The Chinook Arch
November 14, 2001
The above photo was taken at evening twilight in Calgary, Alberta by Jeff McIntosh. On the lee (eastern) side of the Rocky Mountains in Colorado, Wyoming, Montana, and the province of Alberta in Canada, chinook winds occasionally bring respite from cold weather. Chinook is an Indian name meaning "snow eater." These warm, westerly winds result from downslope winds - air moving across the Rocky Mountains and down onto the prairies. During those cold, dull gray winter days, Albertans sometimes look toward the mountains for the Chinook Arch, a curved patch of blue sky (as shown above) that indicates that warm winds are approaching. Over this past weekend, a strong chinook was felt in Alberta and Montana. Chinooks typically occur from early November to late March.