795
FXUS61 KCTP 011743
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1243 PM EST Mon Dec 1 2025

.SYNOPSIS...
* The first widespread plowable snowfall is expected Monday
  night and Tuesday, with travel impacts likely Tuesday morning.
* A strong cold front Thursday will bring lake effect snow
  showers or squalls and the coldest temps of the season thus
  far, in the single digits and low teens by Fri AM.
* The first half of December will be characterized by below
  average temperatures and an active weather pattern with
  chances for rain/snow every few days.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Today will be dry with high pressure arriving and centering
overhead. Morning clouds will slowly fade, at least east of the
Allegheny Front. Clouds will probably linger in the west with
upslope flow before high clouds move in this afternoon. Temps
will be stuck below freezing in the northern tier, but rise
through the 30s most everywhere else. A breeze this morning will
taper off to calm conditions. It may feel somewhat comfortable
outside this afternoon and evening with no wind.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A fast moving upper trough will result in this first widespread
wintry weather tonight into Tuesday. The system will be very fast
moving with a lack of a strong area of high pressure to slow
its forward momentum. A band of snow looks to arrive shortly
after midnight in the NW mountains as the right entrance region
of a jet max forces ascent overtop some modest 700 mb
frontogenesis. The upper jet will strengthen and extend
southward through the first half of Tuesday, supporting another
area of ascent over the eastern half of PA. At the same time,
warm advection in the southeast will lead to isentropic ascent
and another area of heavy snow is possible just north of the
rain-snow line Tuesday morning. Though accumulation rates may
locally approach 1 inch per hour, the limiting factor for snow
totals will be longevity. At any given location, most of the
snow accumulation will occur in just a 6 hour window. Most
likely forecast is 4-5 inches for the northern 2/3 of central
PA, with higher amounts perhaps focused in the NW and SE and a
"shadow" through the middle, and lesser amounts in the southern
tier where rain/sleet/freezing rain may mix in. Highest chance
for locally 6 inches is somewhere between Harrisburg and
Williamsport and points east, maybe the higher terrain of
Schuylkill or Sullivan Counties. Precip tapers off late Tuesday
afternoon as RH quickly drops above the 700 mb level.

The latest Winter Storm Outlook highlights a 30-50% chance of
Warning criteria snowfall (6"+) in northeast PA, primarily east
of US-15. GEFS and ECENS probabilities of 6"+ also support the
30-50% probability in the Poconos, with an even higher
likelihood up through coastal New England. The GEFS paints the
highest snowfall totals in Sullivan county northeast toward
Albany, while the operational GFS is about 40 miles farther
south, with the main line of heavy snow, from Lebanon through
Schuylkill northeast. Leaned heavily on the ensemble consensus
and kept the Watch in effect for Sullivan, Columbia, and
Schuylkill where the combination of higher elevation & longer
duration 1"+ per hour rates make Warning amounts (6"+) within
the realm of possibility. Boom potential (higher amounts than
forecast) exists just north of the rain/snow line, which could
set up as far southwest as the I-81 corridor. Lebanon and
Dauphin County could see higher amounts than currently forecast.

Elsewhere, a plowable snowfall is likely for almost all of
central PA. Opted to issue a Winter Weather Advisory for all
counties outside the Watch for snow (and some ice potential
toward the Mason-Dixon line). Guidance has remained consistent
overall for snowfall amounts with the last two runs, however
some uncertainty remains whether or not warm nosing above the
surface could limit snow across the PA/MD border into south
central PA and the lower Susquehanna Valley. If mixing is a
problem for anywhere in central PA, it would probably be for
locations southeast of US-30 in York and Lancaster County.
Continue to monitor the forecast today and tonight as minor
details could have big impacts on observed snowfall amounts.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
High pressure builds in Wednesday with a reinforcing cold front
moving through Wednesday night into Thursday. This will likely
produce some light snow across the northern tier. This front
will be a true Arctic front with a pretty good push of cold air
behind it. As such, there will probably be line of snow
showers/squall along the leading edge of the front. Current
guidance indicates the front could be along the I-99/US-15
corridor by midday, and continue to push east. We`ll be able to
nail down the timing of the event quite well given the linear
mode (contrasted with a cellular mode that is much more
complicated to time out).

Thursday night and Friday look quite cold, with lows in the
single digits and teens while highs only make it into the 20s to
low 30s. Otherwise, temperatures will be fairly consistent for
the upcoming week and weekend, with highs in the 30s and lows in
the teens and 20s.

By next weekend, another storm system looks to affect the
Midwest and northeast US. Considerable uncertainty remains with
the low track of this system. A track northwest of PA would
lead to snow changing to a wintry mix and rain, while a track
southeast of PA could look pretty similar to Tuesday`s system
with primarily snow. Regardless, a prolonged stretch of cooler
than normal temperatures and an active storm track through the
northeast looks to continue into the first week (and more) of
December.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
The remainder of today will stay generally VFR across the
region. High clouds remain present and will continue to stream
in and lower ahead of the system expected to arrive tonight. A
widespread snowfall will arrive Monday night into Tuesday as
low pressure develops and moves up the New England coast Tuesday
afternoon. Confidence in high in visibility restrictions and low
cigs due to snowfall as it spreads from west to eat. Impacts
will begin as early as 05-06Z across the western terminals. All
airfields will likely experience IFR or lower conditions by 12Z
Tuesday morning. This will be a quick hitting storm system, and
precipitation should taper off sometime shortly after 18Z.

There is a some uncertainty as to where the snow-rain line will
set up late Tuesday morning as temperatures warm up to just
above freezing in the southeast. Currently the only site
expecting to see a rain snow mix will be LNS after 15Z. However,
that transition zone could drift a little further north and some
mixed precipitation could reach MDT before the system moves off.

Outlook...

Tue...Snow likely with widespread restrictions, before a
possible mix later in the day across the south. Restrictions
possible.

Wed-Fri...Trending drier, lingering snow across NW PA.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM to 1 PM EST Tuesday for
PAZ004>006-010-011-017-024-033-034-037.
Winter Weather Advisory from 3 AM to 1 PM EST Tuesday for
PAZ012-018-019-025>028-035-036-045-049>052-056-057-059-063>066.
Winter Storm Watch from late tonight through Tuesday afternoon
for PAZ041-042-046-053-058.

&&

$$

SYNOPSIS...Banghoff/Colbert
NEAR TERM...Banghoff/Colbert
SHORT TERM...Banghoff/Colbert
LONG TERM...Banghoff/Colbert
AVIATION...Bowen