Area Forecast Discussion
Issued by NWS Binghamton, NY

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FXUS61 KBGM 272353
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
653 PM EST Sat Nov 27 2021

.SYNOPSIS...
A clipper system will produce a couple rounds of snow, late
tonight and again later in the day Sunday. The pattern will
remain active next week, with several weak systems bringing more
chances for light snow.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
600 pm update...
Slowed down the onset time of the light snow later this evening
by a couple hours as the latest high-res, near term model
guidance is trending slower. Otherwise, no major changes made to
the forecast at this time.

330 PM Update...

Most of the area has been able to dry out, with some breaks in the
clouds as we experience a (very) brief period of ridging. The
exception is for areas downwind of Lake Ontario. Lake effect clouds
and flurries continue to extend southeast of the lake all the way to
the western Catskills and Southern Tier. However, these continue to
wrap up into the early evening. Temperatures have stayed a couple
degrees cooler in some spots than expected, but are still hovering
in the upper 20s and lower 30s this afternoon while brisk
northwesterly winds gradually diminish.

Temperatures quickly fall back into the 20s by around 0Z, but clouds
will be working back in from the southwest ahead of an approaching
shortwave should help to keep temperatures from falling back much
further the rest of the night. A weak warm front, currently draped
over the Ohio valley, will move northward into central or perhaps
even northern PA. This should provide enough lift for some light
snow by midnight through the pre-dawn hours of Sunday. Simulated
reflectivity shows light snow moving into the western Twin Tiers and
northeast PA, but struggling to move much further northward than
that as the base of the shortwave swings through by early Sunday
morning.

Much of the area may see a brief break in snow showers after sunrise
behind the exiting shortwave, but we will not rule out some
lingering flurries or rain/snow showers while yet another deepening
upper trough begins to swing into the lower Great Lakes. This will
touch off better chances for snow, and rain or a rain/snow mix in
the lower elevations, during the afternoon and evening. A shove of
colder air behind this with northwesterly flow should keep in
lingering lake effect snow overnight into early Monday morning.

Now, as for totals. While we have chances for snow through most of
the remainder of the weekend, snowfall rates are looking light.
There is a question of whether we can really get much snow growth at
all. Model soundings show a rather shallow snow growth zone of only
a couple thousand feet. There is only a brief window tonight where
we get any decent saturation through that layer, though soundings
Sunday evening/night show better saturation especially southeast of
Lake Ontario. Snow ratios will peak in the 10-13:1 range tonight and
tomorrow night, but fall below 10:1 especially for the lower
elevations tomorrow afternoon. With fairly light QPF, this will
yield totals for the rest of the weekend generally in the 1-3 inch
range. Will continue to highlight this in the HWO given that there
will be light accumulations for the Monday morning commute, but will
not issue any headlines.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
Snow showers will continue Sunday night as the low tracks across the
NY Thruway corridor. The low should clear the CWA by Monday morning.
NW flow on the backside of this clipper will usher in lake effect
snow showers across the Finger Lakes...Mohawk Valley...and Oneida
county through the early afternoon. A weak surface ridge will build
in from the southwest...limiting the lake effect showers to light
showers or flurries into the evening. Accumulations from lake effect
showers should not exceed an inch.

Another clipper system will approach from the NW on Monday
night...bringing another chance of snow showers stretching mainly
from the Finger Lakes to Oneida county. Atmospheric moisture will be
lacking with only a few hours of saturation on the dendritic growth
zone Tuesday afternoon. The weak nature of this clipper combined
with a poorly saturated atmosphere result in expected snow
accumulations around a half inch at most. The clipper is expected to
fizzle out as high pressure builds into the southern portion of the
CWA by early evening.

Lows will be in the mid 20s Sunday night...warming to the low 30s on
Monday. NW flow behind the exiting clipper will allow lows Tuesday
morning to drop into the mow 20s across the area with upper teens on
the higher peaks in the Catskills. The ridge building into the area
Tuesday will allow for temps to warm into the mid 30s with upper 30s
in some of the warmer valleys.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A surface high pressure system over the Mid-Atlantic will
extend its influence into the southern portion of the
CWA...helping to reduce cloud cover over the area. The
positioning of the high will also bring a west wind over the
area...helping to generate some lake effect showers Tuesday
night into the afternoon hours. The high will slowly move
east...pushing lake effect showers to the north and out of the
area by Wednesday evening. Models are starting to come into
agreement on the next shortwave pushing through the area on
Thursday. Currently, the low is centered north of the
area...which would allow for rain showers changing to snow as
the front moved through the CWA sometime in the afternoon or
evening. NW flow behind the cold front would bring lake effect
showers to the CWA overnight Thursday. After this shortwave
moves through...model guidance very uncertain on the location
and timing of the next shortwave that may develop Friday or
Saturday. Current forecast is a for the end of the week is a
blend with PoPs reduced to the chance range due to this
uncertainty.

Temperatures will warm up with the high pressure influencing the
area Wednesday and the warm air advection ahead of the low on
Thursday. Highs Wednesday will be  in the low 40s with highs on
Thursday reaching the upper 40s to low 50s in the warmer valleys.
Temps drop back into the upper 30s to low 40s Friday after the
passage of the front on Thursday. Lows will be in the upper 20s to
low 30s for the forecast period.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Currently all terminals are VFR though some lake effect snow
showers are headed towards RME so a tempo was put in for a few
hours until 3z when the winds shift more southerly aloft and cut
off the lake moisture. A warm front lifting into the region
will spread snow from SW to NE with AVP and ELM seeing snow
starting around 4Z and BGM and ITH starting around 5Z. As the
front lifts north, lift weakens and the front runs into dry air
so RME and SYR likely will not see snow until that air can
saturate, which it may not even with this initial wave of snow
tonight.

Tomorrow, low stratus south of the warm front keeps cigs at or
below 2k feet at all terminals but SYR and RME who will still
have some dry air near the surface keeping cigs elevated until
the afternoon. A more robust shortwave moves in late tomorrow
afternoon after 21z helping to lift the warm front through SYR
and RME, lowering cigs. This wave also helps enhance the snow
again though this round looks more showery and better lift
through the dendritic growth zone means there is a better
chance of IFR or worse at terminals impacted by these snow
showers. Confidence was too low at this time to include tempos
at this time since the timing and locations of most widespread
snow showers is still uncertain.

Outlook...

Sunday night through Monday...Another system developing to our
southwest will bring a period of light snow and snow showers
with associated restrictions to much of the area.

Tuesday through Thursday...Continued chances for on and off snow
showers and associated restrictions as weak waves combine with
lake effect for mainly the NY terminals.

&&

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

&&

$$
SYNOPSIS...BJT/HLC
NEAR TERM...BJT/HLC
SHORT TERM...JTC
LONG TERM...JTC
AVIATION...AJG


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