So why is all this important? Why do we care about the Polar Vortex every Winter?

The answer is actually quite simple. This stratospheric polar circulation, called the Polar Vortex, can mean the difference between a very cold and snowy winter and a Warm and dry Winter.

A strong Polar Vortex usually means strong polar circulation. This usually locks the colder air into the Polar regions, creating milder conditions for most of the United States and Europe. In these conditions, the Winter can be mostly warmer than normal across the mid-latitudes.

In contrast, a weak Polar Vortex can create a weak jet stream pattern. The colder arctic air is harder to contain, which can now escape from the polar regions into the United States and/or Europe. Image by NOAA.