It might sound contradictory, but a blast of warm air high up into the Earth's atmosphere could soon plunge parts of North America and Europe into a deep freeze.
Meteorologists are predicting a sudden stratospheric warming event is on the horizon, although what impact it will have is unknown. In 2018, such a disruption to the polar vortex, a circle of strong winds surrounding an area of low pressure above the North Pole, sent cold air from Siberia westward, plunged Europe into record-low temperatures in late February, and resulted in the "Beast from the East" that dumped up to 22 inches of snow in the United Kingdom. In March, frigid temperatures arrived in the U.S. northeast and East Coast, and many parts didn't see the cold recede until late April.
According to the National Oceanic and Atmospheric Administration, a SSW event happens when a large and rapid temperature increase in the Earth's mid- to upper stratosphere, about 18 to 31 miles above the surface, throws the polar vortex off kilter. It thus sends cold air into the troposphere, where all weather occurs, and could lead to extreme cold-air outbreaks in parts of North America, northern Eurasia, and Siberia.
"A major disruption of the polar vortex is increasingly likely based on weather model forecasts referred to as sudden stratospheric warmings," Judah Cohen, a seasonal weather forecaster with Atmospheric and Environmental Research, wrote in a blog post Monday. "Often following SSWs, more severe wintry weather becomes more widespread across the Northern Hemisphere."
Simon Lee, an atmospheric scientist at Columbia University, tweeted Wednesday if this SSW occurs, it would be the third since the one in February 2018 that led to the "Beast from the East."
"This simple fact is the easiest way to emphasize that a B from the E is not the average response to an SSW," Lee wrote in the tweet.
In another tweet Monday, Lee wrote "it is increasingly likely that a major sudden stratospheric warming" will take place between Feb. 14-17, but added the Global Forecast System model "seems to be on the extreme end of ensemble solutions."
It could be at least another week before predictions can be made about the severity of this SSW, should it even happen.
"Usually we can make the first more reliable predictions only starting around the time when the sudden stratospheric warming happens," Daniela Domeisen, a professor at the Institute for Atmospheric and Climate Science in Zurich, told The Washington Post. "For North America, these predictions are even more difficult than for Europe."