Cranberry, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

790
FXUS61 KBGM 180914
AFDBGM

Area Forecast Discussion
National Weather Service Binghamton NY
414 AM EST Sat Jan 18 2025

.SYNOPSIS...
The next cold front will bring a mix of rain and snow to the
area today. Colder air moves in tonight and the next chance of
snow arrives Sunday. Some areas of northeast PA and southern NY
will see accumulating snowfall. Very cold Arctic air will settle
into the region Monday through at least Wednesday.

&&

.NEAR TERM /THROUGH SUNDAY/...
415 AM update..
Primary concerns in the near term are focused on the weak
system moving through today, cold air pushing in tonight and the
coastal low developing and moving along the East Coast on
Sunday with the potential for significant accumulating snow.

The Winter Storm Watch in effect for portions of northeast PA
and Sullivan County NY was expanded slightly to include Delaware
County NY and also Wyoming and Susquehanna Counties in PA.

For Today, the amplified ridge axis that moved through
yesterday is well off the New England coast as of this morning,
but there is still the remnants of the low level jet and warm
nose lingering across parts of the interior Northeast. This
pocket of warm southerly winds is allowing for some relatively
warm temperatures (upper 20s to mid 30s) across the region along
with occasionally gusty south winds (up to 20-25 mph). An
incoming upper short wave and associated surface cold front will
push through during the day today and initially produced light
snow on the front end this morning. However, with weak heating
during the afternoon, especially in the valley and lower-
elevation locations, surface temperatures will warm slightly
above freezing and allow for a mix of rain and snow showers.
There could be pockets of heavier precipitation in the
afternoon, which could switch the mix over to all snow. However,
snowfall accumulations should remain below an inch except
across northern Oneida County in NY where the precip may remain
snow all day and 1-3 inches of snow is possible.

For Tonight, an cooling air mass and pattern shift will occur
as the wind flow shifts to the northwest and colder air starts
to filter in. Temperatures in the upper 20s and lower 30s this
evening will cool into the lower 20s by Sunday morning. The
lingering snow showers this evening will taper off and most of
the snow should end during the overnight hours.

For Sunday, the stage will be set for a period of accumulating
snow due to the development and strengthening of a coastal
surface low just off the NJ coast.

Antecedent cold, sub-freezing air near the surface and
throughout the column will create favorable conditions for snow
production as this system passes by to the east. From the
synoptic level, a positively tilted upper trough over the Ohio
Valley/Great Lakes will become negatively tilted during the day
Sunday and lift newd through the Northeast US. An embedded short
wave and 300mb jet streak will induce an area of strong
vertical motion on the leading edge of this trough and act to
deepen the surface low with time. This entire system will
translate northeastward later Sunday and Sunday night and seems
to be well simulated with most of the deterministic model
guidance.

The details of the mesoscale forcing features remain the area
of greatest challenge. The exact position of the strengthening
surface low will play a large role in the location of the low
level baroclinic zone and formation of the frontogenetic layer.
The consensus seems to be along a sw to ne line extending from
e-central PA into New England, with warm air to the southeast
and the cold air remaining in place to the northwest. This
position of the f-gen layer would then allow the heaviest snow
to set up just to the north/nw...roughly from the Poconos into
the southern Catskills.

The uncertainties remain centered around the exact location of
this layer of fgen. Any east or west movement of this forcing
could shift the band significantly. We are also starting to see
some indication of mesoscale banding and weak CSI. The NAM/GFS
and Canadian model guidance is indicating the presence of
negative EPV overlapping with some of the aforementioned low-
level fgen, which is usually an indication of potential banding
snowfall and enhanced snowfall rates. The HREF WPC Snowband
Probability Tracker is within spatial range of this event and is
starting to pick up on this potential as well.

Due to some of the items mentioned here and the fact that there
is a slightly increased concern for westward extent of the
heavy snow, we have decided to expand the Winter Weather Watch
slightly to the west/nw. This still does appear to be a very
quick-hitting storm, with the most favorable time of heavy snow
falling from around 12 pm to 7 pm...earlier in the Wyoming
Valley and later in the Catskills.

