A warm, dry foehn-type wind that descends the eastern slopes of the Rocky Mountains across the Canadian Prairies and the American Great Plains, capable of raising surface temperatures by twenty degrees Celsius or more within a matter of hours during winter. Known locally as a "snow eater" for its ability to rapidly melt or sublimate snow cover, a strong Chinook has produced some of the most dramatic recorded temperature swings anywhere, including a 1943 event in Spearfish, South Dakota where the temperature rose 27 degrees Celsius in two minutes.
Facts
PeriodicityIn southern Alberta, Chinook conditions occur on average 30 to 35 days per year. 1 ScaleSustained winds typically range from 16 to 60 km/h, with gusts up to 100 km/h. 1 Identification
Distinguishing AppearanceOften preceded by the chinook arch, a band of stationary stratus cloud formed by orographic lifting over the mountains. 1 Connections
Associated With
The Chinook wind of North America's Rocky Mountains is the regional name for the same foehn effect: a warm, dry, adiabatically heated wind descending a mountain's lee slope.
Sources
1. Chinook wind, Wikipedia
Chinooks in Alberta and eastern British Columbia section
Interior Chinooks are most prevalent over southern Alberta in Canada, especially in a belt from Pincher Creek and Crowsnest Pass through Lethbridge, which get 30-35 Chinook days per year, on average.
Lead section
Its speed is generally between 16 km/h (10mph) and 60 km/h (37.5mph), gusting to 100 km/h (62.5 mph).
Chinook arch section
One of its most striking features of the interior Chinook weather system is the Chinook arch, a föhn cloud in the form of a band of stationary stratus clouds, caused by air rippling over the mountains due to orographic lifting.
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