This last part of January 2019, is predicted to see extremely cold temperatures gripping much of the US and weather forecasters are calling it a polar vortex.
A few years ago, the US experienced a tremendous blast of cold air that gripped most of the nation and they called that a polar vortex, too. The problem is that it wasn’t a polar vortex back then, despite very low temperatures.
A polar vortex is when Arctic cold air temporarily shifts south as if the air in the Arctic Circle has tilted. For a polar vortex to exist, one part of the globe must experience very below average temperatures while the part of the globe that is exactly the opposite must experience substantially above average temperatures. Otherwise, the cold air hasn’t tilted.
The last time they talked about a polar vortex, the US experienced temperatures that were quite a bit below normal. However, while that was happening, northern Europe and Asia were also experiencing temperatures that were well below average. Therefore, it wasn’t a polar vortex. The air didn’t shift or tilt. It was an expansion of cold air, but wasn’t a vortex, though some people tried to claim that it was.
This time around, it is a minor polar vortex, though. The northern half of the country can expect temperatures that are below 0 F. Meanwhile, northern Europe is basking in warm temperatures that are from about 19 F to freezing. This is a little bit above average for northern Europe and Asia this time of year.
In other words, it is an expansion of the cold air, just as happened a few years ago, but it is also a bit of a tilting of the cold air as well. The cold air won’t reach as far south as it did during the last abrupt cold, though, so any tilting of Arctic air is fairly slight. It also isn’t likely to last more than a few days. Still, many places will most likely have the coldest temperatures they’ve experienced in 20 years.