Powerful winds thrown out from thunderstorms are becoming more widespread and more destructive across the central U.S., scientists have found.
The gusts, also known as straight line winds, have seen their geographic range extend by five times over the past 40 years, according to a paper in the journal Nature Climate Change.
These winds are often short-lived, meaning that they are often not picked up by weather stations. Researchers at the U.S. National Science Foundation (NSF) National Center for Atmospheric Research (NCAR) calculated the extending range of these winds using meteorological observations and high-resolution computer modeling.
"Straight line winds are caused by thunderstorms and mostly occur in the central U.S. during the warm season," Andreas Prein, NCAR scientist and co-author of the study, told Newsweek. "The term 'straight line winds' is used to differentiate them from rotating winds caused by tornadoes, however, straight line winds can be as intense as tornadic winds and can cause similar damage."
Straight line winds are spat out of thunderstorms, forming due to rain and hail at high altitudes evaporating and cooling the ambient air, causing rapid movements of air downwards toward the ground. These winds are considered on a par with tornadoes in terms of wind speeds and damage caused to infrastructure and properties, often reaching up to 100 to 150 miles per hour, according to the National Weather Service.
"Straight line wind storms frequently blow over trees and break branches that can damage cars and buildings. However, they can also damage building roofs and damage their outer walls," Prien said. "There are approximately $2 billion dollar losses from straight line winds every year in the U.S. but some events, such as the August 2020 central U.S. derecho, can cause more than $10 billion dollar losses."
Winds are classified as "damaging" once wind speeds exceed about 50 to 60 mph, according to the National Severe Storms Laboratory. Fifty percent of the extreme damage reports from damaging winds are caused by straight line winds, according to property rebuilding company Jenkins Restorations. Buildings can be damaged by these winds directly, with the winds tearing apart roofs and walls, as well as being damaged by fallen trees or flying debris carried by the powerful gusts.
Scientists have now found that these winds are becoming more widespread due to climate change, with the area affected by straight line winds having increased by about 4.8 times across the past 40 years.
"They are becoming more damaging (i.e., faster wind speeds) and affect larger areas. In fact, according to our model, you have a five times higher chance of getting hit by a damaging straight line wind storm during summer in the central U.S. nowadays compared to the 1980s," Prein said. One of the main reasons that causes this change is global warming. Warmer air can hold more moisture, which enhances downdrafts—strong winds that fall out of thunderstorms and hit the surface—due to enhanced evaporation of rain in the air."
Until this study, computer models of how straight line winds are being affected by climate change have not been able to capture the scale of these brief events. Now, however, the researchers have found that climate change is likely making these winds more destructive by increasing the temperature differences between the colder air in the downdrafts and the warmer surrounding air, making it descend even faster and therefore brewing even faster and more powerful winds.
"In general, we expect that climate change will reduce the number of moderate and weak thunderstorms in the future but increase the number of extreme thunderstorms, i.e., those that cause damaging winds or extreme rainfall," Prein said. "This will likely result in increasing damage, particularly in combination with population increases in vulnerable areas."
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Update, 11/6/23, 1 p.m. ET: This article was updated with comments from Andreas Prein.
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Jess Thomson is a Newsweek Science Reporter based in London UK. Her focus is reporting on science, technology and healthcare. ... Read more
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