Patchy dense fog has expanded across the state with many airorts seeing less than 5 mile visibility readings. At 8:20 PM, the airports in Carroll and Creston reported one and a half mile visibility, the airports in Mason City and Lamoni reported one-half mile of visibility, and Decorah airport reported visibility of a quarter mile. This has lead to difficult travel around the area. For this reason, the National Weather Service has issued a Dense Fog Advisory for the northern fourth of our coverage area until noon Sunday. If you are out driving tonight or through tomorrow, slow down, use your headlights, and leave plenty of distance ahead of you.