Answered by Andrew McKaughan – Meteorologist – National Weather Service – Pocatello
Over the last few years, the polar vortex has received widespread attention from the press and on social media leading many to believe that it is a new weather phenomenon. In reality, this phenomenon has been present for thousands of years but has only recently gained notoriety. So what exactly is it? The polar vortex is a persistent, large-scale, upper-level low pressure system that rotates counterclockwise near the North Pole. For most of the year, this feature rotates around the polar regions of the northern hemisphere keeping cold air focused across the Arctic. Occasionally however, this low-pressure system, full of arctic air, can weaken and travel from its usual position. As this system weakens, part of the polar vortex can break off and migrate south, bringing plenty of cold air with it. When this occurs, areas as far south as Florida may experience arctic weather as a result.
These dips in the polar vortex can bring very cold air to any part of the country, including Idaho. Depending on the time of year and magnitude of the cold air intrusions, impacts across Idaho can range from temperatures just a few degrees below normal to record cold temperatures including those well below zero. It’s important to note however, that not all cold weather is because of this feature. More often than not, the vortex remains focused across the polar regions. Can the polar vortex be predicted? Yes, thanks to information obtained by NOAA weather satellites, weather balloons and surface observations computer models are able to help us forecast when a piece of the polar vortex will dip down into the United States bringing frigid temperatures which could have significant impacts on agriculture, travel and everyday life.
Try this at home!
If you spin a top (Like the one from the movie Inception) you will notice that when it is spinning fast it hardly wobbles. This is normally how the Polar Vortex works. When the top starts to slow down or bumps into something it starts to wobble. This is what happens when there are changes in the Polar Vortex system. The super-cold snaps we experience are when the wobbles dip and bring us the arctic cold.