Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

078
FXUS61 KCTP 300601
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
201 AM EDT Mon Jun 30 2025

.SYNOPSIS...
* Mainly clear to partly cloudy night with patchy valley fog
  possible across CPA.
* Stormy pattern resumes Monday-Tuesday with a renewed risk of
  strong to severe storms and locally heavy downpours
* Drier/less humid/more comfortable conditions are likely
  through midweek with high confidence of nice wx on the 4th

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
Showers and storms have struggled to make it across the MD
boarder this afternoon, leaving the area with mostly clear skies
heading into this evening.

Any lingering Cu will fade as the sun sets with a mainly clear
to partly cloudy night ahead. There will be some fog in the
valleys from the predawn hours through daybreak Monday. Fog may
be limited to some extent by increasing mid and high clouds as
WAA pattern ramps up over the Ohio Valley downstream of 500mb
trough moving into the Upper Midwest. Lows tonight will feel
similar to last night with near 70F likely across the Lower
Susquehanna Valley to low 60s in the north.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH TUESDAY NIGHT/...
*Stormy End to June/Start of July moving into the 2H of 2025

A mid-level trough will amplify while traversing the Great
Lakes and Ohio Valley regions on Monday. A cold front will
accompany the Midwest mid-level trough and should reach western
PA by 12Z Tuesday.

In advance of the cold front, plenty of moisture/instability
will be present to support at least scattered thunderstorms by
peak heating. Given the presence of weak/modest vertical wind
shear, a few of the storms could become strong to locally
severe. Strong boundary-layer heating is fcst with 2000+ J/kg
of tall/thin SBCAPE) amid weak (<30kt) 0-6km deep layer wind
shear. This environment will support wet downburst potential
and a couple of damaging wind gusts are possible Monday
afternoon and evening. SPC has all of CPA in a level 1/5 MRGL
svr tstm risk for D2.

The aforementioned mid-level trough will shift east from the
Great Lakes to the Northeast on Tuesday. Moderate mid-level flow
will overspread much of the region. At the surface, a cold
front will move east across PA and will be the primary focus
for severe thunderstorm potential Tuesday afternoon/evening.

Stronger shear profiles will be present on D3 and this may
result in greater storm organization/intensity including the
potential for a few supercells capable of producing large hail
and damaging wind gusts. SPC will expand the level 1 MRGL svr
risk for D3, but we would not be surprised to see an future
upgrade to SLGT or level 2/5 given the more robust shear
profiles.

Max/min temps will be seasonably warm/muggy for late June and
early July in the 80-90/60-70F range to start the week. Temps
will cool off a bit on Tuesday/Tuesday night behind the front
over the north/west Alleghenies.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
* Expect a drier and more comfortable stretch of weather for
  Wed-Sat.
* Increasing confidence in nice/dry weather on July 4th.

There is growing confidence in a drier and more comfortable
stretch of weather from midweek into the first weekend of July.
Expanding on the drier/comfortable stretch, we are talking
specifically about: 1) little to no rainfall and 2) noticeably
lower heat and humidity.

A moisture-starved cold front will provide the "best" chance of
rain Thursday PM, but overall we expect the majority of the
time to be dry during the Wed-Sat period.

Max/min temps will be close to the historical average during
the first week of July. There are signals for heat and humidity
to ramp upward by the end of the weekend.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Lone shower in south central PA died shortly after Midnight.
However the edge of the higher dewpts not much further south
and also to our west, once one gets into OH.

NAM shows showers and storms will try to work in from both
the southeast and west toward mid to late aft. Highest chc
of thunder will be mainly west of a BFD, JST line.

Did not make any big changes to the earlier TAF fcst.

CIGS likely to be rather high with showers and storms this
afternoon, but would would lower down by mid to late evening.

Earlier discussion below.

Predominantly VFR conds are expected to continue overnight,
although there is low confidence that some spots could see the
development of fog/low clouds during the predawn hours. High
and mid level clouds may help to limit fog development.

Scattered SHRA/TSRA impacts are expected Monday afternoon and
evening, and have added a PROB30 group to several TAF sites Mon
aftn/eve to highlight the potential for brief restrictions.

Outlook...

Mon-Tue...PM showers & t-storms likely; areas of fog & low
clouds overnight.

Wed...AM fog, then VFR.

Thu...Primarily VFR; stray PM shower/t-storm possible.

Fri...AM fog possible; otherwise VFR.

&&

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

&&

$$

SYNOPSIS...Steinbugl/Bowen
NEAR TERM...Steinbugl/Bowen
SHORT TERM...Steinbugl
LONG TERM...Steinbugl/Evanego
AVIATION...Martin/Evanego