013
FXUS61 KBGM 212339
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
639 PM EST Thu Nov 21 2024

.SYNOPSIS...
A strong low pressure system rotates through the region this
evening and overnight bringing measurable snowfall to the
region. This low looks to linger near New England through the
weekend with lake effect showers possible. Another cold front
then follows with another chance of rain and snow showers early
next week.

&&

.NEAR TERM /THROUGH FRIDAY/...

630 PM Update...

Temperatures are running slightly colder than originally
forecast, however that still has not translated to accumulating
snowfall as of yet. Snowfall rates should increase later tonight
and that will be the best chance for snowfall accumulation,
especially if temperatures continue to hover between 32 to 35
degrees. The best frontogenical forcing will arrive in our
eastern forecast counties (Catskills) around midnight and
slowly pivot westward. Expect the heaviest snow to fall across
the Twin Tiers and into portions of Central NY in the early
morning hours (2AM - 8AM). Still thinking that accumulations are
going to be highly dependent on elevation, but will continue to
monitor the evolution of banding and temperature trends over the
next few hours.

330 PM Update...

Deep upper level low and a surface low continues to rotate across
our region this afternoon with wrap around precipitation. Rain
showers expand over most of our region with temperatures ranging in
the upper 30s to low 40s. As the afternoon progresses some higher
elevations could see a mix of rain and snow start to sneak in.
Although majority of the transition will occur late afternoon
through early evening. As temperatures begin to fall, precipitation
is expected to fully transition over to snow and continue
during the overnight period. Placement of the upper level jet
puts our region in the left exit region, enhancing lift.
Otherwise 700 MB Frontogenesis continues to show strong signals
of banding moving into the western Catskills region and into the
Twin Tiers. Snowfall rates under the band have the potential to
be 1-3+ inches per hour for several hours. The most favorable
time frame for heavy snowfall is between 03Z to 09Z.

Snow ratios have trended higher this update but continue to
vary across the region. When heavier snowfall rates occur we
should be able to get a more typical of a 10:1 ratio. Therefore
snowfall totals look to be maximized at higher elevations under
the intense bands. Keep in mind that even lower elevations could
get relatively decent accumulations in areas where banding sets
up. Models have also trended slightly higher in terms of
snow totals and slightly further into our region. As a result a
winter storm warning was expanded further north and west with
snow totals ranging 1-4 inches in valley locations and 6-12
inches in elevations above 1,500 feet. An advisory was also
expanded to include borderline counties that could be impacted.
This was mainly to account for the uncertainty of where exactly
these bands will develop and how far into the region they
expand.

In terms of the progression, low pressure system will loop around
the region pulling in moisture off of the Atlantic along with
moisture off of lake Ontario. This will keep fairly widespread
showers in the forecast through the overnight period. A dry
slot begins to work into the system Friday morning mainly cutting
off showers in central NY. Some showers may survive especially
in northeast PA, but should remain more isolated in nature
throughout the day. Highs on Friday return to the upper 30s to
low 40s, therefore a mix of snow and rain expected.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
210 PM Update

This period will start off with the departing low pressure system
off the east coast. This will bring a slight chance to low end
chance for a few lingering rain and snow showers as overnight
temperatures eventually dip down into the upper 20s and 30s...little
to no additional snow accumulations is expected overnight. Saturday
will see a cool, blustery northwest flow pattern over the area with
some developing lake effect showers, especially in the afternoon and
evening hours. Precipitation type will be all rain showers during
the day, with highs in the upper 30s and 40s. Some snow showers mix
in off of lake Ontario for Saturday night, as 850mb temperatures
fall to around -5C and overnight lows drop into the 30s. Any light
snow accumulations will be under a half inch over the higher hills
of Central NY; south of Syracuse and Utica area.

Lingering lake effect rain and snow showers Sunday morning,
dissipate and and conditions dry out areawide by the afternoon as
high pressure moves in. Skies remain mostly cloudy to overcast
though, ands still seasonably cool with highs in the upper 30s to
mid-40 expected. High pressure moves overhead Sunday night with
partial clearing, light winds and chilly lows in the 20s to low 30s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
210 PM Update

This period starts off with mainly quiet weather for Monday with
mild temperatures expected. Clouds will increase through the day,
and a few late day or evening rain showers are possible for Central
NY as a weak warm front pushes north out ahead of a surface low over
northern Michigan. The low then brings a cold front through the
forecast area Monday night into Tuesday, with a colder air mass (-6C
at 850mb) and a northwest flow re-establishing over the Northeast
US. This will bring more lake effect rain, and eventually lake
effect snow showers mainly to Central NY...with NE PA staying on the
drier side. Some lake effect showers linger into Wednesday, before
likely diminishing and tapering off.

We are closely watching the next storm system which could impact the
area around or just after the Thanksgiving Holiday (Thursday into
next Friday). Model guidance is in fairly good agreement showing a
developing low pressure system with a lot of moisture and seasonably
cold temperatures over the region. There is too much uncertainty
with this potential system being 7-8 days out to pin down any
details; but again certainly something to keep a close eye on as
we get closer in time.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Challenging and low confidence forecast in exact details on
restrictions through tonight and tomorrow. High confidence that
there will be periods of at least IFR and possibly worse
conditions, especially at ITH, ELM, BGM and AVP, where heavier
snow is expected.

Snow tapers off 12 - 15Z changes to a mix of rain/snow or back
to rain completely after 15Z. Winds will increase out of the
north and northeast with gusts 15 to 20 kt overnight and into
Fri morning.

Outlook...

Friday night and Saturday...Continued possible restrictions in
rain and snow showers, especially Central NY.

Sunday...Gradual improvement. VFR probable for AVP with MVFR
expected elsewhere. Mixed rain/snow showers far northern areas.

Monday and Tuesday... Another approaching low pressure system
could bring possible restrictions.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Storm Warning until 4 PM EST Friday for PAZ038>040-043-
     044-047-048-072.
NY...Winter Weather Advisory until 4 PM EST Friday for NYZ017-018-
     022>024-037.
     Winter Storm Warning until 4 PM EST Friday for NYZ025-036-
     044>046-055>057-062.

&&

$$

SYNOPSIS...ES
NEAR TERM...ES/MPK
SHORT TERM...MJM
LONG TERM...MJM
AVIATION...MPK