It has been a media frenzy. Since January, when a piece of the Polar Vortex made its dramatic trip through the Central and Eastern United States, the misconceptions regarding its origins and actual definition have continued. Whether made in a joking manner or not, some of the ideas regarding the Polar Vortex’s actual characteristics have created a bit of an issue for meteorologists. When using it to describe the pattern, we now have to keep in mind the potential media impacts. To be frank: That is not the way it should be.
The Polar Vortex, in our hemisphere, is a persistent cyclone which is located near the North Pole. It features a counter-clockwise rotating pool of cold, dense air — some of the coldest on the globe, in fact. The vortex moves around to a certain extent, but generally remains in the vicinity of the poles. What separates and moves southward (sometimes towards our area) in anomalous patterns, are pieces of the Polar Vortex which feature characteristics of the vortex itself and similar air masses.
It is no surprise that the Polar Vortex is strongest in winter — but the reasons haven’t been included in the media frenzy. Maybe because the words aren’t as catchy? Who knows. Regardless, the increased temperature gradient between the mid and polar latitudes strengthens the vortex during the winter season. The vortex becomes a harbor for some of the coldest, arctic air which remains typically to our north during the winter months.
During anomalous patterns which feature high latitude blocking ridges, cutoff lows, or even deep troughs in unusual areas, the Polar Vortex can be shifted or a piece of it can break off and move much farther south than the vortex’s center typically will. In the case of our arctic outbreak this past January, a significant piece of the Polar Vortex broke off and moved southward thanks to a tremendous ridge in place over the Pacific/US West Coast. To the east of this ridging, the piece of the vortex which broke off was forced southward.
Maybe most importantly, however, is to reiterate what the polar vortex is not. The vortex is not something that comes and goes — and the news networks which are reporting that it is “Returning” are incorrect. The vortex is always there. What changes, over time, is its position and intensity. The polar vortex also doesn’t bring significant snow in its center — in fact, it is usually so dry and cold underneath it, that only scattered snow showers can develop. The vortex also cannot be visually observed. It is only an airmass — what develops as a result of its presence may be observed (snowstorms, etc) but you will never “see” the Polar Vortex coming.
In our current weather pattern, a piece of the Polar Vortex is forecast to park itself over Southeast Canada. This piece of the Polar Vortex will likely contain additional arctic air, which will keep temperatures much below normal for this time of year. For now, in fact, its presence to our north will suppress the baroclinic zone for storm development so that significant precipitation should stay out of the way until this weekend. It won’t be until this vortex weakens, buckles, or retrogrades that more significant storms/precipitation events may affect the area (maybe later this weekend).