Chinook Arch. I learned that term when I lived in Calgary. Calgarians say that when they see this, it predicts a change in the weather, from whatever they are experiencing at that moment. The Chinooks were dramatic - You could go into a movie theatre feeling very cold, with your scarf bundled up on your face, and when the movie was over and you went outside it had warmed up so much that you peeled off layers of clothing.
