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000
FXUS61 KBGM 310135
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
935 PM EDT Fri Oct 30 2020

.SYNOPSIS...
Stray lake effect rain and snow showers give way to dry weather
late tonight and Saturday. Tonight will be the coldest night of
the season so far with lows in the teens and 20s. Showers
return later Sunday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...

935 PM update...

It will be a quiet, chilly overnight.

Clouds are lingering longer than expected this evening. With
temperatures running a few degrees above plan, we nudged
overnight temperatures toward the latest mesoscale guidance,
which is a few degrees warmer.

The forecast remains in good shape.


330 PM Update...

Much of the rain/snow activity across our area has come to an
end, but we won`t rule out any stray lake effect rain and snow
showers downwind of Ontario the rest of the day and into the
night under cold northwest flow. Chances will mainly be across
the Finger Lakes and western Twin Tiers this afternoon with
north-northwesterly flow, but as winds shift more to the
west/northwest overnight, a chance for flurries and snow showers
migrates northward towards the NY Thruway before finally
wrapping up late tonight.

Otherwise, temperatures hover in the 30s so far, but should be
able to peak in the upper 30s to lower 40s across much of the
area with some spots across the higher terrain likely only
staying in the mid 30s. High pressure building in will usher in
a cold and dry airmass. As temperatures and dewpoints fall back
and skies clear out, with increasingly lighter winds tonight,
surface temperatures will be able to turn very cold. Expect
lows in the teens to mid 20s.

High pressure starts to shift east of the area into Saturday,
with southerly return flow allowing temperatures to climb a bit
higher into the 40s under sunny skies. Overnight, southwesterly
flow strengthens ahead of a deepening trough across the Upper
Midwest. This will allow for increasing temperatures aloft and
more persistent winds throughout the night, which will help to
keep temperatures more mild than the previous night. Expect
lows in the upper 20s and lower 30s with increasing clouds.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
300 pm update...
Main concerns in the short term remain focused on the storm
system expected to track east across the Great Lakes into the
Northeast Sunday into Monday morning.

Deepening cutoff upper low over the nrn Great Lakes Sunday
morning will induce modest warm air advection ahead of the
system across PA and NY. This initial air mass will be
relatively warm with temperatures climbing into the upper 40s
and lower 50s. However, a cold front associated with this system
will pick up steam and roll into wrn NY Sunday morning. Ahead
of the front, southwest winds will increase in response to a
tightening surface pressure gradient. Winds will strengthen to
15 to 25 mph and gusts up to 35 mph Sunday morning and
afternoon. The front will push east through central NY into the
afternoon and trigger rain showers over a good portion of the
region. As much as a quarter of an inch of rain is possible,
with the highest amounts along and north of the Thruway.

The front moves through rather quickly late Sunday with a dry
slot forming and pushing in from the southwest early Monday
morning as the system wraps up. As the drier air moves in on the
back side of the system, so will the colder air. A few snow
showers will mix in at times late Sunday night before changing
to all snow by Monday morning. A stronger push of colder air
will begin to pour in Monday morning with 850mb temperatures -8
to -11 deg C...and with Lake Ontario water temperatures around
10 deg C, this will prove very favorable for lake induced
instability and subsequent lake effect snow showers. The
dominant 330 deg flow should allow for mostly multi-banded snow
down stream of Lake Ontario, with some Finger Lake enhancement
as well. There may be a window with sufficient lake to lake
connection upstream also that could enhance some of the lake
bands even further with embedded heavy snowfall rates. Will
need to keep an eye on the potential for possibly hazardous LES
for the Monday morning commute.

Temperatures will gradually warm from the 20s Monday morning
into the upper 30s and lower 40s by the afternoon. This warm up
could allow some of the lingering snow showers to change to or
mix with rain.

The other main story with this system will be the strong
northwest winds behind the front on Monday. Through most of the
day winds will be sustained out of the NW around 20 mph, with
gusts up to 35 mph at times. Blowing snow and reduced visibility
could be an issue on Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
300 pm update...
Lake effect snow showers taper off slowly Monday night, and will
likely linger into Tuesday morning as the 850mb ridge axis does
not transition through the region until Tuesday afternoon. The
air mass will slowly warm through the day with temperatures
starting out in the 20s and climbing into the upper 30s north,
to mid/upper 40s in ne PA.

By Tuesday night an upper ridge will start to build across much
of the central and eastern U.S. This feature will usher in not
only much warmer air, but also much drier air through the middle
of the week and possibly into the end of the week as well.
Temperatures warm into the 50s and 60s by Wed and Thursday.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
The cold NW flow is allowing clouds to stream off Lake Ontario
into west-central NY and PA this evening. Cloud bases are
generally between 2-5k ft agl in these lake effect/upslope
areas. Overnight, the flow is expected to back more westerly,
which should push the clouds at least slightly further east than
is currently being observed at 00z. Overall, think this should
mean some rather persistent MVFR CIGS at ITH and BGM most, if
not all of the overnight....right into Saturday morning. Expect
borderline MVFR/Low end VFR CIGS at ELM and SYR most of the
night. The borderline MVFR/ Low end VFR clouds are forecast to
reach RME late tonight or early Saturday morning for a
time...mainly 09-15z Saturday. The clouds should also reach AVP
after 06z, and continue until 12-15z Saturday...although am
expecting bases to generally remain VFR here.

Lingering clouds through 15-18z Saturday for most of the NY
terminals...likely trending to VFR bases though. Then, expect
fast clearing, with SKC conditions areawide Saturday afternoon
and evening under high pressure.

NW winds 5-10 kts this evening, becoming westerly then variable
and light overnight. Winds turn south-southwest Saturday morning
and into the afternoon 5-10 kts.

Outlook...

Saturday night through Sunday morning...Mainly VFR. LLWS
possible with a strengthening southerly flow just above ground
level.

Sunday afternoon through Monday...Frontal system moves through
with rain late Sunday, followed by occasional ceiling restrictions
and mixed snow/rain showers into Monday; mainly NY terminals.

Tuesday and Wednesday...Mainly VFR

&&

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

&&

$$
SYNOPSIS...HLC
NEAR TERM...DJP/HLC
SHORT TERM...BJT
LONG TERM...BJT
AVIATION...HLC/MJM