Dec. 27 (UPI) — The polar vortex is linked with a variety of weather phenomena across the Northern Hemisphere, including cold spells in Europe and Asia.
The vortex is also often referenced as the cause of frigid temps in North America. But while the vortex accurately predicts a handful of North American weather patterns, new research suggests tropical air patterns have a greater influence on extreme cold in the United States and Canada.
The stratospheric polar vortex is a river a wind that circles the Arctic, trapping cold air inside. When it weakens and slows down, it becomes slack and cold can spill out, bringing freezing temperatures to Europe and Asia.
When researchers examined the relationship between a weak vortex and cold spells in North America, they found only a loose connection.
“Despite the most extreme cold snaps experienced in North America often being described as ‘polar vortex outbreaks’, our study suggests vortex strength should not be considered as a cause,” researcher Simon Lee, an atmospheric scientist at the University of Reading in England, said in a news release. “We know that a weakened polar vortex allows cold air to flood out from the Arctic over Europe and Asia, but we found this is surprisingly not the case the other side of the Atlantic.”
According to the new research, published Friday in the journal Geophysical Research Letters, atmospheric pattern in the tropics, including those that push high pressure patterns farther north, have a greater influence on the likelihood of extreme cold in North America.
The strongest connection between a weak vortex and cold temperatures occurs in the American West, according to the research. When vortex wind speeds drop, scientists measured a 10 percent to 15 percent increase in the chance of extreme cold patterns developing across western North America.
The new study showed that while the polar vortex doesn’t do a good job of predicting extreme cold in North America, it does accurately predict a few other weather patterns.
“Our results did reveal that the polar vortex strength provides useful information on the likelihood of most weather patterns over the U.S. and Canada further in advance, including some potentially disruptive temperature changes or heavy rain,” Lee said. “The more accurate information populations have about upcoming changes in weather, the better they can prepare.”
The authors of the new study hope their work will inspire scientists to incorporate tropical atmospheric patterns, including El Nino, into winter weather prediction models.