What do chinooks mean for Calgary?
Anais Loeppky, Staff Writer
This winter in Calgary has been noticeably more delicate than most— and it’s not just a feeling.
According to Environment and Climate Change Canada (ECCC), Calgary experienced record-breaking temperatures this January. These unusually warm conditions are often linked to chinooks, a weather phenomenon common in Southern Alberta.
What is a chinook?
Susan Reid, a professor of earth and environmental sciences at Mount Royal University (MRU), explains that chinooks occur when westerly winds are forced up and over the Rocky Mountains.
“In Southern Alberta, the air has become very dry,” Reid says. “We end up with this warm, dry wind after it flows over the mountains.”
Reid notes that while chinooks are not solely responsible for the warmer-than-average temperatures this January, they have been a noticeable contributing factor.
Impact of chinooks
One of the most evident impacts of chinooks is the welcome break they bring from winter cold. While chinooks are often seen as a positive phenomenon, they can take a toll on both people and local ecosystems.
Reid says one of the main concerns is their impact on vegetation. She explains that when chinooks occur later in the winter, warm spells can cause plants and trees to begin budding early, leaving them vulnerable to damage and frost when temperatures drop again.
Many Calgarians also speak about having headaches and migraines as a result of chinooks.
Migraine Canada found that while 80 per cent of Albertans linked their migraines to chinooks, only 20 per cent truly showed reliable sensitivity to them.
Reid explains that when people experience migraines from chinooks, it is a result of the air pressure change.
Another concern is the rapid melting and refreezing of ice with the temperature change. Reid says it’s important to be mindful of slippery ice following a chinook.
How chinooks form
Reid highlighted that specific conditions have to take place in order for chinooks to form, which require partnership between the wind and the mountains.
“There has to be consistent air flow coming from the west and then forcing that air up over the mountains, because it’s all about the elevation change”.
How chinooks create warmth
Though rooted in thermodynamics, the process by which chinooks create warmth can be explained in relatively simple terms. At its core, the phenomenon is driven by changes in air pressure as air moves over the Rocky Mountains.
“It’s under pressure and can expand as a result,” Reid says. “As air expands, it cools. So it rises and cools up at the top or the peaks, and because it’s cooled off, any water vapour that’s in the air can condense and turn into clouds that later produce precipitation.”
Once the air mass crosses the mountains and begins to descend on the eastern side, it experiences increased pressure and compression. Reid added that when the air finally makes it over the mountains and descends on the east side, it becomes compressed by higher pressure.
As a result, Reid noted that with higher temperatures, moisture is lost, leading to the warm, dry air characteristic of chinook events in Calgary.
Chinooks and climate change
Reid said chinooks are a regular feature of winter in Southern Alberta and can occur multiple times each season when the right atmospheric conditions are in place.
She also emphasised that while warm spells in Calgary are often associated with chinooks, they are not always the cause and can result from other weather patterns.
She also acknowledged that “everyone is very interested in global warming,” adding that “we need to separate the individual weather events from the overall warming.”
