We've been having warm weather this week - up to 10 degrees C - due to the warm Chinook winds (something to do with the mountain winds meeting the prairies). It typically forms a pretty defined 'chinook arch' with a solid mass of clouds forming over a clear horizon. It looked pretty stormy today, but doesn't usually result in any precipitation. Lots of people get headaches or other aches during chinooks, but I just enjoy the winter respite!