textproduct: State College

WHAT HAS CHANGED

* Dense Fog Advisory issued for the NW Alleghenies until 9AM * Odds for rain increased tonight (northern tier) and Friday * Odds for rain decreased/shifted to the south for the weekend * Increasing confidence in frost/freeze risk early next week

KEY MESSAGES

1) Quick turnaround to summerlike warmth to end September and start October

2) Showers expected Friday with cooler weekend forecast trending drier

3) Increasing confidence in frost/freeze risk early next week

DISCUSSION

KEY MESSAGE 1: Quick turnaround to summerlike warmth to end September and start October

A burst of summerlike conditions are expected to peak later this week as the calender flips from September to October. Fcst max temps on Thu/Fri in the 75-85F range are +10-15 degrees above the historical average and may be the warmest conditions observed for the remainder of 2026. For context, the average last date of max temp >=80F is 9/27 at State College, 9/29 at Altoona, 10/2 at Williamsport and 10/5 at Harrisburg.

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KEY MESSAGE 2: Showers expected Friday with cooler weekend forecast trending drier

Some light rain could brush the northern tier later tonight into early Thursday morning. The best odds for more widespread rain showers are now focused on the late Thursday night (NW) through Friday time window as a cold front moves southeastward from the eastern Great Lakes. Latest model data now in better agreement in suppressing rain chances farther to the south this weekend resulting in declining precip probs/increasing odds for a mainly dry first weekend of October.

Noticeably cooler and less humid air will filter into the region behind the front. 24hr maxT change on Saturday is fcst to be 10-15 degrees lower vs. Friday across south central PA with highs in the 60-70F range. The cooling trend continues through early next week with no rain forecast through Wednesday.

------------------------------------------------------------- KEY MESSAGE 3: Increasing confidence in frost/freeze risk early next week

Secondary shot of seasonably cool/Autumn air is fcst to arrive early next week in association with Canadian high pressure. The overall pattern and corresponding NBM temperatures are signaling an increased risk of frost/freeze conditions Monday and Tuesday night. Some locations in the central Alleghenies may observe the first frost/freeze of the season which is generally on par with climo.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Lower ceilings are sticking around longer than expected over the northern and western terminals with more moisture than expected present in the lower levels. BFD and JST are hanging onto MVFR cigs, but they should scatter to VFR within the next few hours. Dry surface conditions are expected to persist through the remainder of today before moderate warm advection associated with a shortwave tracking to our north into Thursday morning will support light rain developing over the northern half of the region after 00Z Thursday. As of now, it appears that rain could make it as far south as UNV, but confidence is highest in BFD and IPT seeing measurable precipitation. The rain should be pretty light and cloud bases don't look to get below 5000 feet, so expect mainly VFR conditions to continue. There remains a low probability (30-40%) of lower CIGS again Thursday morning in BFD and IPT as clouds persist, but VFR ceilings will be prevailing through tomorrow almost everywhere.

Outlook...

Thu...-SHRA possible, mainly over northern PA, with potential for localized AM mist/fog.

Thu Night - Fri...Cold FROPA with showers along the front. LLWS possible, especially northern and western TAF sites.

Sat-Sun...VFR favored behind the FROPA, with lower confidence across southern PA where lingering moisture may bring intervals of low ceilings (primarily MVFR). AM fog possible.

CLIMATE

Soggy September Soaker... September 2026 (MDT) precipitation rankings IPT: 11th wettest (6.84") MDT: 26th wettest (4.72") AOO: 9th wettest (5.58") BFD: 10th wettest (4.85") JST: 3rd wettest (7.31") *since 2000 STC: 6th wettest (7.90")

CTP WATCHES/WARNINGS/ADVISORIES

None.