Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 072335
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
635 PM EST Wed Dec 7 2016

.SYNOPSIS...
Lake effect snow showers will develop over NY and far northern PA
on Thursday, and become more potent heading into the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
205 PM update...
A potent polar air mass will plunge into the base of a trough
rotating through the northeastern U.S., activating the lakes early
Thursday.

We largely followed the lake bands produced by the CMC Regional
guidance, as these look realistic in terms of placement and QPF.
However, we added in a larger area of light snow surrounding the
bands over central NY, as persistent northwest flow should
generate light precipitation nearly to the NY/PA border by mid-
afternoon.

Most NY sites will not make it out of the 20s on Thursday.

1030 AM update...
With precipitation moving out and clouds thinning, temperatures
are climbing quickly this morning, with several observations
already at or above the projected maximums.

We raised forecast maximums this afternoon.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Lake effect snow watches and the warning for Northern Onedia
county remain in place. The main change with this update was to
lower snowfall amounts as some favorable factors for high amounts
of snow are now becoming less favorable.

A lake effect band of snow north of our area Thursday evening
should impact northern Oneida County through 06Z Friday with a
flow between 270/275. Inversion heights are well above 10,000
feet, with a good fetch over lake with moderate instability. The
snow growth region is a bit lower than yesterday and the models
are still forecasting shear. This may widen the band somewhat but
also make it more diffuse. The other question mark is some models
are faster with a trof, which would shift our winds into the
northwest and sink the band farther south than currently
anticipated. We lowered amounts a bit to compensate for some of
the concerns above but overall this area remains the most likely
area to see signficant snowfall in our area, at this vantage
point.

Early Friday the trof mentioned above will swing through and
disrupt the snow band while moving it south. Eventually a steady
300 to 310 wind flow will set up Friday and Friday night. The
inversion heights do lower as expected but they are 2 to 4kft
lower than the runs of the models yesterday. In addition while not
perfect, the snow growth region is a bit higher than previously
thought and the best lift in the atmosphere may not line up as
well. Model QPFs remain very low and while not usually at all in
reality in lake effect events, with the low QPF and the slightly
less favorable conditions just 24 hours removed from yesterday, it
was hard to argue in not lowering amounts. The WATCh will remain
in place and hopefully we can have more clarity tonight with the
0Z runs. We may be looking at a widespread lake effect advisory
area vs. a warning but time will tell. Speaking of an advisory,
folks in nothern Cortland, Chenango, Delware and Otsego counties
will remain close enough to lake snows that advisory level snows
are possible here. We will mention it in the hazardous weather
outlook.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
210 PM update...

A persistent trough over the northeastern U.S. will keep the
weather stormier than normal, while temperatures remain on the
cool side. Lake effect snows will be ongoing Saturday night, with
most of the activity migrating north of Oneida County on Sunday.

A powerful storm will move up the Ohio Valley on Monday, bringing
another round of snow, possibly mixing with rain during the
warmest midday hours.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
VFR expected overnight with bkn to ovc mid to high level clouds.
The main concern will be the potential for brief heavier snow
squalls Thursday at the NY terminals. While the heaviest and
steadiest snows will remain well to the north and west of the
terminals, two time periods may poise a problem.

First between 12Z and 16Z some mvfr cigs to high end ifr vsbys
possible at KSYR and KRME in light snow showers. Not expecting
vsbys to drop below 1 to 2sm here.

After 18Z a band of lake effect snow off Lake Erie will likely be
near KITH and perhaps even KBGM. During that time at least mvfr
cigs and vsbys will be possible. Confidence was higher the band
would be closest at KITH so I included some high end ifr here. It
should be noted however that brief vsbys under 1sm are possible in
the heaviest of squalls.

OUTLOOK...
Thursday night -Saturday...Restrictions likely at KSYR in lake-
effect snow, with possible restrictions in snow showers/flurries
down to KRME, KELM, KITH, and KBGM. KAVP should be mainly VFR.

Sunday...Widespread restrictions becoming more likely with a general
light snowfall.

Monday...restrictions possible in sct. snow showers.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...Lake Effect Snow Watch from Thursday evening through late
     Friday night for NYZ017-018-036-037.
     Lake Effect Snow Warning from 11 AM Thursday to 7 AM EST
     Friday for NYZ009.

&&

$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...MLJ
LONG TERM...DJP
AVIATION...Heden


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