Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

788
FXUS61 KCTP 250152
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
952 PM EDT Sun May 24 2026

.WHAT HAS CHANGED...
* Slight increase in rainfall amounts, mainly across
  northwestern Pennsylvania overnight into Monday morning.
* Slight decrease in eastward extent of the thunderstorm
  potential this evening.
* Dense fog advisory until 10 AM for Schuylkill Co.

&&

.KEY MESSAGES...
1) Widespread rain across central Pennsylvania later Sunday
evening through Memorial Day morning.

2) Warmer midweek with scattered showers before a cooler and
brighter end of May.

3) Areas of low clouds and fog overnight.

&&

.DISCUSSION...
KEY MESSAGE 1: Widespread rain across central Pennsylvania
later Sunday evening through Memorial Day morning.

Current radar outlines some showers across southwestern
Pennsylvania this (Sunday) afternoon, which are expected to
continue tracking northeast, with more robust rainfall stationed
across the Mid-to-Lower Ohio River Valley. An upper-level
disturbance will continue to swing through the area tonight,
with an additional round of showers expected overnight and into
Monday morning. Current forecast does bring this initial round
of showers with a two-three hour lull before the more widespread
rainfall starts for the evening. Recent HREF model guidance
brought a signal for locally heavier rainfall northwest of the
Pittsburgh metro area) and does touch our some of our western
zones in Elk/Cameron counties, where a swath of 2-3" PMMs has
been observed in the 12Z HREF run. These areas have avoided much
of the heavier rainfall over the past couple of days, thus not
a lot of large- scale flooding concerns. WPC did maintain a
Marginal Risk for Excessive Rainfall across Cambria/Somerset
counties this evening, mainly due to some convective elements;
however, generally expect the flooding concern here to be very
isolated with no large-scale concerns. Further southeast,
ongoing drought conditions and lower rainfall totals provide
zero flooding threat with this rainfall.

Guidance continues to depicts a cold front dropping southeast
through the Commonwealth on Memorial Day with dry air behind
the frontal passage bringing an end to the showers. Rain will
likely linger in the southeast into the mid afternoon, but a
drying/brightening trend can be expected in the northwest.
Building surface high pressure also means the stubborn cloud
cover will finally mix out/collapse Monday evening across the
north. A few peeks of sun could even make an appearance at
Memorial Day cookouts across the northern tier. Highs trend much
warmer on Monday, generally in the 70s everywhere.

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

KEY MESSAGE 2: Warmer midweek with scattered showers before a
cooler and brighter end of May.

Clearing skies across the north on Monday night in the presence
of wet ground will likely to fairly widespread fog formation
into Tuesday morning. Many models depict high probabilities in
reduced visibility, especially north and west of the I-81
corridor. Dense Fog Advisories may be needed; however confidence
remains low at this juncture.

Monday`s warming trend will continues into the middle of the
week, with highs expected to be in the upper 70s and low 80s by
Wednesday. The cold front that moves through PA on Monday will
stall out across KY/WV/VA for the middle of the week. This could
keep some daily shower/thunderstorm chances in place across the
southern tier of PA along with more widespread cloud cover
there. Wednesday looks like the best chance for storms at this
point.

A reinforcing ridge of high pressure will push another cold
front through the Commonwealth on Thursday. Behind it, cooler
temperatures and brighter skies will follow. High pressure
should ensure a much more pleasant last weekend of May than
we`ve had this Memorial Day weekend. Lows in the 40s to 50s and
highs in the 60s to 70s will be within a few degrees of average
conditions this time of year. It will be a great weekend for
planting flowers if you haven`t gotten anything in the ground
yet!

___

KEY MESSAGE 3: Areas of low clouds and fog overnight.

Unlike the last 2 nights, lower clouds down to top of the
hilltops in spots, especially northeast of MDT, along interstate
81. Not seeing much change in conditions across Schuylkill Co.
before morning, so issued a dense fog advisory until 10 AM.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Conditions have deteriorated in the past few hours with several
sites trending from MVFR to IFR, and even a brief period of
LIFR cigs already observed at JST around 00z. Steady light to
moderate rain has overspread west-central PA and will continue
to spread eastward through the overnight, although the intensity
will likely trend downward with eastward extent. Nonzero chances
for LIFR cigs/vsby at all airfields, but the highest chances
are BFD/JST/MDT/LNS (30-60 pct chc, peaking in the predawn and
early morning hours).

The back edge of the rain, seen moving east of Erie at 0130z,
will likely be near JST/AOO/UNV/IPT around 12z Mon, but will
slow as it approaches MDT/LNS, keeping a chance of stray
-SHRA/TSRA in the forecast through the early evening Mon.

As the rain moves out, any remaining LIFR will give way to IFR
in the morning, trending toward MVFR by 15-18z, with VFR
possible at all airfields by 18-23z Mon as winds switch to NW
and advect drier air.

Outlook...

Tue...Possible morning fog, then VFR.

Wed...Mainly VFR, some scattered SHRA could bring restrictions.

Thu-Fri...Mainly VFR, skies mostly clear

&&

.CLIMATE...
Several daily record low maximum temperatures were set or tied on
Saturday May 23:

LOCATION      OBSERVED HIGH   PREVIOUS RECORD (YEAR)
Harrisburg          54             54 (1982)
Williamsport        54             57 (1982)
Altoona             50             52 (2005)
State College       51             53 (1968)

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EDT Monday for PAZ058.

&&

$$

WHAT HAS CHANGED...Colbert/Martin/Beaty
KEY MESSAGES...Colbert/Martin/Beaty
DISCUSSION...Colbert/Martin/Beaty
AVIATION...Colbert/Lambrech
CLIMATE...Banghoff/Beaty