Weather forecasters exhausted the term "polar vortex" when describing the cause of last winter's below-zero temperatures, strong winds and above-average snowfall. But according to Sam Champion, host of the Weather Channel's "AMHQ With Sam Champion," forecasters should be more careful when they use that phrase.
"To call it the polar vortex is incorrect. The polar vortex stays in place. It doesn't slide down," Champion told host Josh Zepps. "If it did, boy, howdy, we'd have a whole lot of problems. We'd have bigger problems than we have in current newscasts to talk about."
Champion explained that "polar vortex" is an official meteorology term that refers to a circle of air -- the coldest on Earth -- around both the North and South poles.
"It sits there, it holds there, because that's just how the heating of the globe has worked, the way the planet's designed. It's where the cold air pools, there's a jet stream -- what we call a polar jet -- that would actually hold that air in place."
When weather patterns create ripples in the jet stream, parts of that polar air shift down into the U.S. Champion likened it to a jump rope:
We have this example of a jump rope: If you held one end and I held another, and you wiggled it or I wiggled it, it would wiggle all the way down the line. The same thing happens with the jet stream. So if you put a force up, like a tsunami moving into the northern Pacific, then you're going to get a dip on the other side of the globe or somewhere along the line there's going to be a little ripple. That ripple allows that cold air, the coldest air that's sitting at the top of the planet, to edge down a little bit, to drift or drip down. Our forecasters call it a lobe of the polar vortex.
Regardless of how forecasters label the phenomenon, Champion predicted that it would cause this year's winter to be just as cold as last year.
"The thing about weather patterns is they stay fairly stable until they change, until something shifts them," he explained. "So we watch these things happen and happen and happen, until something shifts the pattern. We've got our first shot of arctic air now, we see another one next week, according to the models. I have no reason to believe we won't see more early in the season until we shift that pattern."
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