A massive heatwave has been scorching parts of the Pacific Northwest and Canada this week, and all of it is due to a heat dome.

What is a heat dome?

So what is a heat dome, exactly? Well, the dome “is essentially a mountain of warm air built into a very wavy jet stream, with extreme undulations,” according to CBS News.

That jet steam can become wavy and long, which will freeze pressure systems in place for a long time. The pressure system will then be “stalled or stuck in places they typically would not be,” according to CBS News.

This massive heat wave is scorching the Pacific Northwest and Canada
Heat 'dome' makes much of US feel like steam bath

So, as CBS News reports, the high-pressure system has become stuck in the Pacific Northwest, leaving a dome of heat above the area. Weather can’t move through the area now as hot air continues to fill up inside the dome. The air then sinks down and, well, heat scorches the world beneath the dome.

A heat dome can happen when “a strong change (or gradient) in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter,” according to the National Ocean Service

There is no timetable for how long a heat dome can last, according to USA Today. Triple digit temperatures are expected throughout the rest of the week

It doesn’t appear Utah’s recent heat wave has been associated with the heat dome.

Why the dome is significant

Nick Bond, a Washington state climatologist, told The Guardian that the dome is hurting the region because it cuts off cooler air.

  • “That is important here in the Pacific northwest with the present event because it has served to essentially shut off the flow of cool marine air off of the Pacific into the land area,” Bond said.

And, he said, this is a rare occurrence for the Pacific Northwest. It probably won’t occur for another few decades.

  • “It blows my mind that we could get the temperatures that we’re observing here in the Pacific northwest, especially on the west sides of the Cascades that (have) that proximity to the ocean, that it could get that hot for so many days in a row,” Bond told The Guardian. “I would have been willing to guess something like that in the middle of the century, in the latter part of the century.”