Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 041145
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
645 AM EST Sun Dec 4 2016

.SYNOPSIS...
After a quiet and dry day, a system will bring a quick light
coating of snow tonight into early Monday. This may make roads
slick for the Monday morning rush hour. Unsettled weather will
continue through midweek with chances for both rain and snow. A
shot of arctic air will arrive late in the week including
potential for lake effect snow.

&&

.NEAR TERM /THROUGH MONDAY/...
350 AM Update...
Main concern this period will be a quick coating of snow tonight
into early Monday, which could cause a slick morning commute.

For now, drier air is working its way into the area, though a
thin layer of moisture remains trapped under a subsidence
inversion as brief high pressure moves into the region. The high
early this morning is just to our west, and thus light northwest
flow continues to provide lake moisture for those clouds. They
will only gradually mix out during the day as the high moves
directly overhead, with clouds lingering longest as usual in
Central New York. Those that manage to get a window of partial
sunshine better enjoy it while they can, because high clouds will
already start streaming in this afternoon ahead of the next
system; thickening towards sunset. Despite warm air advection
aloft, a stable profile with chilly air - underneath clouds much
of the time - will prevent temperatures from getting out of the
30s for most of the area. The Wyoming and Delaware valleys of
Northeast PA-Sullivan County NY stand the best chance of eclipsing
40 degrees.

Confidence is high that snow will break out tonight in response to
good yet brief isentropic lift of deep moisture including and
through the dendritic growth layer aloft (10-16 thousand feet up
where temperatures will be in the Teens below zero Celsius). This
system will be a clipper of sorts, with an initial warm air
advection wing arriving this evening which will cause top-down
moistening of the atmosphere. Right on the heels of that will be
an occlusion aloft, during which if snow is not already reaching
the ground before that, it will once that feature arrives. Model
blended precipitation yields a widespread one to two tenths of an
inch liquid-equivalent overnight into early Monday, with perhaps
closer to a quarter inch in some parts of Central New York.

Employing 15:1 snow-to-liquid ratios and trending down towards
10:1 with time, not much has changed from the previous forecast
for snowfall except that prospects for topographic lift in
northern Oneida County has compelled me to trend higher there into
a 2 to 3 inches range. The same can be said for the highest
Catskill elevations of Northern Sullivan- Southeast Delaware
Counties. For most areas 1 to 2 inches total still looks good for
tonight through Monday morning. In addition to the exceptions
mentioned above, the I-88 corridor toward the higher terrain
between Binghamton-Albany, and also the higher terrain between
Binghamton and Syracuse-Utica stand a better chance of around or
slightly above 2 inches. The least amount of snow looks to be in
the Wilkes-Barre/Scranton area with up to an inch in the higher
elevations just outside the valley, but generally under an inch in
the metro areas themselves. So again, the amounts are not
overwhelming but the timing is not optimal for the Monday morning
commute as roads could be slippery.

The light snow will gradually lift northeast Monday morning,
allowing a dry slot to overtake the region during the day and only
spotty lingering mixed rain-snow showers. Highs will actually
still manage to get upper 30s-lower 40s which will cause much of
the newly fallen snow to be short-lived from afternoon melting.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Transient high pressure builds in briefly for Monday night with partial
clearing, light winds, and lows generally in the upper 20s to low
30s.

Heading into Tuesday, the next system will move NE toward the
area. Overall set up will be deep trough over the central/western
CONUS with a low pressure system on the eastern side of this
feature lifting NE from the Gulf coast region toward the Ohio
Valley during the day Tuesday. Some sun early in the day will give
way to skies quickly becoming mostly cloudy with precipitation
breaking out SW to NE during the afternoon. Precipitation type
still looks to be tricky. Daytime highs will reach the upper 30s
with temps aloft initially below freezing. For this reason, rain
or a rain/snow mix initially will likely trend more toward mostly
snow by the early evening for much of the region. However after
this time some differences in the models regarding the exact
evolution of the low and how much warmer air as able to make it
into the region. In the bigger picture, primary low will move NE
toward western PA with a secondary low developing off the
Delmarva. GFS keeps primary low a little stronger than most of the
other models resulting in warmer air advecting in with a change to
rain. NAM is cooler and keeps mainly snow going across much of the
region through the evening before a mix or change to rain or even
a little freezing rain would be possible overnight. Considering
the remaining uncertainty, continued to utilize a model blend
approach and keep a mix of rain and snow in for most of the
forecast area Tuesday night. The best chances for seeing mainly
snow with a few inches of accumulation possible would be the
higher terrain areas of the western Catskills. `

The low will be a quick mover with rain/snow moving out west to
east during the first part of the day Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
400 AM Update...No major changes to long range forecast. Still
uncertainty regarding a potential system Thursday with colder
temps to follow for the end of the week into next weekend.

300 PM Saturday Update... Our next focus in our active pattern
will be the potential for more rain and snow Thursday, along with
much colder air arriving Thursday night into Friday. By Friday we
should be into the heart of the cold air with 850 temps into the
teens below zero. This should be more than enough with a west-
northwest wind for lake snows downwind of Lake Ontario. In general
used a model blend which kept chances for precip in the 30 to 50%
range, but I did increase chances by Thursday night into Friday
downwind of the lakes given the impending colder surge of air.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Though a thin layer of lake moisture remains trapped under a
subsidence inversion, ceilings have lifted into VFR for KAVP-KSYR-
KRME-KELM. KBGM-KITH will still be bouncing in and out of a high
end MVFR ceiling this morning. All terminals will achieve VFR late
morning through early evening as the lower clouds scatter.
However high thin VFR clouds will begin to develop ahead of our
next system, then lowering and thickening this evening. High
confidence in light snow and associated MVFR to IFR VIS
restrictions spreading west to east across the terminals 04Z-08Z
Monday. Ceilings should also lower to at least fuel alternate. Northwest
winds 4-8 knots early this morning, will become light and
variable during the day and then light southeast for tonight.

OUTLOOK...
Monday...Restrictions likely Monday morning as light snow finishes
lifting out of the region, especially KSYR-KRME. MVFR CIGS could
linger for some terminals after the snow ends, along with spotty
rain or snow showers in Central NY.

Monday Night-Early Tuesday...Mainly VFR.

Tuesday Afternoon-Thursday...Restrictions in wintry mix or rain.

&&

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

&&

$$
SYNOPSIS...MDP
NEAR TERM...MDP
SHORT TERM...PCF
LONG TERM...Heden/PCF
AVIATION...MDP



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