Curvy Jet Stream Creates Winter Weather Extremes in North America

Last winter was a rough one for many North Americans, with polar vortexes bringing Arctic temperatures as far south as Florida. Meanwhile, residents on the continent's west enjoyed a relatively mild winter. According to new research this weather pattern, brought on by a "curvy" jet stream, has become more pronounced in the last 4,000 years and may become more so as the climate gets warmer.

Writing in the journal Nature Communications, a team of scientists including University of Utah geochemist Gabe Bowen report that the jet stream pattern that brings winter weather extremes to North America is thousands of years old and that it may be affected by climate change in a way that more frequent and more severe winter weather extremes.

"A sinuous or curvy winter jet stream means unusual warmth in the West, drought conditions in part of the West, and abnormally cold winters in the East and Southeast," Bowen said in a statement. "We saw a good example of extreme wintertime climate that largely fit that pattern this past winter."

"If this trend continues, it could contribute to more extreme winter weather events in North America, as experienced this year with warm conditions in California and Alaska and intrusion of cold Arctic air across the eastern USA," Bowen added.

After analyzing published jet stream data and running computer simulations, Bowen and his colleagues found that the jet stream has become more "curvy" over a 500-year period starting about 4,000 years ago.

"This is one more reason why we may have more winter extremes in North America, as well as something of a model for what those extremes may look like," Bowen said.

More details about Bowen and his colleagues' research is available form the University of Utah.