We will likely need some Winter Weather Advisories in a tier of
counties to the west/nw, but given the uncertainty, we will
hold off at this time. A tight gradient of snowfall appears
likely with areas farther to the west and north possibly seeing
a very minimal amount of snow with this system.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
330 AM Update...

The Sunday winter storm will linger into the overnight hours as it
slides east. Another half inch to 2 inches of snowfall accumulation
will be possible east of I-81 during the first half of Sunday
night. Behind the departing system, cold, west-northwest flow
will kick off some lake effect snow showers. T850 temps will be
as low as -20 deg C. There is some uncertainty on how quickly
the storm system moves out and then how quickly the lake effect
snow develops. There is potential for a couple of inches in the
Finger Lakes region Sunday night if snow showers develop earlier
than expected. Currently the forecast has less than an inch for
this region. The 510 line (1000-500 mb thickness) drops south
of the region, indicating the arrival of an arctic air mass.
Lows will be in the single digits, though breezy winds will push
wind chills below zero.

Lake effect snow will continue through Monday night. During the
daytime, flow will favor snow over portions of CNY, though it is
uncertain exactly how the bands will set up. Most models show an
initial band that will be a combination of a Lake Erie and Lake
Ontario band. As the day progresses, some models show two separate
bands, one for each lake while others hang onto one band until the
overnight hours. Eventually, flow will become more southwesterly and
the bands will drift north of the region, though the Lake Ontario
band will clip N. Oneida at times. Despite the uncertainties, the
daytime will be the best chance for accumulations with localized
amounts  up to 2 inches possible. Then lighter amounts are expected
as the band(s) drift northward.

Temperatures will continue to plummet on Monday. Highs will max out
in the teens, though the Wyoming Valley may just reach the 20s. With
winds picking up, wind chills will be in the single digits. Clear
skies will support good radiational cooling overnight, so hourly
temperatures were bumped down using an equal blend of NBM and NBM
tenth percentile guidance. The lows were then derived from those
changes. Blustery conditions are expected as wind chills will fall
to -15 to -25 Monday night into Tuesday morning. Cold weather hazards
will likely be needed, but given it is still a few days out, this
is highlighted in the HWO for now.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
330 AM Update...

The continuation of the cold conditions will be the main concern
during the long term period. Through Wednesday, temperatures will
struggle to climb out of the single digits during the daytime hours
while falling below zero both Tuesday and Wednesday night. Wind
chills will once again fall below -15 both nights, though slight
improvements will be seen Wednesday night into Thursday morning. The
510 line will finally move back north as the cold air begins to
retreat on Thursday. Highs will climb back into the 20s by the end
of the week though single digits will still be possible for some
during the overnight hours.

A nearly week-long lake effect event is in store for the long term
period though west to southwest flow will keep most of the snow
north of the region. Still, on and off snow showers will be possible
across far northern portions of the region. Meanwhile, high pressure
will keep two separate coastal systems just out of the region
Wednesday and Friday. However, shifts in these tracks will be
possible over time, so both will need to be monitored throughout the
week.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
A weak wave will move through the region later today and cause
the current VFR conditions to drop to MVFR after 15Z with some
light rain mixing with snow into the afternoon. There could be
periods when the precipitation intensifies for short periods of
time. During these 1-2 hour windows in the afternoon, vsbys
could drop to IFR or less. The rain/snow showers will slowly
taper off after 22Z and make way for the colder and drier air
expected to move in after 02Z. East/southeast winds this morning
will become more southerly later today and then veer more to the
northwest Saturday evening.

Still expecting a period of LLWS at most terminals through 12Z
this morning due to a modest low level jet.

Outlook...

Saturday night...Mostly light lingering snow showers with
minimal restrictions.

Sunday...Some snow and associated restrictions possible. The
most favorable location will be AVP due to a passing coastal
low.

Monday through Wednesday...Lake effect snow showers and
associated restrictions possible, especially for KSYR-KRME.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Storm Watch from Sunday morning through late Sunday
     night for PAZ039-040-043-044-047-048-072.
NY...Winter Storm Watch from Sunday morning through late Sunday
     night for NYZ057-062.

&&

$$

SYNOPSIS...BJT
NEAR TERM...BJT
SHORT TERM...BTL
LONG TERM...BTL
AVIATION...BJT