textproduct: State College

WHAT HAS CHANGED

Added key message and discussion for increasing risk of extreme heat to end June and start July

KEY MESSAGES

1) Much needed/second chance rainfall opportunity for the Lower Susquehanna Valley early today

2) Increasing heat risk to end June and start July

DISCUSSION

KEY MESSAGE 1: Much needed/second chance rainfall opportunity for the Lower Susquehanna Valley early today

Slower-to-exit cold front (thanks to trailing/developing sfc low pressure wave from eastern VA to southern portions of the DelMarVa) will provide another opportunity/second chance for much needed rainfall across the southeastern portion of the forecast area early today with the main focus over the Lower Susquehanna Valley (LSV) particularly southeast of I-81. PWs will still be quite high this morning, so we can't rule out a couple of localized heavy thunderstorms/downpours. Showers should exit the southeastern zones by this evening with clearing skies and pleasant conditions (lower humidity) for Wednesday.

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KEY MESSAGE 2: Increasing heat risk to end June and start July

A major pattern change over the Pacific Northwest and Intermountain West this weekend will likely result in a downstream upper ridge developing over the eastern U.S. by early next week. Blended ensemble guidance driving the prototype probabilistic heatrisk is confirming the signal for a building to potentially prolonged heatwave to end June and start July. CPC has placed a 20-40% slight risk of extreme heat over CPA from 6/30-7/6 with higher chances in the 40-60% range in southeast PA. High humidity and temperatures (highs in the 90s with heat index values possibly reaching 100F) will greatly increase the risk of heat-related illness.

AVIATION /08Z TUESDAY THROUGH SATURDAY/

With the exception of LNS, the wind at all other airfields has switched around to NW or North, with dewpoints falling a few degrees over the past several hours. However, plenty of low clouds around as low levels are still moist (mostly MVFR and IFR, but LIFR at JST). While the heaviest rain from the first batch of precip ended last evening, a second batch of light to moderate rain showers will develop along the slow moving front this morning and likely clip MDT and LNS, finally wrapping up by 16-18Z. Conditions should improve with clearing skies from NW to SE through this afternoon. Northerly winds will gust 15-20 kts before tapering off this evening. Areas of fog and low stratus will likely form across western PA between 06z-12z Wed, with probability of IFR conditions ranging from 30 pct at BFD to 10-20 pct chc at the other airfields.

Outlook...

Wed...Mainly VFR, dry conditions expected.

Thu...Restrictions possible in another round of showers and storms late.

Fri-Sat...Restrictions possible in additional showers and storms.

CTP WATCHES/WARNINGS/ADVISORIES

None.