Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 050151
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
851 PM EST Sun Dec 4 2016

.SYNOPSIS...
A quick moving low will track through the area tonight and Monday
morning producing a couple inches of snow across central New York
and northeast Pennsylvania. Another wintry mix is expected Tuesday
night and Wednesday, before an arctic blast of air arrives late
Thursday into the weekend. Accumulating lake effect snow is likely
later this week.

&&

.NEAR TERM /THROUGH MONDAY/...
850 PM EDT Update...
Overall, the previous forecast is in good shape. Have made minor
adjustments to the previous forecast with temps. Virga is
currently moving into our CWA. The precip reaching the ground
with this system is still well off to the west. Expect snow to
start to move into our area around midnight/1AM. This system still
appears to be moving pretty quickly and expect to be out of the
area by mid-morning. Overall, forecast is in great shape. For
more information, please read the previous forecast discussion
below.


315 PM Update...

Area of focus in the near term is centered around
the light accumulating snow expected tonight and Monday morning
across much of the region.

Upper level ridge axis and weak surface high in place across central
NY and ne PA this afternoon...keeping weather conditions dry with
mostly sunny to partly cloudy skies. Even with the amount of sun
today, the low sun angle and lingering cold air mass have kept
temperatures in the 30s and lower 40s.

A negatively tilted upper trough currently over the Upper Midwest
will rotate ewd across the Great Lakes this evening and act to
develop and strengthen a surface low over the mid MS Valley/Ohio
Valley region. As the upper trough pivots ewd an area of weak mid
level waa will develop out ahead of the low and allow an area of
precipitation to form on an e-w oriented warm front. A transient
area of deep layer moisture aligned with the waa, ahead of the
trough will provide the moisture for around a quarter of an inch of
qpf. The strong upper level forcing combined with PWATs around 0.5
inch...sub freezing temperatures through the column and a narrow
corridor of steep lapse rates/strong lift in the DGZ should be
enough to trigger a broad band/area of moderate to heavy snow later
tonight and early Monday morning across much of the region. The
broad band will likely move in from the sw across n-central PA and
the central srn tier of NY around or just after midnight...shifting
to the e/ne at a fairly good clip. The heaviest snow is expect
between 3 and 7 am. Will likely see brief periods of heavy snow with
rates between 0.5 and 1 inch per hour. Total snowfall amounts are
expected to be generally less than 3 inches, with most areas seeing
a quick 1 to 2 as the band moves through. The highest amounts will
be in the higher elevations where strong winds within the boundary
layer will enhance the forcing and snow production.

The amount of snow that is left on the ground will also depend on
what happens behind the snow band that exits to the ne later Monday
morning. Model soundings are indicating a quick loss of moisture in
the mid and upper level, along with a slow warming into the mid 30s.
The loss of ice crystals aloft may lead to the potential for light
freezing drizzle early Monday morning with sfc temps below freezing,
or allow the snow to change over and/or mix with rain/drizzle
through the rest of the morning as sfc temps warm. The addition of
liquid to the precipitation will make the surface conditions rather
slushy and negate the snow on the ground.

Conditions dry out into the late morning and early afternoon hours
Monday as weak high pressure builds in and more significant drying
occurs aloft. Additional warm air advection and mixing may help
break up the cloud cover and help temperatures warm into the upper
30s and lower 40s. Winds will also increase behind the system for a
brief period of time...sustained winds Monday afternoon around 10 to
15 mph, and gusts to 25 mph...making it feel cooler than the 40s

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
320 PM Update...

A snow shower may linger early Monday evening up across northern
Oneida County otherwise a brief window of drier weather is
expected Monday night through midday Tuesday, as high pressure
builds over our area. Our next system which is now just a
meandering wave over Mexico will wait for our system tonight to
move east, then it will race rapidly northeast Monday night into
Tuesday. All 12Z model guidance has slowed the onset of the
precipitation Tuesday afternoon with the Euro/Canadian/GFS all dry
in our area through 18Z. In reality though the models are just
tightening up the front end of things as we still have
precipitation rapidly increasing over our area between 18Z Tuesday
and 0Z Wednesday. At the start precipitation should be a rain or
rain/snow mix but it should go over to mostly snow through early
evening due to evaporational cooling.

