Extreme weather becoming more common, climatologists say

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This article was published 09/07/2021 (1536 days ago), so information in it may no longer be current.

SCORCHING heat, clear dry skies and a prevalence of fires have made for an extreme week of weather in southern Manitoba. Climate experts say to expect more of the same in the months and years to come.

“What we’re seeing this year is, unfortunately, a taste of what we’ll see more often in the future,” said Danny Blair, a geography professor at the University of Winnipeg and co-director of the Prairie Climate Centre.

Blair said it’s difficult for climatologists to assess how unusual the weather has been in 2021 — particularly as record-smashing heat waves struck the West Coast just weeks ago — but while some have called it a one-in-1,000-year event, climate experts have long-warned the rising temperatures and extreme weather are here to stay.

In Manitoba, recent conditions prompted several mercury-shattering hot days, with temperatures reaching as high as 38 C in Lynn Lake and dozens of daytime heat records broken across the province.

Meanwhile, there are currently 30 active wildfires, a provincial spokesperson said in an email Thursday, with smoke blowing across southern Manitoba from blazes on both sides of the Ontario border and from fires east of Lake Winnipeg.

Many such fires were sparked by lightning from recent storms, the province said. While Manitoba has seen fewer fires this year than average (146 to date compared to an average 243) the severity of this year’s dry weather is still cause for concern.

The current heat wave is the result of a high-pressure system dubbed as a “heat dome,” said Blair, and as global climates change these systems are more likely to stay in one place for longer periods of time. Typically called an “omega block,” the heat dome is a loop-shaped pressure system that bars other weather systems — such as warm, wet rains — from making their way in.

“The longer they stick, the worse the weather is going to be underneath,” said Blair. “The sun pours in and heats up the ground, especially if the ground was dry to begin with, and that means all the heat that’s absorbed at the surface is converted into heat that we feel in the air.”

Manitoba, as with many parts of Western Canada, has experienced dry conditions for the better part of nearly a year-and-a-half, said Blair, producing a “good old-fashioned drought” that exacerbates summer heat waves.

Natalie Hasell, a meteorologist with Environment Canada, said Manitoba has seen little rain since last summer, and with minimal precipitation comes a greater risk for fires and hot weather. The Prairies are in need of “a big system” to “dump widespread rain,” but have so far seen just thunderstorms — which produce only short and localized precipitation — with no clear sign of change on the horizon.

“For most of the Prairies, we are seeing most of the models pointing to above-normal temperatures,” said Hasell. “There is a good reason to believe drought conditions will continue, but there’s no guarantee either way.”

Hasell warned smoke and heat could be trapped in the region for extended periods of time, if winds don’t pick up speed or change direction.

As the global climate warms, Blair explained, jet stream shapes and speeds change, meaning slower winds and longer-lasting extreme weather systems for many years to come.

“As the globe warms up because of carbon emissions… the difference in temperature between the north and the south is less than it used to be,” he said.

Without significant temperature variance, winds slow down and the dominant east to west jet stream forms unmoving “loops” like the heat dome, Blair said.

This year, the West has been stuck under a hot, dry loop, but in years to come Blair said, Western Canada can expect to be stuck under extreme wet spells — and extreme cold events such as a winter “polar vortex.”

“Everybody should be expecting to see more extremes,” said Blair. “That’s climate change; with this more energized atmospheric system, more heat, you must expect more extremes in heat and precipitation variability.”

julia-simone.rutgers@freepress.mb.ca

Twitter: @jsrutgers