The winter storms hitting the US this week and forecast to occur during the next couple of weeks, can be tied in large part to the displacement of the polar vortex that occurred beginning in late November, researchers tell CNN.
The polar vortex is a circular current of strong winds over the Arctic that can keep cold air locked up in that region. Recently, though, it weakened and slid southward towards the midlatitudes, bringing cold, Arctic air to heavily populated areas.
This can create stormier conditions, said Andrea Lopez Lang, a meteorologist at the University of Wisconsin at Madison, as that cold air from up north collides with relatively warmer air.
And the weak polar vortex also means a wavier jet stream. These are wind currents that flow west-to-east across the Northern Hemisphere. A wavy jet stream can give people weather whiplash, said Judah Cohen, a meteorologist at MIT. Over the rest of December, we can expect frequent oscillations between milder-than-average conditions and frigid temperatures as storms move through.
However, Lopez Lang cautioned this polar vortex event isn’t the only factor behind those upcoming temperature fluctuations. “It’s definitely contributing, but it’s not the whole story,” she said.
