Chinook winds, often just called chinooks, is now normally a reference to foehn winds in the interior West of North America, where the Canadian Prairies and Great Plains meet various mountain ranges, although the original usage is in reference to wet, warm coastal winds in the Pacific Northwest.
Chinook winds are so named because they come from the country of the Chinook Native Americans: the lower Columbia River, west of the Rocky Mountains. The term originated in the local argot of the fur trade, which spread it to the prairies.
A popular (but entirely false) myth is that Chinook means “snow eater”, as a strong Chinook can make snow one foot deep almost vanish in one day. The snow partly melts and partly evaporates in the dry wind. Chinook winds have been observed to raise winter temperature, often from below −20°C (−4°F) to as high as 10°C to 20°C (50°F to 68°F) for a few hours or days, then temperatures plummet to their base levels. The greatest recorded temperature change in 24 hours was caused by Chinook winds on January 15, 1972, in Loma, Montana; the temperature rose from -48°C (-56°F) to 9°C (49°F).
The ch digraph in Chinook is pronounced as in the word “church” in some regions of the Pacific Coast, but as in French (i.e., shinook) in other regions of the Pacific Coast (e.g. Seattle) and on the prairies. This is because the French-speaking voyageurs of the fur companies brought the term from the mountains.
One of the most striking features of the chinook is the chinook arch, which is a band of stationary stratus clouds caused by air rippling over the mountains due to orographic lifting. To those unfamiliar with the chinook, the chinook arch may look like a threatening storm cloud at times. However, they rarely produce rain or snow. They can also create stunning sunrises and sunsets.
The stunning colors seen in the chinook arch are quite common. Typically the colors will change throughout the day, starting with yellow, orange, red and pink shades in the morning as the sun comes up, gray shades in the mid day changing to pink/red colors, and then orange/yellow hues just before the sun sets.