textproduct: State College

WHAT HAS CHANGED

Lowered daytime temps and stratified rain for Thursday Added +RA and gusty winds to SPC/WPC MRGL risk overlap Increased fog coverage Thursday night into Friday morning

KEY MESSAGES

1) Locally heavy rain and a few strong thunderstorms possible across south central Pennsylvania Thursday

DISCUSSION

KEY MESSAGE 1: Locally heavy rain and a few strong thunderstorms possible across south central Pennsylvania Thursday

A broken and thin line of convective rain showers (not much ltg) continue to track south southeastward this afternoon along a weak llvl convergence boundary drifting southward from US-6 toward I-80. Most places in CPA stay dry through tonight with increasing cloud cover. This puts fog formation in a pickle, but any period of prolonged clearing could result in late night valley fog particularly over north central PA.

CAMs are in decent agreement in bringing a slug of moderate to locally heavy rain across CPA from southwest to northeast Thursday morning into Thursday afternoon -- most likely impacting locations near and south of I-80. Heavy convective signals for both +RA and potential strong to severe t-storms ramp up just south/east of the CWA closer to the I-95 corridor tomorrow afternoon into the early evening.

Rain exits CPA by Thursday evening with clouds gradually clearing out by late Thursday night. This should allow for widespread valley fog to develop into early Friday morning. The cold front can't penetrate much farther south of the MD line, so can't rule out a spotty shower/t-storm in far southern PA Friday afternoon. However, most of CPA will see a dry end to the week.

An upper trough carving out over the Great Lakes will bring increasingly unsettled weather conditions over the weekend. There is still considerable uncertainty with timing, intensity, and coverage of storms, but it shouldn't be a washout by any stretch. This system will also deliver some relatively cooler air both at the surface and aloft. This setup could prove favorable for clusters of gusty t-storms with small hail. The troughing pattern holds on into next week which favors temps near to slightly below the historical average for late August.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Some fog is beginning to develop across northern PA and IFR ceilings have developed at IPT. Expect continued expansion of the fog through the rest of the night, with BFD and UNV having the next highest chance of seeing IFR cigs/vsby at some point tonight. Confidence in fog formation is lower at the other TAF sites.

A swath of steady rainfall will overspread central PA this morning, with KUNV/KIPT looking to be within the core of this swath (meaning higher confidence in MVFR-IFR visibility restrictions), with KBFD/KJST/KAOO more-so on the periphery (more intermittent MVFR-IFR restrictions, especially where rain is more showery). Rain at KMDT/KLNS looks to be more showery/convective in nature, with a few strong to severe thunderstorms possible in the afternoon. Rumbles of thunder may occur in the steadier, more stratiform swath of rain where MUCAPE may rise to 100-250 J/kg (primarily KUNV/KJST/KAOO).

Winds will tend to be variable near the system's track over southern PA, with winds generally N/NE north of the system & S/SE to its south. Cloud ceilings lower to MVFR-IFR later during the afternoon and evening in the vicinity of the low pressure center, with low stratus and/or fog possible overnight as low-level moisture persists while mid/high clouds clear out and winds lighten.

Outlook...

Fri...AM fog, otherwise trending VFR.

Sat-Sun...Scattered to numerous showers/t-storms likely. Breezy.

Mon...VFR returns for early next week.

CTP WATCHES/WARNINGS/ADVISORIES

None.