One Day in the Life of a Chinook

Map Courtesy of the University of Illinois

As a result of a strong Chinook effect at noon MST on December 19, 2003, Cut Bank and Great Falls recorded highs of 59 and 56 degrees respectively. Valier, 20 miles south of Cut Bank, reached 61 degrees. In contrast, Kalispell and Missoula only reached 23 and 31. The temperature map above shows that a large areas east of the Rocky Mountains experienced Chinook winds on that day, as evidenced by the warmer colors extending from Canada to Colorado.

Below: When you compare the topography map below to the temperature map (above) you can see a strong correlation between the Chinook winds and the shape of the land. The warm winds develop on the east slope of the Rockies. In some places this area is called the "Rocky Mountain Front".

Map courtesy of NASA

Not exactly . . .
Many believe that the word "Chinook" means "snow eater" . . . A strong Chinook can make a foot of snow all but vanish in a day as the snow partially melts, and partially evaporates (sublimates) in the dry wind. Others believe the true origin of the name is that "Chinook Wind" in the fur trade era meant that the wind was coming from the direction of the Chinook Indians (the lower Columbia River).


Back to Chinook Effect
This energy demo will help you understand the role of latent heat.
Snow cover image shows the effect of Chinook winds
Current Snow cover image

By Rod Benson
Earth Science Teacher at Helena High School

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