CHICAGO — Mostly cloudy Friday with waves of thunderstorms. Winds: SSE 5-10 G15. High: 77.

Mostly cloudy tonight with muggy conditions and a chance for thunderstorms. Winds: SSE 0-10 G15. Low: 70.

Saturday Forecast: Mostly cloudy Saturday with a 30% chance of rain/thunderstorms. Cooler lakeside. Winds: SE 5-10 G15. High: 85/81.