Strong Storm System Brings Heavy Mountain Snow to the Sierra Nevada and Critical Fire Weather Conditions to the Plains

A Pacific storm system will continue to bring low elevation rain and mountain snow to much of the West through Wednesday, with heavy mountain snow expected in the higher elevations of the Sierra Nevada. This system will also bring strong winds to the Intermountain West, Rockies, and Plains, which will create Critical fire weather conditions for the High Plains. Read More >

Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.

771
FXUS61 KCTP 221018
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
618 AM EDT Wed Apr 22 2026

.WHAT HAS CHANGED...
* Lowered today`s temps a few degrees in the east and lowered
Thursday`s dewpoints slightly from NBM based on pattern and
collaboration.
* Upped PoPs for Sat (vs previous fcst) due to increased
confidence.

&&

.KEY MESSAGES...
1) Much warmer today and even warmer Thursday and Friday.
Numerous light showers this morning, many more on Friday.

2) Wet start to the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1: Much warmer today and even warmer Thursday and
Friday. Numerous light showers this morning, many more on
Friday.

A warm front over the state this morning will be followed by the
parent low pressure area as it drops southward. The low won`t
drop all the way through Central PA until late in the day. The
numerous, but light and disorganized showers will continue into
mid-morning as they move southward. The precip is progged to
dry up and may not amount to more than a sprinkle for folks S of
US Route 22 - other than the Laurel Highlands where it should
rain up to a quarter of an inch. Some clearing will try to
happen late morning/afternoon as the thickest clouds slide to
the south. Clouds could hang tough in the east, and have nudged
temps down a few degs in the Poconos and E of Lebanon and
Lancaster. Just enough forcing will remain and afternoon
instability and a weak enhancement to orographic forcing could
touch off isolated SHRA near and just N of State College and
Williamsport, which would drift SE if they do form. The wind
becomes northerly this evening after the low and it`s attendant
cold front (more like a dry line) pass. This should dry it out
again.

Thursday looks dry and much warmer, jumping about 10F over
today. Everyone but the far NErn mtns will be in the 70s. An
80F is not out of the question close to the MD border. This
warmth and associated deep mixing should help dewpoints/RHs get
a little lower than NBM guidance. Min RH should be close to 30
pct if not lower Thurs. NAM is an outlier with much higher
dewpoints and cloud cover and slightly cooler temps in the west.
Have discounted for now. The front that passes through late
today/early tonight will return northward over western PA on
Friday.

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

KEY MESSAGE 2: Wet start to the weekend.

The lift over the front and daytime instability will generate
sct SHRA/TSRA in the western half of the CWA on Friday. The
cold air tries to hang on over the east and may even back in a
bit as the upper low over New England presses southward along
the coast. This will keep the warm front in place or nudge it to
the west as a backdoor cold front. The energy diving down from
the N/NW and perhaps an enhanced LLJet will bring in more
moisture, and generate more SHRA/TSRA Fri night. Sat looks
pretty wet for everyone with numerous SHRA/TSRA. QPF in the
0.5-1.00" range is a solid forecast for many Fri night and Sat.
Some model divergence is seen for Sunday, though. Confidence is
low in how fast the precip moves through. So, Sunday may hold
sct SHRA, and PoPs in the 20-35% range are being kept for the
time being.

Next storm system approaches for Tues, resulting in a medium
confidence and medium to high PoPs. Will leave those high PoPs
in for now, but model/EPS difference exists on evolution of the
storm/mass fields.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
The timing/extent of lowering cloud ceilings has continued to
be delayed as dry antecedent air (T/Td spreads around 5-10
degrees C) has limited boundary layer saturation. The HRRR/RAP
models continue to be favored for timing vs. other guidance
(e.g. NAM/NAM3KM and LAMP, which have been lagging behind the
trend). As such, IFR mentions were removed at KBFD with LAMP
probabilities for IFR dropping below 30%, and with MVFR
prevailing at KBFD/KJST through 16Z-17Z Wednesday due to onshore
flow (KBFD) and upslope westerly winds (KJST). Otherwise,
scattered rain showers will continue to move eastward across
Central PA and exit our area through 16Z as a weak low pressure
moves across the region.

Prevailing VFR is likely (80-90% chance) after 18Z as W/NW
winds aloft advect drier air over the region. With that said, a
few showers may develop where the low pressure center passes
overhead in the afternoon, with a PROB30 for P6SM -SHRA included
at KIPT between 19Z-23Z based on HREF PoPs during that
timeframe.

Overnight (after 06Z), fog development becomes a concern due to
largely cloud-free skies and light winds, particularly across
the southeastern airfields (KMDT/KLNS). For KMDT/KLNS, light
easterly flow on the backside of the low pressure that brought
us rain showers earlier today will keep low-level moisture in
place, increasing the chances for visibility restrictions due to
mist/fog. Confidence for fog (around 30%) is higher at KLNS
given their proximity to the coast, with less confidence at
KMDT. Moreover, upslope winds at KJST may contribute to low
clouds developing after 06Z, with restrictions to IFR possible
(40% chance) at the site.

Outlook...

Thu...VFR. Partly cloudy and rainfree.

Fri...Light rain possible. VFR to MVFR.

Sat-Sun..Periods of rain with MVFR to IFR conditions.

&&

.CLIMATE...
A handful of record lows were set/tied on Tues morning (April
21st):

Harrisburg`s 29 broke the previous record of 30 degrees set
back in 1956.

Altoona`s 24 broke the previous record of 26 degrees also set
back in 1956.

Williamsport tied it`s record of 25 degrees set back in 1925.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

WHAT HAS CHANGED...Dangelo
KEY MESSAGES...Dangelo
DISCUSSION...Dangelo
AVIATION...Teare
CLIMATE...Dangelo/Beaty

Forecaster's
Discussion: