What is the Polar Vortex?
In recent years, many media outlets have used the word “polar vortex” to explain arctic cold outbreaks, leaving most believing the phenomenon is a new meteorological discovery. However, this term has actually been used in the weather world for decades, first discussed in the 1950s. Although many have hyped up the vortex... insisting it will "hit" the United States at dates in the future, the polar vortex doesn't really "hit" a location, like say, a hurricane's eye wall does. Let’s discuss what exactly the polar vortex is and how it can impact temperatures during the winter season.
First off, the polar vortex describes a large area of upper level (NOT surface) low pressure surrounding the North (and South) Pole, that houses some of the coldest air in the Northern Hemisphere. A strong jet stream circulates the high latitudes (called the polar jet stream), and keeps this arctic air bottled up. Think of the polar jet stream as a “gate” that confines this cold air well to the north. If this “gate” weakens, the cold air can escape into our region. Certain atmospheric events, can lead to this weakening and “break down” of the polar vortex. Sudden stratospheric warming events, strong high pressure ridging, intense Pacific typhoons, and blocking, call all lead to the vortex's expansion and subsequent squeezing into lobes. These can shift further south and cause arctic outbreaks at the surface in Canada, the United States, Europe, and Russia.
In other words, while the polar vortex doesn't exactly "strike" an area, it can lead to colder than normal temperatures in the winter. So the next time you see "polar vortex" in the news, it just means we need to be more mindful of the cold and bundle up a bit more when venturing outside. The nor'easters are the trouble makers...they will bring the heavy snow and wind!