A Dense fog advisory is in effect for most of the state of Iowa today through Noon on Tuesday. The visibilities will drop to less than 1/4 mile by this evening.
The fog will be slow to lift because of a weak area of high pressure that is sitting right on top of eastern Iowa. That is causing the moisture to be trapped at the surface.
Now we have to worry about freezing rain and ice with another low pressure system that is going to move out of the Rocky Mountains tomorrow and give us freezing rain tomorrow night through Thursday.
There is a very good chance for slick roads and ice accumulations. Higher wind by Thursday could also cause power lines to snap under the pressure of the ice and wind oscillating the power lines.
Plan for extra problems on the roads Wednesday afternoon through Thursday.