textproduct: State College

WHAT HAS CHANGED

* No significant changes

KEY MESSAGES

1) Improving conditions late today with noticeable warmup and several days of dry conditions to end September and start October

2) Cooling trend this weekend into early next week with an increasing chance of rain Saturday and Sunday.

DISCUSSION

KEY MESSAGE 1: Improving conditions late today with noticeable warmup and several days of dry conditions to end September and start October

850-700 mb thermal trough over the CWA this afternoon morning will be exiting stage right tonight, allowing the cloud depth to shrink with gradual clearing early tonight as deep-layer subsidence and slightly lower PWAT air advecting in from the west.

Temps +5-10 degrees warmer vs. Monday are near their max values this mid afternoon hour...in the 65-75F range.

Less cloud cover and light wind tonight will favor strong radiational cooling of the ground and locally dense valley fog will form with very low visibility restrictions into early Wednesday morning.

A continue warmup will extend through the mid to late week period with fcst max temps in the 75-85F range or +10-15 degrees above the historical normal for the end of September/beginning of October.

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.

No rainfall is forecast through Thursday with some showers possible on Friday-Friday night associated with cold front sinking southeastward from the eastern Great Lakes. --------------------------------------------------------------- KEY MESSAGE 2: Cooling trend this weekend into early next week with an increasing chance of rain Saturday and Sunday.

24hr maxT change on Saturday behind the cold front is fcst to be 10-15 degrees lower vs. Friday with highs in the low 60s/70s. Trailing frontal wave could bring more widespread soaking rain on Sunday based on WPC/NBM QPF - although EC/CMC and (to lesser extent) lean farther to the south/east with the frontal precip. Confidence is higher that temps continue to cool off and drop near or below the historical average into early next week. Frost potential is on the table for next Monday and Tuesday night.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

MVFR ceilings are currently being observed across most of central PA this afternoon with the exception of LNS and MDT where they are in VFR. Ceilings will continue to rise this afternoon with VFR conditions developing. Breaks in the clouds should promote fog formation tonight with widespread visibility restrictions into Wednesday morning. For locations further south and east, clouds could linger for a portion of the overnight period which would lead to lower fog probabilities at MDT and LNS.

Across northwestern PA, there is higher confidence of fog development due to quicker cloud erosion this evening compared to areas further south where there will be lower fog chances. For areas that see fog, IFR conditions are likely. BFD, UNV, and IPT may additionally see a period of VLIFR conditions closer to sunrise due to amble low level moisture in most recent RAP soundings at those locations. After sunrise, fog will mix out quickly leading to widespread VFR conditions across central PA.

Outlook...

Thu...Chance of showers late PM, some restrictions possible.

Fri...Cold FROPA with showers along the front.

Sat-Sun...Uncertainty abounds, rain/lower cigs possible south, brighter/less restrictions north.

CLIMATE

Soggy September Soaker... September 2026 (MTD) 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.