Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

650
FXUS61 KCTP 180219
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1019 PM EDT Sat May 17 2025

.SYNOPSIS...
Upper low spinning between Toronto and Ottawa Ontario will
will slide east tonight and Sunday. Much drier air will
gradually move down from the northwest, and provide a mainly dry
night and Sunday with only sprinkles or an isolated shower or
two. A warm front will try to move into PA on Tuesday and make
some showers. A wet pattern then lasts for at least Wed and
Thurs.

&&

.NEAR TERM /UNTIL 8 AM SUNDAY MORNING/...
A moderately breezy and cooler overnight is on tap with much
lower humidity (compared to the past few nights) as surface
dewpoints fall from the upper 50s across the Susquehanna Valley
and join the rest of the CWA in the mid to upper 40s by daybreak
Sunday.

Plenty of stratocu clouds will persist overnight (esp across the
northern and western mtns) as llvl moisture advects SE off the
Glakes. Expect the temps to stay up higher than otherwise would
be expected w/o the clouds. Just some scattered sprinkles or an
isold SHRA may linger across the NW half of the CWA overnight.

Low temps will vary from the upper 40s to low 50s across the
northern and western high terrain to the mid and upper 50s in
the southern valleys.

&&

.SHORT TERM /8 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Breezy and quite cool conditions (by late May standards) will
highlight our weather on Sunday, with mostly cloudy skies across
at least the Central and NW two thirds of the CWA, with some
breaks of sunshine expected across the Lower Susq Valley - near
and to the SE of the I-81 corridor.

A few sprinkles or even a stray, brief shower is possible on
Sunday across the Northern Mtns as a couple of spokes of vort
slide down on the NW flow behind the departing upper low.

High temps won`t be more than 6-7F warmer than morning lows on
Sunday across the NW and probably a 12-15F climb over the SE
zones (mainly thanks to the downslope flow) as 8H temps drop
back into the single digits from mid-teens on Sat.

Dry weather follows as the sfc ridge pokes in from the N
helping to lower PWAT values to around 0.8 of an inch on Sunday.

BKN stratocu clouds linger over the NW half of the CWA Sun and
for much of Sun night in the far NW Sun night. Mins Sun night
will dip near 40F in the cooler valleys of the NW, while the SE
half should stay in the 50s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
GEFS 850T anomaly shows a slight downward T trend for Monday
into Tuesday with neutral/warming and ridging aloft. This will
help day time temps reach the mid 60s to low 70s while allowing
for mainly clear and chilly conditions Monday night with a
potential for frost over central and northern PA as PWAT values
drop to around 1 sigma below normal - or 0.3 to 0.4 of an inch.

The wet and disturbed weather pattern makes a return for the
middle of the week. The mid to late week period is highlighted
by another fairly sharp trough axis moving across the region on
Wednesday- Thursday, preceded and accompanied by numerous
showers and a chance for afternoon TSRA. The trough will also
bring in notably cooler air for the second half of the work week
as both the GFS and EC are in fairly good agreement on yet
another closed low moving over or just to the north of PA
(though the EC is about 12 hours or so slower with this
feature). Expect highs for the end of the week to struggle to
reach the mid 60s across the southeast and remain in the upper
50s to the north.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
The main area of showers that has been moving through the region
today is now working its way through MDT and LNS and will be
east of the region by 03Z. Ceilings will remain VFR at all
Central PA airfields through the next few hours. Model RH
profiles suggest that MVFR ceilings will first develop at BFD
around 05Z, though there is around a 30% chance that they move
in an hour or two sooner. The low clouds will spread
southeastward into the early morning and there is a 50 to 70
percent chance that MVFR ceilings develop at all sites except
MDT and LNS by sunrise. Ceilings will fall to IFR at BFD and
remain there for much of the day on Sunday, while all other
sites see ceilings return to VFR by 15Z.

While most of the region will be dry during the day, a few
showers will be possible at BFD. Confidence on the timing of any
showers is low and will have to be adjusted with future TAF
issuances.

West-northwesterly wind gusts have decreased to 15 to 25 knots
and will likely remain in this range for much of the night
before increasing to 20 to 30 knots during the day. Model
soundings show 40 knot winds around 2000 feet across much of the
area tonight, but have held off on including LLWS in the TAFs
as surface winds should remain elevated enough to limit the
threat.

Outlook...

Mon-Tue...VFR.

Tue PM-Thu...Ocnl SHRA/TSRA.

&&

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

&&

$$

SYNOPSIS...Lambert/Dangelo
NEAR TERM...Lambert/Dangelo
SHORT TERM...Lambert/Dangelo
LONG TERM...Lambert/Bowen
AVIATION...Bauco