382
FXUS61 KCTP 080155
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
855 PM EST Fri Feb 7 2025

.SYNOPSIS...
* Wintry mix will impact the area Saturday afternoon into
  Saturday night
* The active early February winter weather pattern continues
  next week with additional rounds of snow or ice possible next
  Tuesday through Thursday

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Surface high pressure tracking across Northern PA will support
clear and seasonably cold conditions this evening across the
region. The area most favorable for radiational cooling will be
over the N Mtns, due to the presence of drier air and some snow
cover. Would not be surprised to see some single digit lows in
this area later tonight.

Otherwise, expect thickening high and mid level cloudiness late
tonight associated with warm advection aloft ahead of an
upstream trough. The increasing clouds should put the brakes on
the radiational cooling, with readings leveling off or rising
before dawn. Expect temps at daybreak to range from the low
teens in the coldest valleys of the northern tier, to the mid
and upper 20s in the Lower Susq Valley.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
Low pressure lifting up the Ohio Valley, combined with high
pressure channeling down the east side of the Appalachians will
set the stage for another overrunning/CAD wedge type wintry mix
event Saturday into Saturday night, as strong WAA at the nose
of a 60kt low level jet overruns the retreating cold sector.

Latest guidance from the NBM, HREF and WPC continues to favor
the highest probs for plowable snow accums over the northern
tier of the state, where 1-3 inches appear likely. This data
also supports ice accretion up to 0.3 of an inch in the Laurel
Highlands down into western MD. A transition zone of IP/ZR
(perhaps following a short burst of snow) is most likely from
I80 south to the MD line, where around an inch of snow/sleet
and 0.1-0.2 inches of ice is forecast.

Latest model guidance indicates most likely onset times of
wintry precip range from around 15Z south of the turnpike from
Somerset to Franklin counties, mid afternoon along the I-80
corridor and early evening over the northern tier counties.

Model guidance shows some elevated instablity working into the
southwest corner of the forecast area late Saturday. Would not
be surprised to see some ltg or rumbles of thunder in this part
of the state Sat evening, as large scale forcing ramps up ahead
of the mid level trough.

Overall, this is a quick hitting wintry mix event with the
heaviest mixed pcpn expected from the early evening through the
first part of Saturday night. Expect the precipitation to
rapidly taper off from west to east between 04Z-07Z, as the
surface low tracks along the Mason Dixon Line and the low level
jet/best WAA exits the area. A shallow layer of residual
moisture behind the exiting low, combined with an upsloping
northwest flow, may yield some lingering patchy freezing
drizzle or snizzle over the Allegheny Plateau during the pre-
dawn hours of Sunday.

Sharp pressure rises are noted in the model guidance Sunday
morning, as the strengthening low passes off the NJ coast,
signaling the onset of gusty northwest winds. Bufkit soundings
and EPS plumes indicate gusts around 35kts are likely Sunday
over the Laurels and SC Mtns, with somewhat lighter winds
elsewhere. The gusty winds could have some post-storm impact
over the Laurel Highlands in terms of a continued threat of
downed tree limbs and isolated power outages.

High pressure building into the state should cause any lingering
orographic snow showers over the W Mtns to taper off Sun PM.
Model RH profiles indicate a fair amount of stratocu Sunday over
the W Mtns, while subsidence the lee of the Mtns provides
partly sunny skies over the Susq Valley. GEFS 2m temp anomalies
indicate near normal highs Sunday over the W Mtns and a bit
above in the Susq Valley. See no reason to deviate from NBM
maxtemps, which range from around 30F over the highest terrain
of the Alleghenies, to around 40F in the Susq Valley.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Active weather is anticipated through the extended period with
multiple systems expected to impact Central PA. However, high
pressure will provide a brief period of dry weather Sunday night through
Monday.

By Tuesday, all guidance shows an area of low pressure
developing and tracking just south of Pennsylvania through
Wednesday morning. There is still a considerable amount of
spread in the different model suites as to the exact track of
this system as well as the timing, but most ensemble members
show it tracking far enough south to support a nearly all snow
event. While the eventual track of the system will determine
where exactly the heaviest snow will fall, both the GEFS and
ECENS suggest that a swath of moderate to heavy snow will be
possible across the southern tier of Central Pennsylvania.

Another system is likely to move through the region Wednesday
night into Thursday, but ensemble spread is even larger than
with the Tuesday storm. The exact details will have to be ironed
out as we get closer to the event, but another period of wintry
precipitation appears likely.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions will prevail through most of tonight with mainly
clear skies to begin the 00Z TAF package. Clouds will be
increasing early Saturday morning ahead of the surface low
expected to move up the Ohio Valley.

Confidence is increasing on impactful weather late Saturday
morning into Saturday afternoon. Precipitation will begin as
snow across JST and AOO first before overspreading across the
rest of central PA airspace through the early afternoon hours.
Sleet will likely be mixed in with snow as temperatures in the
mid levels warm to slightly above freezing near 18Z. By 20Z
Saturday the western sites of JST/AOO will have transitioned to
freezing rain with all other airfields likely to transition
within 1 to 3 hours after the southwestern sites. Expect IFR to
LIFR conditions at all sites by Saturday evening.

Freezing rain and sleet will transition to plain rain across
southern PA for JST/AOO/MDT/LNS after 03Z Sunday, but the
remainder of the area will likely remain a wintry mix.
Precipitation will eventually trail off for most sites by
sunrise Sunday morning, but low ceilings could continue to cause
sub VFR conditions well into Sunday afternoon.


Outlook...

Sat...Sub-VFR restrictions associated with snow and wintry mix
mainly from the afternoon through Saturday night.

Sun...Sub-VFR cigs possible, especially over the western
airspace.

Mon...A slight chance of snow over south central PA.

Tue...Snow and IFR restrictions possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 3 PM Saturday to 3 AM EST Sunday
for PAZ004-010>012-017>019-045-046-049>053-058.
Winter Weather Advisory from 5 PM Saturday to 3 AM EST Sunday
for PAZ005-006-037-041-042.
Ice Storm Warning from 1 PM Saturday to 3 AM EST Sunday for
PAZ024-033.
Winter Weather Advisory from 1 PM Saturday to 3 AM EST Sunday
for PAZ025>028-034>036-056-057-059-063>066.

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Bauco
AVIATION...Bowen