textproduct: State College

SYNOPSIS

* Blocky/slow moving seasonal transition pattern will continue the extended run of abnormally dry weather in central PA through the last week of astronomical summer

NEAR TERM /THROUGH TONIGHT/

Predawn/post-sunrise valley fog (concentrated in the northern tier river/stream valleys) will give way to a mix of low level fair wx cu and high cirrus by the afternoon with max temps +5-10F above the historical avg in the mid 70s to low 80s.

Despite high clouds, valley fog is still a good bet again tonight particularly across the northern tier. Low temps are near to slightly above mid September climo in the upper 40s to upper 50s.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Low pressure will lift slowly northward from the Outer Banks and VA Tidewater off the Mid Atlantic coast through midweek. Latest model data continues to indicate the best chance for rain over the southeast zones (southeast of I-81/78) where a moist/upslope easterly low level flow will deliver higher pwat air. 48hr QPF ending 12Z Thu ranges from <0.10 up to 0.50" within a tight NW- SE gradient across the lower Susq Valley with max amounts along the MD line to the north of Chesapeake Bay. Locations along and north/west of the US220/I99 corridor are not expected to see any rainfall which could manifest. The most noteworthy changes in sensible wx will be more clouds/less sunshine and a daytime cooling trend (lower highs) that will be more pronounced over the southeast half of the CWA.

LONG TERM /THURSDAY THROUGH SUNDAY/

A brief spell of dry conditions is once again expected in the wake of the coastal low, with moderate-to-high confidence in dry conditions on Friday. Recent model guidance has slightly slowed down with respect to the low pressure system in the Midwest with a fair amount of uncertainty between deterministic model guidance. Given these changes, have decided to roll with NBM through Sunday, with the best chances of precipitation coming after sunrise on Sunday.

AVIATION /11Z MONDAY THROUGH FRIDAY/

Fog will dissipate by 14Z, giving way to VFR conditions with varying amounts of high clouds as a coastal low well to our southeast slowly moves northward. The greatest amount of cloud cover will be over the southeast, while areas north of I-80 may see mainly clear skies for much of the day.

The clouds will decrease in coverage after 03Z, allowing for valley fog formation. The fog footprint will look similar to this morning, with the best chance of IFR conditions at BFD and IPT, though LNS likely has a lower chance of seeing fog as some high clouds will remain overhead. A few showers may try to enter southeastern PA towards sunrise, but the better chance looks to be after 12Z.

Outlook...

Tue...VFR with AM valley fog. Isolated SHRA possible late for SE PA.

Wed-Thu...Generally VFR, some SHRA possible (20-40%) SE PA.

Fri...VFR with AM valley fog.

CLIMATE

Astronomical fall officially begins with the autumnal equinox on Monday, September 22, 2025 @ 2:19 p.m. EDT. The Autumn 2025 season will last 89 days, 20 hours, and 43 minutes. Daylight saving time will end just after Halloween with clocks falling back at 2 a.m. Sunday, November 2, 2025.

CTP WATCHES/WARNINGS/ADVISORIES

None.