Polar Vortex Has Officially Retreated

Shift In Jet Stream Leads To Winter Storm

Above, an image of the "polar vortex" pushing southward into Wisconsin and Minnesota early last week. Photo: NASA (CC-BY)

The polar vortex that plunged Wisconsin and most of the country into extreme cold last week has retreated, meaning the jet stream has moved north with the cold air.

Tasos Kallas, a meteorologist with the National Weather Service in Green Bay, said last week the jet stream dipped much farther south than it normally does.

“Now, the jet stream has come a little farther north,” he said. “That’s what’s led to this system coming across Wisconsin as opposed to driving down toward St. Louis and Memphis as it has in the past.”

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The system Kallas refers to is a winter storm that has brought snow to many areas of Wisconsin.

Winds gusting up to 40 mph Tuesday night are expected to create low visibility and hazardous driving conditions. Otherwise, Kallas characterizes Tuesday’s storm as “typical” for January in Wisconsin.