textproduct: State College

WHAT HAS CHANGED

No significant changes with this update.

KEY MESSAGES

1) Scattered strong to severe thunderstorms possible Thursday PM, along with a potential period of very heavy rain in the Lower Susq Valley

2) Variable sky conditions for the lunar eclipse Thursday night

DISCUSSION

KEY MESSAGE 1: Scattered strong to severe thunderstorms possible Thursday PM, along with a potential period of very heavy rain in the Lower Susq Valley

Scattered thunderstorm development is expected Thursday afternoon ahead of a cold front across CPA. SPC expanded the level 2/5 severe t-storm risk southward to include the Lower Susquehanna Valley. WPC upgraded the ERO to level 2/4 for areas near and to the east of US-15. Short term model guidance continues to highlight the eastern 1/3 of CPA with the most favorable CAPE/shear profiles and highest pwats/slowest storm motions. A predominantly multicellular storm mode is expected with damaging winds the primary threat, however a few supercells may also be possible. Southwest flow along a southwest-northeast oriented slow moving cold front could yield multiple rounds of training convection in the southeast, with rainfall totals potentially topping 2 inches in spots. Higher FFGs could offset the flash flood risk in the eastern zones to some extent, with the most saturated soils and lowest FFG over the southwest quadrant of the CWA. Subsequent shifts will continue to evaluate the need for a flood watch in the southeast.

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KEY MESSAGE 2: Variable sky conditions for the lunar eclipse Thursday night

Forecast viewing conditions for the lunar eclipse range from fair to poor Thursday night across central PA. The eclipse will begin at 10:34 pm EDT and last for about 3 hours, ending at 1:52 am EDT Friday. The worst view is most likely over the eastern half of CPA due to exiting storms and associated cloud cover. The eclipse will take place during August's full moon, commonly referred to as the Sturgeon Moon. It will also be the last full moon of the summer with the next full moon set to rise a few nights after the autumnal (Fall) equinox on September 22nd.

A drying trend is forecast Friday through the last weekend of August, thanks to high pressure building into the area behind the cold front. This will likely setup a couple of foggy mornings. Rainfall looks fairly limited heading into the first week of September; however despite the start of meteorological Fall the summer is not over with temps expected to rise above the historical average into the 80-90 degree range.

AVIATION /06Z THURSDAY THROUGH MONDAY/

VFR conditions are favored through the rest of the night, though some patchy fog could form around BFD and IPT. There is also some potential (< 30% chance) for MVFR ceilings to develop at MDT and LNS after 06Z as a warm front lifts northward into the morning. This should also trigger scattered showers that will continue through 12Z. Showers and thunderstorms that have developed ahead of a cold front over Ohio and Indiana are expected to weaken as they move eastward overnight and coverage of any showers is expected to be too low by the time they make it to Central PA to include any mentions in the TAFs for western sites.

Most guidance shows numerous thunderstorms developing over the region during the early afternoon as this cold front continues to track eastward. PROB30s have been included for all airfields, though the timing will have to be adjusted as confidence increases. Thunderstorms will be capable of producing strong wind gusts, potentially in excess of 40 knots, and very heavy rainfall that may lead to brief periods of IFR visibility. The highest possibilities for these strong winds are at IPT, MDT, and LNS.

Outlook...

Fri...Fog and a few lingering showers in the morning, becoming VFR for the afternoon.

Sat-Mon...AM Fog; otherwise VFR.

CTP WATCHES/WARNINGS/ADVISORIES

None.