Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

953
FXUS61 KCTP 021113
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
713 AM EDT Mon Jun 2 2025

.SYNOPSIS...
* Dry weather expected through midweek with hazy sunshine from
  Canadian wildfires
* Turning increasingly warmer and more humid later this week as
  the pattern shifts into summer mode
* Showers and thunderstorms return to the forecast from Thursday
  into the first full weekend of June

&&

.NEAR TERM /THROUGH TONIGHT/...
Mainly clear and unseasonably chilly start to what is likely
the coldest morning until the Fall season. Several mesonet obs
in McKean, Elk, and Warren County (along with a few additional
well-known cold spots) have printed min temps in the 29-32F
range.

Fog in the river and stream valleys across the northwest
Alleghenies will dissipate this morning as temperatures warmup
quickly under hazy sunshine; this has also ended the frost
threat and the advisory was allowed to expire.

High pressure will provide the first of 3 dry days across CPA
with highs from the mid 60s over the northern and western
mountains to the low 70s elsewhere. HRRR vertically integrated
smoke suggests hazy sunshine throughout the day which should
lead to a vivid and vibrant sunset later this evening.

Mainly clear to partly cloudy and not as cold tonight with min
temps rising +10-20F night/night into the 45-55F range or +/- 3
degrees of early June climo.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Ridging at the surface and aloft migrating over CPA should
ensure two more dry days to round out the short term period
through midweek. We added haze to the wx grid on Tuesday based
on a blend of the HRRR near-sfc smoke density/vertically
integrated smoke and coordination with neighboring WFOs.

The pattern shifts into summer mode by Wednesday with broad SW
flow transporting very warm air and higher (60+) dewpoints into
CPA. While it`s not clear how much smoke may linger and
potentially shave off from daytime max temps, highs on
Wednesday are projected to reach the 80-90F range going full-
send on Summer. The heat and humidity may be somewhat impactful
(despite max heat index values only in the low 90s) given the
early season ramp up following a very wet and relatively cool
May; the lack of heat acclimation will also be a key factor. The
HeatRisk forecast peaks in the moderate level which would
support possible impacts in some health systems and heat-
sensitive industries.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
03Z Update: No significant changes to the extended forecast with
the evening update. Showers and thunderstorms return to the
forecast for the second half of the week.

Previous discussion...

High pressure begins to shift further east Thursday
morning with model guidance outlining modest agreement in a weak
area of low pressure west of the area gradually moving closer
to central Pennsylvania. Surging PWATs and lowering heights
ahead of this area of low-pressure support precipitation
mentions just ahead of sunrise on Thursday. As low-pressure
approaches and better moisture spreads into the area Thursday
afternoon, widespread rain showers appear increasingly likely on
Friday as an associated cold front approaches the area. Cold
front is expected to be beginning to decay at this juncture with
lower shear values and marginal CAPE. Given these parameters,
low confidence on any severe weather concerns on Thursday.

Confidence in the forecast becomes lower after Friday; however,
with ECMWF deterministic guidance indicating drier conditions
early Saturday through the end of the long-term forecast period.
Recent GFS deterministic guidance does hold moisture further
into central Pennsylvania for the first half of Saturday before
trending drier through the end of period. Given this guidance,
have opted to stick close to NBM guidance Saturday and Sunday;
however, in future cycles could realistically see Sunday
trending drier overall.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
High pressure will provide the region with mainly clear skies,
dry weather, and VFR conditions into Tuesday and Wednesday. A
few high clouds are around to start the morning today, and we
could see scattered high clouds moving across central PA this
afternoon, otherwise it will be mostly clear.

A plume of Canadian wildfire smoke will be injected into the
upper atmosphere over the Pennsylvania airspace this evening and
into Tuesday. So far there has not been any surface level
impacts from the smoke, mainly just hazy skies. Additional
mixing on Tuesday could bring smoke lower into the atmosphere,
but surface impacts still remain unlikely.

Outlook...

Tue-Wed...VFR expected.

Thu...Potential brief restrictions in SHRA/TSRA NW.

Fri...Numerous SHRA/TSRA, esp NW. Brief reductions to MVFR and
IFR in the TSRA.

&&

.CLIMATE...
May 2025 Precipitation Rankings

Site                           2025 | Wettest May on Record
-----------------------------------------------------------
 Harrisburg*         10.02" Wettest | 9.71" in 1989 (previous)
 Williamsport     7.18" 7th Wettest | 9.91" in 1919
 Altoona*             7.34" Wettest | 7.31" in 1960 (previous)
 State College  7.56" T-7th Wettest | 9.45" in 1894

(* denotes that May 2025 set a new record in precipitation in
their respective locations. The previous record remains listed
under the "Wettest May on Record" column.)

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Bauco/NPB
AVIATION...Bowen
CLIMATE...NPB