The term polar vortex is popping up again, and while it may sometimes sound like a movie trailer for a disaster flick, don't run for your lives just yet. The truth is the polar vortex is always there.
I have a basic grasp on what a polar vortex is but to become better educated on the subject, I decided to talk to fellow meteorologist Rob Paola. The polar vortex is a dome of really cold air that sits over the Arctic in winter. The reason it's there is obvious: it's really cold over that ice pack in winter, and there's also a lack of daylight. It weakens during the Arctic spring and summer as the planet revolves and tilts toward the sun.
Steering winds spin around the boundaries of the vortex. These winds drive the Arctic jet stream, similar to the mid-latitude jet stream that steers storms through our part of the world. Periodically, areas of colder than normal air can separate from the polar vortex and travel south into the mid-latitudes (as is forecast for this weekend). The good news is the weather change is generally short-lived, in the order of a few days or so.
Not to confuse the situation, but the weather that will have you breaking out the heavier coats again this weekend is actually an Arctic vortex (a transitory feature) rather than a polar vortex, which is semi-permanent.
No matter what you call it, it won't feel like spring this weekend.