Chinook-Canadian Rockies

I was driving West of Calgary midday yesterday, making the journey home to Banff. The Sprinter van I was driving was dancing from side to side, like a candle in the wind. Powerful wind gusts slammed into the van repeatedly, threatening to unseat the tires and vehicle from the weatherworn asphalt. To my left, stretching as far as the eye can see to the south, a grey mass of cloud streaked across the open sky. The line of cloud continued to the north, stretching over the horizon. The cloud resembled a wave pounding onto the beach, with an invisible barrier keeping it from advancing too far over the distant peaks. I was witnessing a Chinook, or Fohn.

Chinook is claimed by popular folk history to mean "Ice-Eater". Actually, it is the name of the people in the region where the usage first derived. The reference to a wind or weather system, 'a Chinook', originally meant a warming wind from the ocean into the interior regions of the Pacific Northwest of the USA. The Chinook people lived near the ocean along the lower Columbia River.

Chinooks are most common over southern Alberta, especially in a belt from Pincher Creek and Crowsnest Pass through Lethbridge. On average, there are 30-35 Chinook days per year. Chinook winds can gust in excess of hurricane force 120 km/h (75 mph). Chinook winds have been known to raise winter temperature, often from -20C (-4F) to as high as 10-20C (50-68F) for a few hours or even days. A strong Chinook can melt one foot of snow (30cm) in one day. Then the temperature plummets back to its base level. Calgary, Alberta gets many chinooks-the Bow Valley in the Canadian Rockies west of the city acts as a natural wind tunnel, funnelling the chinook winds. I was caught in this tunnel, and I and the vehicle were like a steel ball rocketing within a pinball machine.

As I approached the mountains, the Chinook arch, a band of stationary stratus clouds caused by air rippling over the mountains, hovered above me. Though they look like a threatening storm cloud at times, they rarely produce rain or snow. However, many times after travelling under a Chinook arch in the foothills, I have arrived home in Banff greeted by dark skies and flurries.

Entering the mountains and rolling down the road towards Banff, the gusts of wind, while still frequent, were less powerful. Once in Banff, I parked the van in the industrial compound and began to walk home. Now physically exposed to the force of the Chinook winds, I quickly put my ball cap away and pulled my toque over my ears. I have arrived, I am home.

Robert Krysak

Where Chinooks occur most frequently.