841
FXUS61 KCTP 301219
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
719 AM EST Tue Dec 30 2025

.SYNOPSIS...
* Gusty winds and lake effect snow showers will bring hazardous
  travel to Central PA once again today.
* A weak clipper system will bring light snow to Western and
  even parts of southern PA tonight.
* A more significant system and second surge of arctic air will
  bring several inches of snow to locations west of US-219 on
  New Years Eve, along with a threat of snow squalls along the
  frontal boundary.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Wind chills this morning will range from zero to 5 below
  across the Northern and Western Mountains of PA to the single
  digits and mid teens elsewhere.
- Frequent wind gusts over 40 mph are expected at least through
  this morning, with high end gust potential over 60 mph over
  the Laurel Highlands and points immediately to the east.
- Another round or two of significant lake effect snow
  accumulation is expected over northwest PA.

--------------------------------------------------------------

Continued strong low-level west-northwest flow with vertical
mixing between 3-4 KFT AGL will continue to tap 40-50+ KT wind
this morning from just 2-3 KFT AGL and mix it down to the
surface in wind gusts of similar magnitude.

Peak gusts should gradually decrease late this morning through
this afternoon, but should still be gusting into the 30s (KTS)
later today through this evening based on multi-model forecast
sounding data.

Frigid wind chills will be an issue this morning (apparent
temperatures +/- single digits). These values don`t quite reach
cold weather headline criteria (-10F).

A favorable WNW LLVL fetch off the lakes along with upslope
effects (and pulses of omega within the DGZ) should support
efficient snowfall accumulation in the Laurels through this
afternoon as well. Extended the Lake Effect Snow Warning across
NW PA through 12Z Wed, while Wint Weather Advisories further
south will be allow to expire at 18Z today.

Outside of the Wint Weather Advisories and Warnings, narrow and
slowly moving bands of LES will continue to bring mainly light
accums of a coating to 2 inches.

Max temps today will range from about 20F across the NW Mtns and
ridge tops of the Laurel Highlands to around 32F across the
larger metro areas in SE PA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Snow showers and areas of more persistent, heavier LES will
retreat to the north and possibly out of our CWA temporarily as
the mean flow within the well-mixed layer backs to about 240
deg later tonight through Wednesday.

Hi-res guidance depicts a compact shortwave drifting southeast
across western PA on this evening into Wednesday morning. This
will bring additional, mainly light, snowfall accumulation to
the laurel highlands and southern 1-2 layer of PA counties,
thanks to enhanced and deeper Uvvel beneath the left exit region
of a 100-100 kt upper level jet that will be moving along/over
the Mason/Dixon Line.

A local enhancement of snow in the northwest mountains could
also necessitate a short-fused Advisory, but impacts should be
fairly limited. In the wake of the shortwave, winds shift around
to a more westerly fetch, which should also direct lake effect
snow bands back into the NW Mtns, especially to the North of
Route 6.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
On the large-scale, a cold, cyclonic NW flow pattern will reside
over much of the eastern CONUS this period, underneath a deep
upper low in eastern Canada. On Wednesday afternoon (New Years
Eve), a wave of low pressure will drift eastward across the
Great Lakes, and drag an Arctic front south through the
Commonwealth. Underneath a favorable left exit region of an
upper jet, this front could produce a threat of snow squalls
late Wednesday evening into the New Year. Anyone planning to
travel for the New Year should be prepared for the risk of snow
squalls. If a Snow Squall Warning is issued, delay travel or
exit the highway at the next opportunity. A snow squall produces
blizzard-like conditions with gusty winds, heavy snow, and
significantly reduced visibility.

In addition to the threat of snow squalls, fairly robust
moisture associated with this system will bring a more potent
batch of snow to the region. Snowfall totals over 4" are
possible west of US-219 with localized amounts >6" in the higher
elevations of western Somerset County as well as in the typical
lake effect zones of northwest PA. A Winter Storm Watch is now
in effect for Somerset County from 4PM Wednesday through 10AM
Thursday for the significant snowfall potential on the western
ridges. Additional Watches/Warnings may be needed in northwest
PA along with advisories along the spine of the Alleghenies if
confidence continues to increase.

In the wake of this system, a reinforcing shot of arctic air
later Thursday into Friday should support wind chills in the
single digits and teens once again. Then, temperatures should
gradually moderate this weekend, as heights aloft slowly start
to build.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Widespread VFR outside of lake effect and upslope snow showers
that will continue to impact BFD/JST with high (~80-90%)
confidence, AOO with moderate (~50-60% between 12-14Z Tue) and
UNV/IPT with low (< 30%) confidence. Recent GLAMP guidance
outlines IFR visibilities within snow showers through ~18Z Tue,
which matches current 12Z Tue observations fairly well. Brief
periods of LIFR will be possible, mainly at BFD/JST between
12Z-15Z Tue where locally heavy snow bands could make runs at
the airfields. Even with snow showers subsiding at BFD/JST, a
combination of NBM/GLAMP/HREF model guidance continues to
outline a pesky low-level cloud deck (between 1500-2500ft AGL)
continuing throughout the entire 12Z TAF package. Given this
reasonable agreement based off of RAP model soundings, there is
moderate-to-high (~70-90%) confidence in MVFR persisting. Model
guidance does reintroduce snow shower chances across western
Pennsylvania after 00Z Wednesday with best chances for snowfall
(~50-60%) at BFD/JST. Further south/east, models show some
disparities, thus have limited mentions to UNV/AOO/IPT where
there remains approximately a 30% chance of snow making it into
the airfield.

A slight decrease in winds have been observed overnight across
central Pennsylvania with only isolated instances of gusts
exceeding 40kts over the past couple of hours. Winds will
continue to gust above 30kts, especially at higher elevation
locations such as BFD/JST/AOO over the next couple of hours
along with eastern terminals (IPT/MDT/LNS) before gradually
decreasing after 18Z Tue. Gusts upwards of 20-25kts appear more
plausible, with LLWS concerns minimized as the 850mb LLJ has
shifted east of the forecast area.

Outlook...

Wed...Chance of snow showers across the north and west, dry
southeast.

Thu...Chance of snow showers.

Fri...Mainly dry. Slight chance of a snow shower at BFD.

Sat...VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until noon EST today for PAZ004>006-010>012-019-
026>028-035>037-041-042-045-046-049>053-056>059-063>066.
Lake Effect Snow Warning until 7 AM EST Wednesday for PAZ004-
005.
Winter Weather Advisory until 1 PM EST this afternoon for
PAZ010-017-024-033.
High Wind Warning until 4 PM EST this afternoon for PAZ017-018-
024-025-033-034.
Winter Storm Watch from Wednesday afternoon through Thursday
morning for PAZ033.

&&

$$

SYNOPSIS...Jurewicz/Lambert
NEAR TERM...Jurewicz/Lambert
SHORT TERM...Jurewicz/Lambert
LONG TERM...Jurewicz/Lambert/Banghoff
AVIATION...NPB