Rising temperatures at the North Pole are causing parts of the polar vortex to split and move south, leading to the possibility of a particularly harsh winter in the US, Europe and Asia.
The polar vortex, which the National Oceanic and Atmospheric Administration (NOAA) defines as “a large area of low pressure and cold air around the North and South poles of the Earth”, generally remains strong and stable, as it did last winter.
As reported by The Washington Post, when it remains stable, cold air remains in the area over the Arctic, with much less chance of snow in the regions of the Middle Atlantic and Northeast.
However, recent stratospheric temperature spikes are raising concerns about the impacts they will cause on climate events in the U.S.
Amy Butler, a research scientist at the NOAA Chemical Science Laboratory, told the Post that stratospheric warming events that unbalance the polar vortex are triggered by an upward flow of “large-scale atmospheric waves” from the lower atmosphere.
The stratosphere can then transfer energy in waves that move downwards, leading to blizzard conditions in some areas.
This happened, for example, in the winter of 2013 to 2014, when broken pieces of the polar vortex caused blizzards and heavy snow in cities like Chicago, Washington, DC and Boston.
Judah Cohen of Atmospheric and Environmental Research in Massachusetts told the Post that while he and other meteorologists are trying to analyze the possible impacts of the recent breakdown of the polar vortex, “no one will care until there is snow in people’s yards.”
Cohen added that it is not yet clear whether the warming will affect parts of the United States, as similar warming last year did not unbalance the vortex enough to lead to a particularly harsh winter.
The Post reported that stratospheric warming events occur about six times a decade on average.
Cohen and other experts predict that this year, stratospheric warming is likely to lead to a split polar vortex scenario, with one center over Eurasia and the other elsewhere.
According to the Post, Cohen added that while there may be major snowstorms in the U.S., the divisions of the polar vortexes tend to be concentrated near Europe.