Chinook arch!

Apparently Mom woke up at 3 am and remembered the phrase. Chinook is a term from one of the First Nations of the Canadian Praries where she grew up and is the warm wind that occasionally comes in winter and blows in a sudden weather change. In Calgary it isn't unusual to go to work in -20 C and come home after a Chinook in 15 above weather. The reverse happens as well.