862 FXUS61 KCTP 291043 AFDCTPArea Forecast Discussion National Weather Service State College PA 643 AM EDT Mon Sep 29 2025
.SYNOPSIS... * Very warm to close out September; cool down to start October * Frost risk focused across the northern tier Wednesday night * Dry/parched pattern stays locked in place for the 7-10 days
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.NEAR TERM /THROUGH TONIGHT/... Early morning IR satellite shows valley fog across the NW 1/2 of the CWA where skies are clear. HREF data shows high clouds across the SE 1/2 of the fcst area overspreading all of CPA by early afternoon. Despite a partly sunny to mostly cloudy day on balance, it will be very warm for the end of September with max temps in the 75-80F range or +7-15 degrees above the historical average.
Canopy of mid and high cloud cover should limit fog formation tonight into early Tuesday morning. Another relatively mild night vs. climo (+5-10F) with lows generally in the upper 40s NW to low 60s SE.
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.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... September ends very mild with max temps fcst in the 70-80F range. Shield of mid and high clouds are projected to gradually clear from NW to SE through Tuesday night. Backdoor cold frontal passage later Tuesday will open the door for seasonably cooler and drier air to filter into CPA behind a steady breeze from the N/NE. Low temps Tuesday night will be 5-10 degrees lower vs. Monday night ranging from the upper 30s in the northern tier to low 50s in the Lower Susquehanna Valley.
October will start with seasonably strong 1030+mb Canadian HP migrating southeast from Hudson/James Bay into northern New England. The cooler and drier llvl flow from the N/NE will bring a noticeable cool down through midweek with highs on Wednesday 5-10 degrees lower vs. Tuesday in the low 60s/70s.
Clear and cool Wednesday night; high confidence in frost risk across the northern tier with decreasing wind and min temps in the mid 30s.
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.LONG TERM /THURSDAY THROUGH SUNDAY/... Slow moving and blocky pattern under deep layer ridging over the Mid Atlantic and Northeast states will lock-in the renewed run of dry wx through the first weekend of October. NBM/WPC QPF is 0.00" in CPA for the next 7+ days.
Thursday night also looks chilly with some frost possible again over the northern tier; otherwise look for max/min temps to rebound (day over day) with larger departures from climo on daytime highs vs. nighttime lows (which is largely a function of the dry/low Td air remaining in place).
The return of the multi-day/persistent parched pattern could offset any short term improvement in the low-end drought conditions from much needed/beneficial rainfall last week.
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.AVIATION /12Z MONDAY THROUGH FRIDAY/... Pockets of valley fog have developed overnight, but this fog remains patchy and has had no impacts to TAF sites as of this morning. Any lingering fog will dissipate over the next hour or so, and we should be in for another day of widespread VFR conditions today. High clouds will build in, and we should see bkn or ovc skies by this afternoon due to tropical influence to the south. No precipitation or reduction in flight categories is expected however. Winds will again be relatively light, generally less than 5 kts.
Outlook...
Tue...Patchy AM fog. Otherwise, predominantly VFR.
Wed-Sat...Predominantly VFR.
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.CTP WATCHES/WARNINGS/ADVISORIES... None.
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SYNOPSIS...Steinbugl NEAR TERM...Steinbugl SHORT TERM...Steinbugl LONG TERM...Steinbugl AVIATION...Bowen
NWS CTP Office Area Forecast Discussion