Scientists recently discovered the Polar Vortex is once again unstable, meaning this upcoming winter will be an extremely difficult one to bear.
The polar vortex, the roaring river of air winding around the North Pole, holds the cards. What they reveal could be very disturbing and a harbinger of extreme winter weather in the Eastern United States.
Judah Cohen, a climate researcher at Atmospheric and Environmental Research, monitors the condition of the vortex, every day checking the latest prediction models for any sign of disturbance. He is concerned about what some models are projecting at the end of December or early January.
When the vortex, perched some 60,000 feet (18 kilometres) high in the atmosphere, is stable, winter conditions over the United States and Europe tend to be rather ordinary. Winter is still winter, with the normal mix of storms, cold snaps and thaws.
But when the vortex is disrupted, an ordinary winter can suddenly turn severe and memorable for an extended duration. “[It] can affect the entire winter,” Cohen said in an interview.
Rewind to February of last year to understand the implications. Up to that point, the vortex had held in its stable state, and the winter was a mild, unremarkable one. But then, abruptly, the vortex split.
Predicting the next polar vortex disruption
Cohen shares insights on the state of the polar vortex on his blog and Twitter feed. Last week, he tweeted: “Confidence is growing in a significant #PolarVortex disruption in the coming weeks. This could be the single most important determinant of the weather this #winter across the Northern Hemisphere.”
Vortex disruption is associated with a phenomenon known as a sudden stratospheric warming (SSW) event. The stratosphere is the layer of air in which the vortex resides, above the troposphere, where most weather occurs (there is also a tropospheric polar vortex, which is at times linked to the vortex in the stratosphere).
During such a stratospheric warming event, the prevailing winds decrease or even change direction, the layer warms, and the vortex is displaced and sometimes splits apart.
Cohen’s methodology may provide clues about vortex behavior not just months but years into the future, since it is linked to Arctic Sea ice extent, which is in decline.
As climate warming continues to shrink sea ice in the Barents-Kara sea region in coming years, “that will tend to increase polar vortex disruption,” he said. In other words, the continental United States, Europe and Asia may face a future of wild winters.