WTF Just Happened?

The science of Regina’s crummiest spring

by Gregory Beatty

Winter!

For six weeks now, Regina media have contrasted the horrendous 2013 spring weather with the balmy paradise we luxuriated in last year.

The stats that have been dredged up certainly are sobering.

In a recent Leader-Post article, Environment Canada climatologist David Phillips said that data going back to 1883 pegs the average temperature in Regina between March 1 and April 22 at minus 0.3 degrees Celcius. In 2012, the average was well above normal at 3.0 degrees.

This year? Minus 8.9 degrees! Here’s another shocker: in a typical spring we have 150 units of what weather specialists call “melting-degree days” that measure sunlight and air temp and their ability to melt snow and ice. In 2012, we had 200 units. This year? Zero!

In the Leader-Post article, Phillips attributed our crap spring and generally brutal winter (which included a record amount of snowfall) to a high-pressure system over Greenland and Iceland that split the jet stream and caused colder-than-normal air to descend on us.

University of Regina Geography instructor Mark Cote disagrees with that assessment, though.

“As much as I hate to disagree with David Phillips, from my looking at the weather over the last six months, it was farther upstream that we saw some blocking patterns. The weather in the mid-latitudes travels west to east, so it was more what was happening in the Pacific rather than what was happening in the Atlantic.”

The blocking that occurred, says Cote, “forced the jet stream into a particular pattern that, for one thing, brought moisture across the Rocky Mountains in one of the preferred paths that gives us precipitation on the Prairies.”

Even though we experienced some pretty extreme conditions this winter, what happened isn’t that unusual, says Cote.

“Climatologically, you expect that trough to sit over central North America,” he says. “That’s the normal situation that we get for a number of different reasons, the presence of the mountains being one of them. The difference this year was that it was able to tap into a source of moisture as well.”

Last October, if you recall, Regina had several minor snowfalls, with winter settling in for good (well, or bad) in early November.

And as we slogged through our own version of Narnia’s fabled “Age of Winter”, how many derisive “global warming, my butt” jokes were cracked, I wonder?

But according to Cote’s colleague David Sauchyn, winter 2012-13, despite its generally snowy and frigid character, was consistent with the theory that rising levels of greenhouse gases in the atmosphere — due primarily to fossil fuel abuse — are heating the planet and causing all sorts of problems from rising sea levels to chaotic weather patterns.

But first: as long-time Saskatchewan residents know, when it comes to our weather, “chaotic” is a relative term.

“The Prairies have by far the most variable climate in Canada,” says Sauchyn. “Really, there’s few places on Earth, outside of maybe central Asia, that have the same variability year to year.”

One factor that works against us is our mid-latitude location. At the equator and the poles, the angle of the Sun tends to stay pretty consistent, so there’s not much fluctuation in the strength of sunlight hitting the Earth.

With us, though, there’s a big difference. In winter, we’re semi-polar. Then in the summer, when the sun is high in the sky, we’re semi-equator. So during a typical year, we experience significant temperature extremes in the range of plus 30 to minus 30 degrees C.

Another factor dooming us to volatile weather, says Sauchyn, is our mid-continental location. “We can’t get much farther from the oceans, and they store a lot of heat and give off a lot of heat. So that tends to moderate the climate,” he says.

To understand how volatile our climate can be, you need only consider the last two winters. Last year was described by climatologists as the second warmest on record. This year, perhaps the coldest.

And the big difference, says Cote, is the amount of snow we had.

“Last year it was drier. You’ll notice this in any winter. As soon as we get permanent snow cover, the mean temperatures drop by about 10 degrees. That’s how important the radiative character of the snow is. So, if you can delay having snow pack, you’re going to have warmer temperatures.”

Once we had record snowfall, a cold spring like the one we’ve experienced was pretty much inevitable.

“It takes an awful lot of energy to melt snow,” says Cote. “That’s why forecasted daytime highs have been higher than what we’ve actually experienced. They’re not taking into account the fact that a lot of the energy is going into melting the snow pack.”

As Cote observed above, one factor that contributed to our record snowfall was the ability of typical weather systems that move through the Prairies to access more moisture than normal.

One principal source of moisture for those systems is the Pacific Ocean, and that ties into global warming, says Sauchyn. Research shows that much of the heat generated in the atmosphere is absorbed by the oceans, which comprise 70 per cent of Earth’s surface.

“It’s having impacts on the ecology of the oceans, and ultimately it’s going to have a dramatic effect on our weather. If the oceans are heating up, more water vapour is being put in the air, and it’s got to come out at some point in terms of more intense precipitation events.”

As you perhaps recall from elementary school geography, Earth has four oceans. As far as our weather goes, the Atlantic and Indian Oceans aren’t really factors, but the Arctic Ocean potentially is — and it’s being impacted by global warming, too, says Sauchyn.

“Global warming has eliminated most of the sea ice from the Arctic. That’s very well documented, and the decline has been fairly rapid. If you eliminate ice cover from the Arctic Ocean, all of a sudden there’s another source of water vapour for Canada. So that means there’s likely to be more precipitation.

“Now, we can’t say that the large amount of snow in Regina in the winter of 2012-13 is the result of [that]. But it fits.”

And that means that as much as we might like to write this winter off as a freak occurrence that will never happen again, we can’t.

“We can’t say it’s not going to happen again, says Sauchyn. “It certainly could.”

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2013-05-02