textproduct: State College

WHAT HAS CHANGED

* Increased sky cover significantly over the nrn half of the CWA this AM. * Added light rain chances to the SE Wed with TS possible Wed along the MD border.

KEY MESSAGES

1) Big temperature swing ahead with near-record warmth today and frost and freeze expected this weekend

2) Windy and wet end to the week with first flakes

DISCUSSION

KEY MESSAGE 1: Big temperature swing ahead with near-record warmth today and frost and freeze expected this weekend

Max temperatures are still projected to challenge daily records today and Wednesday - esp today. 8H temps get around 18C this afternoon, Most everyone in Central PA will get to 75F with a few going over 80F. However, temps Wed will probably hold about 10F cooler than today in the NW/Allegheny Plateau. The SE could get a couple degs warmer Wed than today. But, isolated/scattered showers Wed could hold temps down a couple of degs from current guidance.

Friday will be the first shot of truly colder air we will experience this fall. A cold front will pass through with temps dropping down near freezing Sat AM in the nrn mtns even though it may be cloudy all (Fri) night there - meaning it could freeze without a frost occurring. Then, Sunday AM looks like everyone could frost up - with many places in the N and Laurels going sub-30F.

-----------------------------------------------------------

KEY MESSAGE 2: Windy and wet end to the week with first flakes

While there will be a few SHRA Wed, mainly S of I-80, the more likely period of widespread wet weather comes Thursday night and Friday. An amplified upper trough will cross the Great Lakes and spin up a deep sfc low in the Gulf of Maine and Canadian Maritimes. While broader in overall coverage, late week rainfall amounts will be on the light side ranging from around 0.50 inch in the NW Alleghenies to 0.10 inch in the Lower Susquehanna Valley.

Gusty winds up to 40 mph are forecast on the backside of the deep low and will deliver much colder air downwind of the Great Lakes this weekend. This pattern will be favorable for lake effect rain and possibly snow showers later Friday into early Saturday over the higher elevations. NBM data even suggests a minor snow accum (<0.5 inch) is possible in the NW mtns and highest ridgetops/summits in the Laurel Highlands. Land/road temps will likely be warm enough to keep any accums to the grass and mulch, not the roads.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Overnight fog and low stratus will have mixed out regionwide by 13-15Z today, when S-SW flow will pick up to around 10-15 kts ahead of a progressive low pressure system sliding across the Great Lakes. A few showers may move across the Northern Tier (KBFD) during the morning and afternoon as the system passes to our north. There is too low confidence on afternoon showers to include in TAFs. Otherwise, little to no precipitation is expected across our area, as supported by upper-level suppression under the right-exit region of a jet streak. This jet streak will likely introduce LLWS concerns across the airspace between 00Z and 12Z Wednesday up to 40 knots and then a continued risk of 30-35 knots after 12Z for the morning. This low level shear will persist through the overnight hours tomorrow until the exit region of the jet has lifted northeast. Mostly VFR conditions expected through the day, but may see some drops down to MVFR or IFR for the northern sites (KBFD and KIPT) as lower ceilings move over the area early Wednesday morning.

Outlook...

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 cold FROPA. W-NW winds may gust up to around 25-35 kts behind the front.

Sat...Localized restrictions possible early due to post-frontal stratocumulus and lake-effect -SHRA/-SHSN, primarily across the Northern Tier. Otherwise, VFR prevailing with NW-NNW wind gusts up to around 25-35 kts possible regionwide.

CLIMATE

Daily record high temperatures for October 13th and 14th:

MDT 85/1954 | 85/1975 IPT 83/1954 | 84/1975 AOO 82/2024 | 80/2021 BFD 78/1969 | 79/1975

CTP WATCHES/WARNINGS/ADVISORIES

None.