textproduct: State College

WHAT HAS CHANGED

* Frost Advisory expanded and Freeze Warning issued for the western Alleghenies and northern mountains late tonight into early Friday morning

KEY MESSAGES

1) Cool and unsettled pattern to end April and start May with shower chances and frost/freeze risk through the weekend

DISCUSSION

KEY MESSAGE 1: Cool and unsettled pattern to end April and start May with shower chances and frost/freeze risk through the weekend

Several disturbances rotating around a persistent upper level closed low centered over Ontario and Quebec will help to reinforce broadly deep troughing across the eastern U.S. through much of next week. This pattern will keep conditions cool and unsettled at times as multiple frontal systems move through. In addition to shower chances, the fronts will bring reinforcing surges of cool air, keeping temperatures near to below seasonal averages. Chilly nighttime lows will also lead to frost and freeze concerns Thursday-Saturday night, particularly now that the growing season is now active across all CPA zones.

Upper level flow briefly becomes more zonal tonight and weak ridging develops below 700 mb behind a disturbance bringing scattered showers to the region this afternoon, which should help to clear out much of the cloud cover over the region. This combined with light winds should be supportive of radiational cooling and temperatures should fall into the 30s across all of central PA. While there could still be a few clouds over the northwest, confidence in frost and freeze conditions has increased. As a result, the Frost Advisory has been expanded a tier of counties to the east, and was upgraded to a Freeze Warning for Elk, McKean, and Potter Counties.

The next shortwave rotating through the broad upper trough will bring a round of showers to the region during the day tomorrow, but we again expect to see enough clearing overnight for frost and freeze concerns to develop. The coldest night across northern and western parts of the forecast area will be Saturday night with a freeze almost certain, but there is some uncertainty regarding the southeastward extent of frost as there will be a rather tight pressure gradient across the region due to a developing area of low pressure off of the coast.

Temperatures trend warmer for the beginning of next week, but all guidance indicates that unsettled weather will continue with multiple chances for rain.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

A batch of rain showers will move across the region this afternoon, though no visibility restrictions are expected. As the transition to the deepening, cool NW flow occurs today, we'll see the typical lower conditions (IFR to low end MVFR) at KBFD and KJST while mainly VFR cigs will be seen elsewhere.

Winds will continue to be moderately gusty (high teens to low 20s (KTS)) this afternoon as high pressure builds east town the area in the wake of the departing low. Skies will clear tonight with winds calming down. Patchy fog is possible across the northern tier and could bring restrictions to BFD.

Another round of rain will move across the area on Friday, with accompanying MVFR ceilings expected at BFD and possible (30%) at IPT, UNV, JST, and AOO.

Outlook...

Fri-Sat...Mainly VFR with brief restrictions possible in showers.

Sun...Restrictions possible northwest in -RA and possibly some -SN.

Mon... Models hinting at another low pressure wave to our west, precip may lead to restrictions, particularly in the west.

CLIMATE

*Daily record rainfall of 1.18 inches at KJST yesterday 4/29 breaking the previous record of 1.13 inches set back in 1964 *Despite a cool end to the month, April 2026 will end as one of the warmest on record

CTP WATCHES/WARNINGS/ADVISORIES

Frost Advisory from midnight tonight to 8 AM EDT Friday for PAZ004-011-012-017>019-024-025-033-034-037-041-042-045-046. Freeze Warning from midnight tonight to 8 AM EDT Friday for PAZ005-006-010.