Polar Vortex: What That Means & Why It Hit Wisconsin

Milwaukee is in the middle of the polar vortex, which is setting its icy grip on the Midwest. The arctic chill is expected to be here through Thursday morning. While wind chills and air temperatures are at dangerous lows, this episode is extreme but not unprecedented.

If you've ventured outside the last few days, you've probably seen many people wearing large jackets, hats and other warm clothing. But Adam Bilsky was walking to work on Tuesday without much winter gear. 

“Idiot is how I’d describe it," he laughed. "Mainly because I’m too vain right now to wear a hat. But it’s a short walk, so I figure, I’ll be alright.”

He has a less light-hearted way to describe the cold, though. "Bracing," he says, though still joking. "I definitely feel the mini icicles forming around the facial hair, especially around the nose.”

You know what it feels like and looks like — this year starting with blizzard-like snow conditions turning into dangerous cold — but where did it come from? The answer: the North Pole.

“[Polar vortex] is traditionally or classically used in meteorology to describe an area of low pressure that sits on top of the north pole in the stratosphere that is about 10 to 20 miles above in the Earth’s surface,” says Judah Cohen, a climatologist at the Massachusetts-based Atmospheric and Environmental Research.

He says circling that area above the North Pole is a fast-flowing ribbon of air, which holds the coldest air in the northern hemisphere.

“And then on the periphery or outside the polar vortex — south of this fast-flowing ribbon of air — are warmer temperatures," Cohen explains. "That’s the typical state of the polar vortex.”

Cohen describes the polar vortex as a fast-spinning top.

“It’s a tight, nice, fast spin, and it’s kinda staying in one location,” he says. 

But starting in early January, says Cohen, additional warm air traveled north from North Africa, made a loop into Siberia, then onto the north pole. “Almost always it comes in through eastern Siberia," he adds, saying he's not quite sure why.

He says the warm air rushed into the Arctic, displacing the air that was there.

“It gets pushed or shoved out of the way. Once it’s been displaced from the Arctic, the next place it can go is the mid-latitudes, and that’s the situation that we have now," he says.

He says this year’s polar vortex then split in two — one stream of arctic air going into Canada and the Midwest, and one heading into Eurasia. While he says this year's record lows are historic, they do rival lows from the mid-1990s or the mid-1980s.

Mike Westendorf, meteorologist for UWM’s Innovative Weather Center, agrees that this cold-air outbreak is maybe not “once in a generation” but it is extreme.

"My concern when we have this kind of extreme cold a) we’re not used to it and b) you’re so used to hearing the warnings that you don’t take it seriously," he says. "For everybody who’s about 21 and younger — I say this because I have kids — they all look at me like ‘Yeah, I’m fine with my earmuffs. I’ll be just fine, dad.’ No you won’t."

Westendorf says, as a result, it’s important to also take it seriously.

“This is killer cold," he says. "This is the kind of cold that you do have to take seriously. If you’re going to be out and about in it, this is a battery-killer kind of a cold. So, you’re going to be looking at all of the different recommendations that people have for us as far as pets to our cars. And if you are going to be traveling, make sure that you communicate with people when you are leaving and when you expect to arrive.”

So, how long is the polar vortex expected to last? Westendorf expects a partial warm-up Friday with temperatures in the teens.