344
FXUS61 KCTP 021118
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
618 AM EST Tue Dec 2 2025

.SYNOPSIS...
* The first widespread snowfall of the season is underway. Will
  be over by late morning in west and in the early aftn east.
* Arctic cold front will deliver snow showers/squalls and much
  below normal temperatures Thursday and Friday
* Reinforcing cold blast will ensure the first part of December
  will be colder than the historical average with the potential
  for another storm system this weekend or early next week

&&

.NEAR TERM /THROUGH TONIGHT/...
Inverted trough will close off today as fast southwesterly flow
aloft keeps things moving. Current 1025mb high over New England
is not going to put up much of a struggle. Sfc low tracks over
or just off the DelMarVA peninsula and then off the NJ coast.
This is a favorable storm track for snow over PA. Nrly wind will
keep cold air in place for much of the time. But, with the high
retreating and the short time of the best moisture plume and
lift over the CWA, the potential for deep snow (6+") is not
strong. The highest potential for 6+" snow amounts is generally
confined to the higher elevations of the Poconos. Many models
make the heaviest snow accums along an axis from AOO-RVL-SEG-
AVP. The most recent NAM and GFS both hint that the axis may be
a short distance (20-40sm) southward. They also keep the srn
part of Lanc Co warm enough to be plain rain for all but the
beginning 1-3hrs. Still, the rates could near 1"/hr in spots. No
real deviations made from going forecast in most if not all
respects due to high continuity. WPC guidance is highly similar,
leading to even stronger confidence. BFD has already been down
below 1sm in SN, but just to the south at OYM and DUJ, the dry
low levels are holding out (for the moment) - keeping the snow
from reaching the ground there. Best lift and hope for
mesoscale banding and 1+"/hr rates still looks like it`ll be
between 11Z-16Z. Thought about pulling the advy from Lancaster
Co, but the advy can still be valid if they can squeeze out 2"
and/or get any freezing rain. This is not a favorable
situation/setup for freezing rain in the first place and if it
does occur, it will have snowed a little before hand. That would
make it easier to plow/shovel away - or even notice it at all.
We will keep all headlines in place with timing the same, too.
By 11 AM, the steady snow will be out of the Alleghenies and
Laurels, and by 2 PM it should be done in the east. Upslope flow
does bring in lake moisture to the favored west-facing slopes of
the Laurels for the afternoon and first half of the night,
though accums should be <1".

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Upper trough axis is through the area around 03Z. 8H temps do
drop to around -10C in the N and even get close to -5C in the
SE. The clouds and --SHSN lingering in the west should go away
quickly on Wed AM. High pressure does pass to our S on Wed,
allowing the flow to come back out of the SW. Layered clouds
build in from the NW again. A true arctic front will cross LE by
sunrise Thurs. This should kick up numerous SHSN and perhaps
some squalls along the front, too. Time of day for frontal
passage is not the best for squalls, as the instability will be
limited to what warmth can be mustered as the air over the lakes
is brought over PA. The moisture is also limited to only what
the lakes can yield. We`ll only manage about 10-15F diurnal rise
on Wed, and the SW flow Wed night ahead of the cold front will
keep mins generally 20-25F (again only a 10-15F drop).

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Thursday will be the frontal passage - either very early AM in
the NW and late AM or mid-day in the SE. The moisture rapidly
disappears as the front goes into the Central Mtns. As mentioned
above, the time of frontal passage is not that favorable for
squalls due to lack of instability/higher stability normally at
that time of day. But, the air airmass is much colder behind the
front. Knock 3-5F off the maxes from Wed to Thurs.

Friday continues to 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.

The threat of winter weather for late week/early weekend seems
to have decreased with the most recent cycle of guidance, but it
has not disappeared. EC most willing to generate snowfall for
our SErn counties as the low passes to our south on it`s progs.
GFS keeps the wave moving and does not allow it to move far
enough north to put down any snow over any of PA. Regardless, a
prolonged stretch of colder than normal temperatures and an
active storm track looks to continue into next week.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Widespread IFR flying conditions in light to moderate falling
snow will continue across the airspace through about mid day.
Forecast timing on track. Snow will taper to VCSH during the
afternoon. Confidence in -RA mixing in with the -SN would be
highest (~80%) at KLNS. The melting line should stay south of
KMDT but have a confidence of about 40% that some -RA could
briefly mix in there before the precipitation ends.

As the storm system moves east of the area Tuesday afternoon,
expect northwest winds to increase to 10-15KTS. This may cause
some nominal restrictions in visibility in BLSN but confidence
is too low to warrant wording that far out in the forecast.

Outlook...

Wed-Sat...Trending drier, lingering snow across NW PA. Gusty
winds return Thu aftn.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 PM EST this afternoon for
PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-
049>053-056>059-063>066.

&&

$$

SYNOPSIS...Dangelo/NPB
NEAR TERM...Dangelo/NPB
SHORT TERM...Dangelo/NPB
LONG TERM...Steinbugl/Banghoff/Colbert
AVIATION...Gartner/Tyburski