textproduct: State College

WHAT HAS CHANGED

* Added discussion about possible snow Sunday night into Monday.

KEY MESSAGES

1) A few showers to linger into this afternoon.

2) Snow possible tonight into Monday morning as colder air settles in.

3) Freeze potential across northern/western Pennsylvania tonight into Monday morning. Widespread damaging frost/freeze threat extends across all of central Pennsylvania Monday night into Tuesday morning.

4) Drier conditions in the early to middle part of the week may result in a marginal increase in risk of wildfire spread.

DISCUSSION

KEY MESSAGE 1: A few showers to linger into this afternoon.

Some showers this afternoon, mainly across the east, just behind the cold front.

Cooling aloft with some afternoon heating has resulted in some showers across the far west over the mountains. Time of day should keep most everything in the form of rain.

In addition, winds not that strong yet, dewpoints still mainly in the 30s. Monday will have a much different feel to it.

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KEY MESSAGE 2: Snow possible tonight as colder air settles in.

Cooling aloft and a secondary cold front will result in some late season snow showers across the north and west.

Most of the snow will be over with shortly after sunrise on Monday, as much drier air is advected into central PA. Amounts will be mainly a dusting to an inch over the higher hilltops.

Cooling aloft could result in a heavier squall early Monday, as we get some heating, but the advection of very dry air will likely offset the cooling aloft, thus think squall potential remains low.

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KEY MESSAGE 3: Freeze potential across northern/western Pennsylvania tonight into Monday morning. Widespread damaging frost/freeze threat extends across all of central Pennsylvania Monday night into Tuesday morning.

Confidence is /very/ high in a widespread freeze Monday night/Tues morning due to a combination of high pressure nearby, light wind, and 8H temps in the -5 to -10C range overhead.

The setup for tonight is a bit less favorable, which means freezing temperatures are unlikely southeast of the I-99/I-80 corridor. Farther west and north, a Freeze Warning is now in effect. Despite lows in the middle 30s for the rest of the CWA, sufficient winds and some cloud cover will limit the potential for frost, thus precluding any Frost Advisory issuance.

The growing season has been activated for all but four zones (Tioga/Sullivan/Potter Counties and Northern Lycoming County) across central Pennsylvania as of 04/18/2026, see the latest Public Info Statement for those details.

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KEY MESSAGE 4: Drier conditions in the early to middle part of the week may result in a marginal increase in risk of wildfire spread.

Monday will see lower dewpoints work into the area, as any showers taper off. Also gusty winds pick up during the day.

Relative humidities dip down closer to the ~30% critical threshold with Monday outlining the best potential for some post-frontal gusty winds. With rainfall and cooler temperatures, this may limit the risk of fire concerns.

Tuesday will trend warmer with slightly lower RH values, but winds are not expected to be quite as gusty.

AVIATION /00Z MONDAY THROUGH FRIDAY/

A shortwave trough will cross the Commonwealth tonight, with increasing clouds (mainly VFR) and spotty rain/snow showers on tap for the night. Flight restrictions to MVFR are moderately likely (40-60% chance) over the Northern Tier (KBFD) and Allegheny Front (KJST) between 05Z-10Z Monday as the shortwave passes overhead, with VFR likely (70-80% chance) to prevail thereafter. Scattered snow showers associated with this shortwave are expected to move over the sites between 02Z-10Z Monday, with rain/snow showers preferred across our central sites (KAOO/KUNV/KIPT) during that timeframe. Prevailing flight restrictions appear unlikely across our sites at this time, though TEMPO groups may be needed at KBFD/KJST if any organized snow showers develop.

From 12Z Monday to the end of the TAF period, VFR is very likely (80-90% chance) to prevail across Central PA, with northwesterly winds gusting to 20-25 kts expected. Given steep low-level lapse rates in place (9.8 C/km in the lowest 2 km) and upslope/offshore flow, a few spotty rain/snow showers may develop across the region (primarily KBFD/KJST/KIPT). Flight restrictions seem unlikely with these showers, similar to how Sunday's rain/snow showers evolved.

Outlook...

Tue AM...Dry with VFR conditions expected.

Tue PM-Wed AM...Scattered -SHRA possible.

Wed PM-Thu...Drying trend with VFR conditions.

Fri...Dry with VFR early, increasing chances of -SHRA by the afternoon and evening hours.

CTP WATCHES/WARNINGS/ADVISORIES

Freeze Warning from midnight tonight to 9 AM EDT Monday for PAZ004-005-010>012-017>019-024-025-033-034-045-046. Freeze Watch from late Monday night through Tuesday morning for PAZ004-005-010>012-017-018. Freeze Watch from late Monday night through Tuesday morning for PAZ019-024>028-033>036-045-046-049>053-056>059-063>066.