Extreme Weather in the United States Linked to Wave-Like Wind Pattern Variations

What's responsible for extreme weather? It may be all about wind patterns. Scientists have found that variations in high-altitude wind patterns expose particular parts of Europe, Asia and the U.S. to different extreme weather conditions. The findings could help researchers predict and prepare for some of the more extreme weather that hits our cities and countries.

High altitude winds normally flow from west to east around the planet. However, these winds don't follow a straight line. Instead, the flow meanders and forms a wave-like pattern from north to south. It's these wave patterns in particular that can either suck warm air from the tropics or cold air from the Arctic. Then, the wind patterns steer this air, or rain-laden storms, to other locations.

In order to learn a bit more about these wind patterns, the researchers took a look at month-long heat waves, cold spells, droughts and prolonged wet periods. In the end, they found that the development of the wave patterns actually leaves certain Northern Hemisphere regions more susceptible to extreme weather.

"The impacts of large and slow moving atmospheric waves are different in different places," said James Screen, one of the researchers, in a news release. "In some places simplified waves increase the chance of unusually hot conditions, and in others the risk of cold, wet or dry conditions."

For example, the researchers found that western North America and central Asia are more prone to heaves waves, while eastern North America is more prone to extreme cold spells. In addition, larger waves can lead to droughts in central North America.

"The study revealed that these types of events are stronger related to well-developed wave patterns, and that these patterns increase the chance of heat waves in western North America and central Asia, cold outbreaks in eastern North America, droughts in central North America, Europe and central Asia, and wet spells in western Asia," said Ian Simmonds, one of the researchers, in a news release. "The findings are very important for decision makers in assessing the risk of, and planning for the impacts of extreme weather events in the future."

The findings are published in the journal Nature Climate Change.