Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 150015
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
715 PM EST Thu Dec 14 2017

.SYNOPSIS...
Outside of some weak lake effect snow bands, near and north of
Syracuse, tonight will be dry and cold, across central New York
and northeast Pennsylvania. Another fast moving, clipper type
storm, will bring some light snow showers and flurries from
later Friday into the weekend. A round of lake effect snow is
also possible, mostly north of the Thruway, early Saturday.

&&

.NEAR TERM /THROUGH FRIDAY/...

715 PM update...
The combination of mainly clear skies and a fresh snow pack will
allow temperatures to fall off a little quicker than originally
thought. With a few readings already in the single digits, we
lowered overnight minimums by a few degress, mainly based on the
latest ConsShort grids.

230 pm update... Backing low-level winds have shifted narrow
lake-effect snow bands northward this afternoon. We think these
snow bands will impact northern Onondaga, northern Madison, and
Oneida counties through evening. An increasingly less favorable
environment (decreasing moisture and increasing directional
shear) will keep the bands weak, with additional accumulations
mostly under an inch.

Across the rest of the forecast area (NY`s southern tier and
NEPA), it will be partly cloudy and cold, with mostly thin,
higher level clouds overhead. Lows by daybreak will range from
the single digits to near 15.

Although most of Friday looks dry (weak lake-effect bands
lifting further north and out of the forecast area), we could
see some lighter snow showers and flurries later in the day,
well in advance of our next clipper, which will be tracking
across the northern Great Lakes region. Highs Friday afternoon
will range in the 20s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
230 pm update... The aforementioned clipper is progged to track
across southern Ontario and Quebec Friday night, and into
northern New England and the Canadian maritime provinces by
Saturday. As it does so, light and patchy warm advection driven
precipitation much of Friday night, will only amount to
scattered snow showers and flurries in CNY/NEPA.

However, as the flow veers into a more westerly orientation
towards daybreak Saturday, and a low-level surface trough also
approaches from the north, dynamic support will increase for a
W-E oriented Lake Ontario snow band, which could become fairly
intense for a brief time early Saturday. At this time, although model
consensus keeps the brunt of the snow with this band just north
of Oneida county (across Oswego and southern Lewis), it may be
a close call. For now, we`ll mention potential for a period of
lake-effect snow across northern Oneida in our hazardous weather
outlook.

During the day Saturday, as the previously mentioned surface
trough drops southward across CNY/NEPA, it will carry some snow
showers with it. However, early indications are that these snow
showers will lose their punch with southward extent, keeping any
accumulations on the light side. Temperatures on Saturday will
moderate a bit ahead of the trough, with afternoon highs
ranging from the mid 20s-lower 30s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
300 PM Update...Not alot of changes to the extended forecast
period. After some lingering snow showers Saturday night into
early Sunday AM, much of Sunday should be dry but mostly cloudy.
Did bump up PoPs into the 40-50 percent chance range areawide
for a period of light snow Sunday night, as the 12z ECMWF/CMC
are in agreement that a weakening wave will track up the Ohio
Valley and into our area, bringing a period of light warm air
advection precip...the 12z GFS weakens the wave faster, and it
never quite makes it to CNY/NE PA.

Monday and Tuesday will feature a moderation of temperatures
as the area remains under a mild southwest flow, with highs
reaching 35-45 both Monday and Tuesday. Weak waves will move
through, bringing chances for rain and higher elevation snow
showers. Models are still in good agreement that a rather strong
cold front will push through the area Tuesday night...dropping
850mb temperatures back down to around minus 10-12C. This
colder air-mass will combined with a moist northwest flow regime
to bring renewed chances for lake effect snow and snow showers.
There is the potential for some significant snow accumulations
in the favored lake effect areas of Central NY.

The model guidances then begins to struggle/diverge heading into
the end of next week as a deep low pressure system and
associated warm front move toward the region. Precipitation
type, amounts, and overall temperatures are very uncertain for
this period. These will strongly depend on the ultimate track
of the surface low and frontal position. The 12z GFS actually
pushes the low further south as it runs into a very cold air
mass in southern Canada...meanwhile the 12z ECMWF and CMC allow
the low to strength and move well to our west, through the Great
Lakes. This type of track would place our CWA in the warm sector
of the storm system, with much higher temperatures. With all of
the uncertainty in this period, decided to make only very minor
changes...mainly to slightly raise temperatures and PoPs.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Lake effect band giving local IFR conditions to RME will end in
the next few hours. Otherwise, VFR conditions will prevail
through the TAF period. Winds will generally be light. Next
system expected to bring snow and lower conditions will arrive
beyond this TAF period.

Outlook...

Friday night and Saturday...Periodic restrictions possible in
snow showers, especially KSYR and KRME.

Sunday...VFR.

Monday and Tuesday...Possible restrictions in rain or snow
showers.

&&

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

&&

$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...MJM/RRM
AVIATION...DGM/MLJ



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