Dense fog advisory in effect Posted By: Ben Butler June 17, 2009 @ 5:08 am Today's Local News Tweet Share Email Washington County and much of Southeast Iowa are under a dense fog advisory this morning. The National Weather Service says visibility will be reduced to less than a quarter mile in areas. They advise that motorists slow down, use their headlights and leave plenty of stopping distance in front of them. The fog advisory is expected to expire at 8:00 this morning (6/17)