THURSDAY NIGHT: Mostly cloudy, warm and muggy. Scattered showers and isolated thunderstorms. Peak rainfall coverage: about 50% of the metro area. Patchy dense fog possible late, especially areas near Lake Michigan. Winds: Northwest/northeast under 7 mph. Low: 67. Friday opens under a mix of sun and clouds for much of the area, but as a stationary front sags to the south and winds change direction, some patchy dense fog will develop.