textproduct: State College

WHAT HAS CHANGED

* Severe threat for today is winding down, but a gusty thunderstorm can not be ruled out in NW PA tonight.

KEY MESSAGES

1) Upper low over the Great Lakes will move southeast tonight then pull off to the northeast Monday. Showers and thunderstorms will move through the northern tier periodically through early Tuesday.

DISCUSSION

KEY MESSAGE 1: Upper low over the Great Lakes will move southeast tonight then pull off to the northeast Monday. Showers and thunderstorms will move through the northern tier periodically through early Tuesday.

A 70 kt jet max at 500 mb rounding the base of the upper trough over the Great Lakes will provide deep synoptic lift for an area of rain with embedded thunderstorms pivoting across NW PA tonight. Storms have been severe warned in Ohio as they have come off Lake Erie, but they are expected to weaken significantly as they move southeastward towards central PA. There is some degree of west-east training with these storms, so northwestern Warren Co may end up seeing as much as 0.75-1.00 of rain, mostly falling before 2 AM. Less rainfall is expected to the south and east, with little to none south of I-80 and east of the Laurels.

We expect less coverage of SHRA/TSRA Monday without good PVA moving across. However, the cold pool aloft and heating should make isolated to scattered convection along at least the northern tier. It is unlikely that any precip will get south of I-80, but there will be plenty of clouds. Some showers will linger into the night and possibly early Tuesday before drier air works in as the upper trough departs.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Upper level trough swinging across the area along with a west to southwest flow over the Great Lakes will continue to bring clouds and periods of rain mainly across the Laurels and northwestern PA. Weather pattern more typical of late September than late August.

A band of steady rain will be on a weakening trend as it moves inland from the Lake Erie shoreline, but may still bring low MVFR to IFR conds at BFD between 0230z and 06z. JST, UNV, and IPT are also likely to pick up at least some showers with this band, but lesser impacts. Behind the area of rain, lower cigs are likely to set in with mostly MVFR conditions, although drops to IFR are possible at BFD and JST just before daybreak (50 pct chc).

For Monday, isolated showers and possibly a thundershower remain in the forecast across the northern tier. Cumulus and stratocu will build through the day, but bases will generally rise to VFR levels in the afternoon. MVFR cigs are expected to linger longest at BFD.

Outlook...

Tue...MVFR cigs possible in the AM across the NW, then trending VFR.

Wed...Patchy morning fog, otherwise mainly VFR conditions.

Thu-Fri...Chance of showers and storms again, mainly Thursday PM.

CTP WATCHES/WARNINGS/ADVISORIES

None.