I've read that most people dream mostly in black and white, but remember in color. *shrug* I have no clue where or when I read that, I just remember it from somewhere. However, what you're describing seems to be more than just black and white...like with the cloudy/stormy sky thing. Like the black and white is an actual aspect of the dream itself, rather than just the medium it's being portrayed in...like a painting of paint...if that makes any sense!