textproduct: State College

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Unsettled pattern for the upcoming week with multiple systems forecasted to move through the Commonwealth

2) Big temperature swing forecast for the week ahead

DISCUSSION

KEY MESSAGE 1: Unsettled pattern for the upcoming week with multiple systems forecasted to move through the Commonwealth

Improving weather conditions can be expected today as the remnants of Isaias exit the Mid Atlantic. Rain and isolated thunderstorm chances on Tuesday appear to be maximized over the northern tier where a shortwave aloft and sfc cold front (infused with moisture from TS Rachel?) streak eastward from the Great Lakes. Wednesday into Thursday another cold front will move through the Commonwealth bringing an additional round of rain showers, especially across the western half of Pennsylvania. Then, another strong system will deliver rain perhaps transitioning to some high elevation snowflakes this weekend.

KEY MESSAGE 2: Big temperature swing forecast for the week ahead

Noticeably warmer and more humid conditions expected early this week with max temps on Tuesday forecast to peak 10-15 degrees above the historical average for mid October and possibly challenge daily records with highs in the 70-80F range.

Confidence is increasing in a seasonably chilly cooldown and big temperature swing (vs. early in the week) for the upcoming weekend. The substantial cooldown appears to be delivered in the wake of a strong cold front by gusty west-northwest flow directing the colder air over the Great Lakes. This could setup some lake effect/upslope rain or snow showers (yes, first flakes possible in the Alleghenies/Laurel Highlands) followed by frost and freeze conditions. To quantify the magnitude of the fcst temp swing this week, Bradford could go from 75 degrees Tuesday afternoon to 25 degrees by early Sunday morning (50 degree swing!) If the current forecast verifies, Sunday morning may bring a widespread freeze to the Commonwealth.

AVIATION /08Z MONDAY THROUGH FRIDAY/

The surface low has passed off to the southeast of Pennsylvania, but thick low clouds continue to persist over the airspace. IFR/LIFR conditions over the western and central terminals are likely to continue through the rest of the night, but there is some uncertainty regarding how low ceilings and visibility stay farther to the east. Even though the LAMP shows quite a bit of IFR at all TAF sites tonight, HREF probs of IFR are fairly low after 06Z. Model soundings from the RAP and HRRR paint a similar picture, showing ceilings rising to MVFR at all TAF sites except BFD and JST as winds become more northwesterly.

Ceilings gradually rise through the day today, and while VFR is expected at most airfields for much of the afternoon after 18Z improvements will be slow. The exception will be JST where it might take until early evening for the low clouds to finally dissipate. Winds on Monday will be out of the west- northwest at 5 to 10 knots.

Outlook...

Tue...VFR favored, though a front approaching from the north may bring restrictions in -SHRA. AM fog possible.

Wed...Restrictions from low ceilings and -SHRA possible as the front moves southward across the Commonwealth.

Thu...A period of VFR is favored behind the front, with a chance for restrictions and -RA later on Thursday as the front oscillates back northward.

Fri...Scattered -SHRA and isolated -TSRA could bring restrictions across the region with the front stalling over the region.

CLIMATE

Daily record high temperatures for October 13th: MDT 85/1954 IPT 83/1954 AOO 82/2024 BFD 78/1969 STC 82/1930

CTP WATCHES/WARNINGS/ADVISORIES

None.