* WHAT...Visibility 1/4 mile or less in dense fog.
* WHERE...Portions of central Upper and western Upper Michigan.
* WHEN...Until 9 AM EDT /8 AM CDT/ this morning.
* IMPACTS...Low visibility could make driving conditions hazardous.
* ADDITIONAL DETAILS...Areas in the lower elevations, particularly along the Lake Superior shoreline, may not experience dense fog. Be prepared for changing conditions as you head inland.