Santa Ana/Foehn Winds

Santa Ana/Foehn winds (also sometimes known as "Chinook" winds) is the name given to a wind that blows down the eastern slopes of the Rocky Mountains. Initially, wind blowing in from the west hits the mountain range and is forced aloft -- a mechanical process. As the air rises, it reaches its LCL, and the moisture in the air condenses, forming clouds. As the air continues to rise, most of its moisture is lost to precipitation so that by the time it reaches the top of the mountain range, it is extremely dry. The air then moves down the eastern side, adiabatically warming as it descends. The resulting wind is a very warm, dry wind.