Meteorologists with the National Weather Service are predicting that the northern polar vortex is likely to split once again later this month, into not just two, but three separate vortices that are expected to bring unseasonably cold and stormy weather to parts of Europe and North America.
The polar vortex is a low-pressure area of air that resides over both of Earth’s poles, with the vortex at each pole spinning in a counter-clockwise direction, and bordered around their edges by the jet stream. Occasionally, the Northern Hemisphere’s vortex splits into a number of separate gyres that drift south, bringing colder Arctic air along with them.
Typically forming a stronger current during the winter, climate change has been causing the northern vortex to split more regularly, causing prolonged cold snaps further south, while allowing warmer air from the south to creep into the Arctic between the southbound gyres. Although the occurrence of stronger winter weather can cause its share of problems farther south, warmer air moving into the north can accelerate the already-rapid melting of the Arctic’s ice pack.
The conditions behind the upcoming split were precipitated by a warming event that occurred over Siberia that then flowed north into the Arctic, disrupting the polar vortex’s normal flow. The NWS is forecasting that this time around it will likely split into three separate vortices, bringing cold, stormy weather to Europe and North America late in January.
Typically, the effects of a split in the polar vortex persist for more than a month, although the weather events generated by this split might be exacerbated by the formation of a high-pressure region that is forming over the North Atlantic near Greenland that may stall the west-to-east progression of individual weather systems.