Another day followed by another night and early morning of dense fog. A dense fog advisory has been issued which will go into effect later tonight and be in effect until 10am Friday morning. This covers most of the counties east of Interstate 35 and south of a line from Mason City to Guttenberg. Visibilities will be reduced to under a quarter mile or less at times through mid-morning. Be sure to use low beams if you have to ventrure out later tonight or early tomorrow morning.