NWS Forecast Discussion

001
FXUS61 KCTP 150741
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
241 AM EST Sat Feb 15 2025

.SYNOPSIS...
High pressure moves offshore tonight. Strengthening low
pressure approaching from the Ohio Valley on Saturday will lift
across Pennsylvania Sunday. Another widespread wintry mix of
snow, sleet, freezing rain Saturday into Sunday. More than a
quarter inch of ice is expected on ridgetop locations of the
Alleghenies, while locally heavy rain over 1 inch is possible
over the Laurel Highlands, causing rises on smaller creeks and
streams. Another blast of wind and much colder air follows the
weekend storm to start the upcoming work week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Surface high pressure along the Mid Atlantic coast will provide
Central PA with fair and seasonably cold conditions tonight.
Warm advection aloft in advance of an upstream trough is already
spreading high clouds over the region this evening, and model
soundings support thickening cloud cover late tonight as the
approaching low level jet arrives from the Ohio Valley. Latest
guidance indicates light snow will be on the doorstep of the
Laurel Highlands by daybreak Saturday.

Thickening cloud cover should keep temps from falling too far
tonight, with expected min temps ranging from the mid and upper
teens over the N Mtns, to the mid 20s over the Lower Susq
Valley.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
Most details of going forecast in good shape for the next winter
potpourri to affect central PA Saturday through Sunday morning.
A digging upper trough over the east slopes of the Rockies will
spawn a strengthening surface low over the Southern Plains
Saturday, which is then progged to lift northeast across the
Eastern Grt Lks by Sunday PM. A lead shortwave and an associated
plume of Pacific and Gulf moisture will overrun retreating cold
air over PA, spreading snow across much of the forecast area by
midday Saturday.

Model soundings continue to indicate the initial period of snow
will be followed by a transition to mixed precip Sat afternoon/evening,
then an eventual change to rain Sat night. Progged 925-700mb
max wet bulb temps imply the snow/mixed line will be over the
Laurel Highlands by noon, then rapidly lift northeast across the
rest of the forecast area between 18Z-22Z.

Most likely storm total snow/sleet amounts based on latest WPC
qpf and forecast soundings ranges from less than an inch over
the southern counties, to 1-2 inches over the north. Low level
cold air will be tough to dislodge along and east of the
Alleghenies, likely resulting in ice accretions ranging from
around a quarter inch over the ridgetops of North-Central PA, to
less than 0.10 inches in most valley locations, and probably
nothing from Harrisburg south and east.

Temperature profiles indicate that temperatures could rise
above freezing for locations south of I-80 before midnight but
ridgetop locations will likely remain just below freezing and
allow additional icing to occur overnight, thus leading to
higher ice amounts there. Meanwhile, as a warm front lifts north
of PA overnight, a several hour period of precipitation- free
conditions appears increasingly likely into Sunday morning.

Ice falling on top of snow/sleet should limit its impact to
some extent, but the combination of snow/sleet/ice will make
roads slick enough on Saturday to warrant a Winter Weather
Advisory.

Mild and showery weather is expected Sunday, as the region
breaks into the warm sector Sunday afternoon, ahead of low
pressure lifting across the Eastern Grt Lks. In all, liquid
equivalent precipitation totals should be between 1 and 1.5
inches across the entire forecast area by Sunday afternoon, with
the highest totals expected in Somerset County. The combination
of rain and snow/ice melt could lead to some areal flooding
concerns there Saturday night into Sunday night. In coordination
with neighboring offices, a Flood Watch remains in effect for
Somerset County for the potential of areal/small stream flooding
there, but most indications are that the main flooding threat
will remain to our southwest in the Ohio Valley.

