-20s to lower 30s,
and overnight lows Friday night still cold, in the teens to low
20s. By Saturday, early indications are for dry weather and near
to slightly above average temperatures. Highs look to reach the
mid to upper 30s for most areas.

&&

Aviation /02z Sunday through Thursday/...
rain changing to snow will bring widespread IFR conditions this
evening, especially in the central New York terminals.
Conditions gradually improve first to fuel alternate, then to
MVFR, and eventually VFR. The timing of these improvements vary
depending on location. Kavp will be the first to improve, likely
becoming MVFR by 05z and VFR by 09z. Improvements thereafter
will occur from south to north throughout the day on Sunday,
with ksyr and krme likely not seeing improvements to MVFR until
19z/20z. Lake effect snow showers may bring additional
restrictions to krme and ksyr during the day on Sunday.

Winds will be mainly westerly and on the breezy side, with
sustained winds of 15-25 knots and gusts 25-35 knots.



Outlook...
Sunday night and Monday...VFR with winds decreasing.

Monday night and Tuesday...MVFR/IFR restrictions with a wintry
mix.

Wednesday...MVFR/IFR restrictions in cny maybe reaching avp.

Thursday...VFR.

&&

Bgm watches/warnings/advisories...
PA...none.
New York...Winter Weather Advisory until 1 PM EST Sunday for nyz009.

&&

$$
Synopsis...tac

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