Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 080930

Area Forecast Discussion
National Weather Service Binghamton NY
430 AM EST Thu Dec 8 2016

Brief snow squalls are likely across central New York this
afternoon and evening with up to two inches of snowfall possible.
More organized and persistent lake effect snows will develop
southeast of Lake Ontario overnight and continue into Saturday


An upper level trough over the central Great Lakes will approach
the region today resulting in a deep southwest flow into the
region. Continued weak low level cold air advection will continue
today and bring lake effect snow showers from Lake Erie into
central New York primarily this afternoon and evening. Model
soundings indicate steep low level lapse rates which will
intensify the activity into brief snow squalls. Snow accumulation
up to two inches is possible especially in the higher terrain.

The lake effect snow band off Lake Ontario will remain primarily
north of northern Oneida County through this afternoon. For this
reason the warning for northern Oneida County has been changed to
4 PM.


Lake effect snow warning is now in effect for northern Oneida
county from 4PM today to 7AM Friday. Lake effect snow advisories
are in effect for Onondaga, southern Cayuga, southern Oneida,
Madison, Cortland, Chenango, and Otsego Counties from 10PM this
evening to 7AM Saturday.

A significant band of lake effect snow will drop into northern
Oneida county early this evening. A flow around 270/275 degrees
will persist through 09Z with inversion height near 750mb along
with favorable snow growth potential and moderate instability.
Snowfall rates of 1 to 2 inches per hour are likely with total
snow accumulations of 6 to 12 inches. After 09Z, a secondary
trough will drop the lake effect snow band south into the advisory
area. Once this boundary drops south the inversion lowers and the
moisture depth becomes more shallow implying less snow growth
potential therefore smaller dendrites. Temperatures at 850mb
continue to drop to around -15C so with lake temperature near 9C
the instability is extreme. This flow will persist through Friday
night at roughly 300 degrees so persistent flow and cold airmass
are the favorable conditions for significant lake accumulations.
Lowering inversion height and shallow moisture are the limiting
factors. Based on the persistent flow decided to issue a long
duration lake effect snow advisory for the area with 4 to 8 inches
likely. The higher accumulations will occur in the higher terrain
in southern Onondaga, southern Madison, northern Cortland and northern
Chenango counties.


340 AM Update... Low level flow will back slightly on Saturday,
which will be enough to carry some Lake Erie snow showers into the
Twin Tiers while also guiding Lake Ontario back along and then north
of the Thruway into Saturday evening. Wind will be fairly light and
moisture limited, so snow accumulations will generally be less than
an inch.

Brisk flow aloft will send another shortwave through the area
Sunday. There is some uncertainty as to whether enough moisture will
exist for snow to occur, thus the chances are in the 30-50 percent
range. However the thermal profile of the atmosphere at that time
will include a thick portion at dendritic growth temperatures. Thus,
it will not take much moisture and lift combination to yield at
least a little light snow.

Pattern remains stormier than normal. A low pressure system will
track across the region Monday, either through the Ohio Valley which
would mean snow as per GFS, or through the eastern Great Lakes which
allow some rain to mix in as well as per ECMWF and GEM. The models
agree on very cold Arctic air arriving during the second half of the
week but disagree on how messy that transition is during midweek. It
will likely include yet another system but the magnitude of it
is uncertain.


Though the sky will be usually broken or overcast, generally VFR
conditions are expected this TAF period except during lake effect
snow showers for KSYR-KRME-KITH-KBGM. Due to the amount of dry air
initially, confidence has decreased for Lake Erie snow showers
reaching over to KSYR-KRME 12Z-16Z and thus these have been
removed from the TAFs. However, KITH and KBGM still do stand a
decent chance of Lake Erie snow showers passing through this
afternoon with VIS reducing to at least IFR. The chance is less at
KELM so not in TAF, but brief restrictions will be possible.
Then, there is good confidence that around 03Z- 06Z Friday, a
squally Lake Ontario band will drop through KSYR-KRME. IFR VIS
has been put into the TAFs for then, but there is some potential
for less than a mile VIS. Generally light southwest wind early
this morning will veer more westerly during the day while picking
up into 9-14 knots range with gusts approaching 20 knots.

Friday through Saturday Night...Restrictions at KSYR in lake
effect snow; possible occasional restrictions in snow showers or
flurries for KRME-KELM-KITH-KBGM. KAVP mainly VFR.

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

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


NY...Lake Effect Snow Advisory from 10 PM this evening to 7 AM EST
     Saturday for NYZ017-018-036-037-044>046.
     Lake Effect Snow Warning from 4 PM this afternoon to 7 AM EST
     Friday for NYZ009.


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