A strong cold front will sweep through the region late Sunday
afternoon into the early evening, ushering in gusty winds, a
period of rain changing to snow, and dramatically colder
temperatures. Highs ahead of the front are likely to reach the
mid 50s in southeast PA Sunday afternoon. After the cold front
moves through, there is very high confidence in a 24-30 hour
period of quite strong/gusty west to west-northwest winds
sustained at 20-25 mph with gusts of 45-55 mph from Sunday
afternoon through Monday. Flurries/scattered snow showers will
be flying for Sunday night into Monday as the DGZ lowers to
occupy much of the thick stratocu layer. Narrow LES streamers
could penetrate the CWA as far SE as the Lower Susq Valley given
a well-aligned low to mid level flow averaging around 50 KTS.
By Monday morning, temperatures will have dropped 20 degrees
from Sundays highs, and daytime wind chills Monday will range
from zero to 5 below over the N Mtns, to the teens in the
Susq Valley.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
All guidance points to cold and mostly dry weather Monday night
into mid week associated with an elongated upper trough over the
Northern CONUS and surface ridging over PA. Ensemble 2m temp
anomalies indicate the coldest air relative to normal will be
over the NW Mtns, where highs Tues are likely to be in the lower
teens. Max temps over most of Central PA should be in the 20s
both Tue and Wed. EPS 2m temp plumes continue to support single
digit min temps Tue/Wed over the Alleghenies. Winds may remain
high enough early Tue AM to result in wind chills around
-10F over the N Mtns.

The focus Wed PM into Thursday is a potential East Coast snow
storm associated with the phasing of a southern stream shortwave
and a deepening upper low over the Upper Midwest. The mean
surface low track of the 18Z EPS/GEFS track the intensifying
surface low too far east to significantly impact Central PA.
However, there remains plenty of uncertainty inherent in a Day
5-6 forecast and there are a sizable minority of EPS members
that track the storm much closer to the coast, which could
result in widespread heavy snow across the region. NBM POPs
around 60pct seems prudent at this point Wed PM into Thursday.

Blustery and cold weather looks very likely to close out next
week, as the intensifying low heads NE into the N. Atlantic.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
All airfields expected to prevail VFR for most of the night in
the west and all night in the east. High pressure directly
overhead will continue sliding steadily, and rather quickly to
the east overnight. Winds will remain light tonight, out of the
SSE in the west, and E in the east, but less than 10kts even on
the high ground. However LLWS could be present across the
airspace from 08Z through late Saturday night. Bufkit soundings
suggest 35kts near 1600ft then ramping up to 45-50kts by 20Z.

WAA from an approaching storm will start to create snow over
the western part of the state by 09-11Z in BFD and JST. The
snow will spread to the east, and get slightly heavier through
the morning. Flight conditions drop into IFR by 13-14Z in BFD
and JST, 16-18Z elsewhere - and stay down for the next 12-24hrs.

The center of the primary low pressure of this storm tracks over
KERI on Sunday. This path will ensure a ever-growing warm nose
aloft. There should be enough warm air aloft to turn the precip
to liquid before or right around sunset at JST and AOO, and at
most other terminals in Central PA by 01-02Z. But, it will be
FZRA/DZ for a period of 3-6hrs. Then, the above-freezing air
reaches the sfc overnight and almost everyone turns to plain
rain by 06Z. UNV and IPT will be the last to turn to RA, but
should do so well before sunrise. This warm up over the
snow/sleet on the ground will likely create widespread
(advection) fog and/or low stratus for later at night and
Sunday morning, which is why the IFR and LIFR will continue.

Cold air returns to BFD Sun aftn after the cold front passes. The
gusty NW wind will make some -SHSN off the lakes and with the
help of the upslope flow. These will last into Sun night for BFD
and Monday AM for JST where the IFR will last the longest.

Outlook...

Mon...Sub VFR cigs and SHSN JST (mainly AM). Gusty (G30-45KT)
northwest winds over all the airspace.

Mon night-Tue...Generally VFR and breezy. Isold SHSN vicinity
BFD.

Wed...Widespread snow possible, esp S.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 9 AM this morning to 9 AM EST
Sunday for PAZ004>006-010>012-017>019-037-041-042-045-046.
High Wind Watch from Sunday afternoon through Monday morning
for PAZ005-006-010>012-019-026>028-035>037-041-042-045-046-
049>053-056>059-063>066.
High Wind Watch from Sunday afternoon through Monday afternoon
for PAZ017-018-024-025-033-034.
Winter Weather Advisory from 9 AM this morning to midnight EST
tonight for PAZ024-025-033-034.
Winter Weather Advisory from 11 AM this morning to 1 AM EST
Sunday for PAZ026>028-035-036-056-063-064.
Flood Watch from late tonight through Sunday evening for
PAZ033.
Winter Weather Advisory from noon today to 1 AM EST Sunday for
PAZ049>053-057>059.

&&

$$

SYNOPSIS...DeVoir/Banghoff
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Fitzgerald
AVIATION...Dangelo/Bowen

NWS CTP Office Area Forecast Discussion