A Dense Fog Advisory is in effect through tonight for the NE half of Iowa. The expirations are different from each weather office, but to make it simple, the dense fog will slowly end once a cold front pushes through later tonight or very early tomorrow morning. This front could bring some heavy rain along with it. That is why there is a Flash Flood Watch in effect until tomorrow afternoon for the following counties in Iowa, Clinton, Des Moines, Henry, Jackson, Lee, Louisa, Muscatine, Scott and Van Buren. Expected amounts of 1-2 inches of rain (higher in any thunderstorms that develop) on top of 1-2 inches of water on the ground as snow could lead to some flash flooding of urban areas, streams and creeks. Some rivers may also see some quick rises where ice is seen.