After Manitoba gets brief reprieve this week, 'you can expect to be cold plenty of the time': weather expert

It's hot, then it's cold, then hot again — or warm for Winnipeg in January, at least.

But the temperature swing southern Manitoba is seeing this week is more typical than residents may think.

"These big temperature swings are actually pretty normal for Winnipeg in winter," said Alex Crawford, an assistant professor of environment and geography at the University of Manitoba.

While it's not quite June in January, Winnipeg is forecast to hit an above-freezing high of 1 C on Wednesday, after reaching a high of just –19 C on Tuesday (–30 with the wind chill, according to Environment Canada).

'"I think the thing that might feel a little bit different right now is that just with a little bit of a nudge of global warming, those really warm days, those warmest days, are warmer than they used to be," Crawford told host Marcy Markusa in a Tuesday interview with CBC's Information Radio.

"When you're crossing that boundary of whether something's at the freezing point or not, we really do notice."

Information Radio - MB5:22Deep Freeze in January: What's Happening with Manitoba's Weather?

This week, temperatures in Manitoba are dropping to a bone-chilling -40°C. Has Mother Nature lost track of the calendar? Has Mother Nature forgotten it’s January? Did Mother Nature miss the memo? To break it down, we’re joined by Alex Crawford, assistant professor in the University of Manitoba's Department of Environment and Geography, who sheds light on this icy phenomenon and the science behind this frosty phenomenon.

Fluctuations occur because of waves in the polar jet stream, the river of fast wind high up in the atmosphere, Crawford said. That air travels around 200 kilometres an hour and separates the frigid Arctic air to the north of the city from the warmer air to the south.

"So whenever that polar jet stream has a big ridge in it, and that ridge comes over Winnipeg, we're going to get warmer than normal in winter," said Crawford.

When there is a trough in the polar jet stream, southern Manitoba is exposed to a pocket of cold northern air and experiences colder temperatures, he said.

"So what's been happening right now, and back in December, is that there's these big ridges and troughs, these big waves in that polar jet stream, and they're leading to these pretty quick switches between colder and warmer."

As for what's coming, weather experts typically look at what is happening in the Pacific and Atlantic oceans to gauge what winter temperatures will generally be like for the Prairie city, Crawford said, but that's a challenge this year.

"If you looked at the Pacific, you'd say we should be a little bit colder than normal this year. But if you look at the Atlantic Ocean, which also impacts Winnipeg, you'd say we should be a bit warmer than normal this year," he said.

"This year is a very hard year to predict for Winnipeg.… The best thing I can say is you can expect to be cold plenty of the time."