Tuesday night widespread precipitation is expected across our
area especially the first half of the night. Thermal profiles
still differ with the NAM and Euro cooler, keeping it mostly all
snow, while the GFS is warmer. A closer look at soundings shows an
isothermal profile once we saturate the low and mid levels, so it
will be a close call rain vs. snow right up through the event
itself. For our forecast I went with a mainly snow forecast for
the first half of Tuesday night, but with such a close sounding I
continued to keep it a rain/snow mix in the metro areas as surface
temps here may be 33 - 36. Gradually as the precipitation
diminishes in intensity I show a larger area of rain/snow mix
overnight through daybreak Wednesday. With such a close sounding
for rain or snow, elevation is likely to play a huge role.
Snowfall amounts now range from nothing to a light coating in the
metro areas (Syracuse/Wilkes- Barre), to 1" to 3" with the amounts
increasing based on elevation. The timing again prior to the AM
commute Wednesday may create problems, especially in the hills.


A punch of drier air from the southwest will move in by 12Z
Wednesday with a rapid end to the precipitation from west to
east. So while lingering rain or snow is possible northeast of
Binghamton just after daybreak, drier weather is likely by late
morning. Surface temps Wednesday afternoon will flirt with 40 so
any morning road issues will no longer be a concern for the drive
home.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
330 PM update...

Turning much colder is still the main weather story at the end of
this week along with significant lake snows possible downwind of
Lake Ontario. The only questionable day would be Thursday with
regards to the models. Both the GFS and EURO show a wave moving up
along our cold front Thursday which would bring a general light
snow to the area. The canadian is too strong with our push of cold
air and shows no signs of any system moving up along the front. We
will continue with continuity and the GFS/EURO by showing a
period of light snow Thursday. Beyond looks very cold with highs
for a few days only in the 20s and lows in the teens (being
modified by the lakes and clouds). Lake snows look most likely
Thursday night through early Saturday, before gradually relaxing
late in the weekend. A bit early to be too specific but with a
west-northwest flow, Central NY likely to have significant impacts.
In addition to the moderate to extreme instability over the
lakes, both the EURO and GFS show 1000-850 MB moisture above 80%
Thursday night through Friday. Sometimes with extreme cold comes
very dry air and lake effect snow is not as productive as one
would think. This type of flow, extreme instability, and wind
flow would suggest significant snows over Central NY, and snow
flurries/squalls down into northern PA.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
A low pressure system will move across the region quickly tonight
which will create snow showers across all taf sites. This system
will produce below alternate minimum visibilities at all sites
late tonight/early MON morning as -SN is the dominate forecast
precip type. This system will draw in warm air quickly and start
to transition -SN into -RASN by mid morning Monday. Flight
conditions are expected to slowly improve to Fuel alternate by
18Z, then to MVFR by late afternoon. KAVP, KBGM, KELM, and KITH
are expected to improve to VFR by 00Z Tuesday as this system will
quickly moves out of the area.

Winds will start out as light and variable early this evening,
then become breezy from the south as a warm front moves through
the region. Winds will be around 6 to 12 knots, with gusts up to
20, then become westerly tomorrow afternoon 10-15 knots as a cold
front move across the region.

OUTLOOK...
Monday Night-Early Tuesday...Mainly VFR with patchy IFR
conditions in -DZ/FZDZ at KSYR and KRME.

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

Friday...Lake effect snow showers causing restrictions through
most of the day...especially at KRME, KSYR, KITH and possibly
KBGM.

&&

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

&&

$$
SYNOPSIS...BJT/KAH
NEAR TERM...BJT/KAH
SHORT TERM...Heden
LONG TERM...Heden
AVIATION...BJT/KAH


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