ITS CALLED A "CHINOOK" IIRC, only reason I know this is because its common up north in the winter in the area of Ft Nelson BC Canada where my wife is from and the first year I went up there and say that i was like WHOOOOAAAA, her dad explained it to me but ive since forgotten much of what he said.. Its pretty normal and Ive since have witnessed it in the greater portland oregon area at night as well as day, at all times... no doom, sorry.. ecks oh...