textproduct: State College

WHAT HAS CHANGED

*Lowered dewpoints and minimum RH this afternoon *WPC added a level 1/4 excessive rain risk for Monday 7/27

KEY MESSAGES

1) Pleasant/dry pattern continues into the last weekend of July 2) More humid with potential for strong thunderstorms and heavy rainfall into next week

DISCUSSION

KEY MESSAGE 1: Pleasant/dry pattern continues into the last weekend of July

Valley fog continues to expand over the N&W Alleghenies per latest IR satellite loop. Based on 07Z observations, some of the usually colder sites in this area could print morning low temps in the upper 30s.

Fog will quickly dissipate shortly after sunrise with temps also rebounding nicely under abundant sunshine. The pleasant/dry pattern continues into the last weekend of July. Sounding profiles supported lowering Td this afternoon further reducing RH which is already quite comfortable for this time of year. High pressure migrates over CPA tonight setting up another seasonably cool/comfortable night with more valley fog into early Friday morning.

Wind flow shifting from the north to the south signals a slight warming trend and gradual increase in low level moisture Friday and Saturday. A stray shower or t-storm can't be ruled out Saturday afternoon/evening over western PA with precip odds less than 20%.

KEY MESSAGE 2: More humid with potential for strong thunderstorms and heavy rainfall into next week

The pattern looks increasingly unsettled Sunday into the middle of next week as upper troughing is carved out over the Great Lakes/Ohio Valley into the Mid-Atlantic and Northeast states. Ample northern stream system energies set to dig into the upper trough position will support potential for strong storms and heavy rainfall. WPC introduced a broad level 1/4 marginal excessive rain risk for D5/Monday July 27 that covers most of CPA. Severe storm potential could shift east/southeast on Tuesday. Confidence in where greater risk corridors may develop is low, and will largely be influenced by convective evolution in the Days 4-5/Sunday-Monday periods.

AVIATION /06Z THURSDAY THROUGH MONDAY/

High pressure over the central states will slowly build eastward into Pennsylvania over the next few days. Stratocumulus and cumulus clouds should erode away overnight as drier air continues to move in. Tapering winds and clearing skies will support fog in the deepest valleys across northern PA by Thursday morning. No impacts are expected at area airfields, but the current TAF package includes a mention of vicinity fog at KBFD as that location has the relatively highest chance of impacts.

VFR conditions should prevail into at least the first part of Saturday, before the chances of showers and storms increase later in the weekend. Each day will be marked by dry conditions and generally tranquil weather - ideal for flying.

Outlook...

Fri...Some potential for valley fog across NW PA Friday morning; otherwise, VFR conditions expected.

Sat...Generally VFR conditions with low-end (< 20%) chance of an afternoon shower/storm across western sections of central PA.

Sun...Increasing chances of PM showers/storms, with some restrictions possible.

Mon...Still a chance showers and storms.

CTP WATCHES/WARNINGS/ADVISORIES

None.