It’s still not certain there will be a major winter blast, but scientists are watching for colder than normal conditions to develop in the mid-latitudes — where most of the world’s population resides — over the next month or so. Once the polar vortex is disrupted, it can take a month or more to recover, said Andrea Lopez Lang, a meteorologist at the University of Wisconsin-Madison.
“We can see more active and shifted storm tracks and increases in cold air outbreaks in regions across the Northern Hemisphere,” she said in an email.