NWS Forecast Discussion
527
FXUS61 KCTP 171000
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
600 AM EDT Fri Apr 17 2026
.WHAT HAS CHANGED...
* Slight Risk of severe weather west of US-219 on Saturday
afternoon.
* Increasing confidence in damaging frost/freeze Monday &
Tuesday morning.
&&
.KEY MESSAGES...
1) Slightly cooler but still much warmer than average today and
Saturday.
2) A cold front will bring showers and thunderstorms (some could
be severe in western PA) and a break from summer heat late this
weekend.
3) A damaging frost/freeze is likely Monday and Tuesday morning.
&&
.DISCUSSION...
KEY MESSAGE 1: Slightly cooler but still much warmer than average
today and Saturday.
A moisture-deprived cold front will cross the region today and knock
temps down 5-10 degrees compared to yesterday. Even still,
temperatures will be +10 to +15 compared to average. Today will
be rain-free for most with a mix of sun and clouds. Temperatures
will trend a bit warmer again on Saturday as southerly flow
increases ahead of an approaching cold front. South winds could
gust 20 to 30mph ahead of the front on Saturday afternoon.
-----------------------------------------------
KEY MESSAGE 2: A cold front will bring showers and thunderstorms
(some could be severe in western PA) and a break from summer
heat late this weekend.
The next round of showers and storms will come ahead of a cold
front Saturday afternoon and evening. SPC has introduced a SLGT
severe weather outlook for eastern OH and western PA Saturday,
with the MRGL risk area extending east to the I-99 corridor. A
mid-level trough will drift across the Great Lakes and help
generate sufficient instability and shear for severe weather.
There remains some question as to how much moisture will be in
place ahead of the front, especially east of the Allegheny
Front. If dewpoints trend above 60F, the risk for severe weather
could further increase. Damaging straight line wind gusts
appear to be the primary threat, but if any discrete cells can
form and avoid upscale growth, the risk for tornadoes and/or
hail would be locally enhanced.
After the initial batch of storms moves through, a secondary
area of stratiform rain showers is likely along the surface
front overnight Saturday. A few snow flakes could even mix in
along the northern tier as colder air races in. The cold front
should pretty much clear southeast PA by 8AM Sunday morning, but
lingering showers are expected through at least midday Sunday
for southeast PA.
-----------------------------------------------
KEY MESSAGE 3: A damaging frost/freeze is likely Monday and
Tuesday morning.
The significant cold front ushers in much, much colder air
beginning Saturday night. In fact, there could even be some
snow showers on Sunday. While it will be getting near freezing
in the NW half of the CWA Sunday night/Mon AM, Sunday night may
be too windy for frost to form. Some places will get down to
freezing, which will necessitate a Freeze Warning being issued
at some point. The most certain time frame for sub- freezing
temps is Monday night/Tuesday AM. On Monday morning, freezing
temperatures are most likely along, north, and west of the
I-99/I-80 corridor. On Tuesday morning, freezing conditions are
favored down to the I-81 corridor with frost conditions
southeast of there.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Northwesterly offshore flow will transport low-level moisture
from Lake Erie to the Northern Tier (KBFD) and Laurel Highlands
(KJST) late tonight. At KBFD, the LAMP suggests a moderate to
high (60-80%) chance of MVFR ceilings through 18Z, with IFR
being moderately likely (30-50% chance) between 07Z-15Z.
Moreover, there is a low chance (10-20%) of LIFR per the LAMP,
though upstream observations will need to be monitored to
increase confidence. Further south at KJST, MVFR ceilings are
moderately likely (40-60% chance) primarily between 11Z-17Z as
winds shift northwesterly. A SCT025 layer was added between
02Z-11Z is to hint at a low chance (10-20%) of MVFR ceilings due
to upslope showers, though certainty is too low to prevail
MVFR.
In the morning and early afternoon on Friday, a 850 mb
temperature minimum associated with the trough will be passing
overhead, which when combined with daytime heating and
sufficient moisture with dew points in the 50s, spotty showers
are possible. This possibility was reflected by PROB30s at
KAOO/KUNV/KMDT/KLNS where the HREF had 30% PoPs between 14Z-15Z
and 18Z. After 18Z, VFR is highly likely (80-90% chance) to
prevail due to subsidence on the backside of this shortwave,
with drier air filtering in from the north.
Outlook...
Sat-Sun...Restrictions in SHRA possible, transition to SHSN
across higher elevations overnight Sunday night into Monday
morning.
Mon...Lingering SHSN possible early across N PA with
restrictions possible; otherwise, dry conditions with VFR
prevailing.
Tue...Dry with VFR conditions prevailing early, rain showers
move south-to-north across the area during the afternoon and
evening hours.
&&
.CLIMATE...
DATE 4/15 4/16
LOW HIGH LOW HIGH
Harrisburg 87=
State College 61
Williamsport 58 87 59 90=
=Temperature ties the previous record
Record high daily mins are possible again today.
Here`s a look at the records as they stand right now, with a *
indicating that the forecast is equal to or greater than the
record.
Record High Daily Max / Daily Min...
For Harrisburg:
April 17: 91 (2002) / 60* (2002)
For Williamsport:
April 17: 91 (2002) / 58* (1896)
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
WHAT HAS CHANGED...Banghoff
KEY MESSAGES...Lambert/Banghoff
DISCUSSION...Lambert/Banghoff
AVIATION...Teare/RXR
CLIMATE...Colbert
NWS CTP Office Area Forecast Discussion
