A “heat dome” has settled over parts of the western U.S., with excessive heat warnings in effect for millions. While it’s yet to be seen if those temperatures will hit Canada, meteorologists and scientists say the country could still see an impact, likely in the form of storms.
A heat dome is caused by a strong ridge of high pressure that traps warm air underneath it. The ridge acts like a dome, giving it its name, and allows the sun to crank up the heat below and create a heat wave.
“These pressure systems move usually from west to east across the country, (but) occasionally, you can get a situation as a region of high pressure becomes stationary,” University of Toronto Mississauga atmospheric physics professor Kent Moore told Global News.
“For a period of days, or even a week or so, you get these persistent high pressures (and) it gets hotter and hotter and hotter.”
The systems can be deadly, causing hundreds of deaths in B.C. in 2021, and more recently, dozens of heat-related deaths in Mexico last month.
Even if the dome over the U.S. doesn’t move into Canada, the bubble that it creates could still contribute to stormy conditions north of the border.
Jennifer Smith, a national warning preparedness meteorologist with Environment Canada, told Global News that when these domes become “anomalously large,” they can have wide-reaching effects, though it relies on weather systems to already be present.
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“It’s really just that they can’t traverse through the ridge and so they’re forced around it and they follow this boundary,” Smith said. “If storms were to form, they would be ushered around this ridge.”
She stresses that while storms could be active in Canada due to such heat domes, the key is the formation of storms.
“Just because the boundary is there, it doesn’t mean that there is going to be active weather along that boundary, there’s just the potential for it,” she said.
It may be difficult to predict exactly where in Canada such storms could trek as it would depend where the “heat dome” is situated.
If the upper end of it is below the border, John Clague, an earth science professor with Simon Fraser University, told Global News it’s likely the southern Prairies and Ontario could be impacted.
He added that with forecasts expecting more heat domes into this summer, the situation could bring even messier weather.
“(If) this really severe heat persists into July and August, then I think we’re in for a little bit of a rough ride in terms of maybe extreme weather,” Clague said.
Global News chief meteorologist Anthony Farnell said the clusters of thunderstorms that could travel to Canada due to the dome could have torrential rain, frequent lightning, damaging winds and even a tornado risk.
“The frequent rainfall around the heat dome and the bone dry and hot air under the dome only act to strengthen the boundary which creates its own feedback loop,” he said.
He added for storms that enter the Great Lakes region, due to warmer than normal temperatures, the storms would be less likely to weaken as they move into the area.
With Canada expecting to still see above normal temperatures this summer, some heat domes could form in Canada, too.
The 2021 dome in B.C. left more than 600 people dead, and Clague says that’s why people should pay attention to weather forecasts.
“They can see these things coming a few days in advance and so we have to be better prepared,” he said.
— with a file from The Canadian Press
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