Chinook

A warm, dry foehn wind that spills down the east side of the Rockies and can vaporize a foot of snow in an afternoon. Native peoples called it the 'snow-eater'; in Montana, Wyoming, and the Colorado Front Range, a Chinook can swing the temperature 40-60 degrees in a couple of hours. Spearfish, South Dakota, famously rose 49 F in two minutes during one event in 1943.