Wednesday, August 26, 2015

Chinooks -- winds of the Canadian Rockies

Image from the Huffington Post

Between November and April or May, warm westerly winds called Chinooks blow across the eastern slopes of the Rocky Mountains, bringing a welcome break from winter from the foothills across southern Alberta.

These winds have strange effects.They can infuse the air with a positive charge so strong it electrifies wire fences. Though they push heavy chinook arches of cloud, they rarely bring precipitation.

Chinooks can change the temperature fast. In 1983, for instance, in just four hours, Calgary temperatures rose from -17 to +13, an increase of 30 degrees C. Nearby Pincher Creek once felt a precipitous rise of 41 degrees in a single day. In Claresholm, Alberta, a Chinook brought sudden record balmy 24 degree weather in February.

Chinook winds are fast and strong, and may break trees. In 1962, Lethbridge experienced  a strong Chinook that gusted to 171 km/h. Driving during these winds can be extremely dangerous, as driven snow blows swirls across roadways. Occasionally, large trucks have been blown off the highway and trains derailed by Chinooks.

Because of sudden changes in air pressure, some people suffer from headaches or migraines during Chinooks. Others suffer from earaches, irritability or sleeplessness when these winds blow.

The word Chinook is said to  mean snow eater in the language of a native nation of the same name.

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