How about dynamic fog that appears over time

A lot of people have been talking about re-adding the fog of war to the game. The down side to this is that it could cover some pretty details on the map.
My suggestion is to add fog that appears as the match progresses for some narrative reason.
For instance, on the conq map, it gets darker as ash from the volcano falls over the map. In joust, a cloud falls over the map so it's more of a white fog. On clash it's a sand storm etc.