'Supercharged': Tornadoes Forming in More Concentrated Bursts During Climatic Change
Several waves of severe weather and tornadoes have impacted the central United States since the start of the year, with some analysts suggesting that the frequency of these events is increasing. Over the past two weeks, a number of outbreaks have resulted in dozens of tornadoes forming in the same regions on the same days.
On Monday and Tuesday of this week, the Storm Prediction Center recorded more than a dozen tornadoes across the Great Plains and Midwest. This is in addition to the outbreaks that occurred on April 26 and 27, when 105 tornadoes were reported, making it the most active day of April.
While the frequency of tornadoes in the US has remained relatively constant over the past several decades, they now occur in more intense bursts over fewer days. Data suggests that this trend has intensified in recent decades. In the 1950s through 1970s, around 69% of tornadoes occurred on days with fewer than 10 occurrences, while only about 11% occurred on days with 20 or more tornadoes. However, since 2000, the trend has shifted, with approximately 49% of tornadoes occurring on less busy days and 29% occurring on days with 20 or more tornadoes.
Scientists attribute the intensity of these outbreaks to the combination of atmospheric instability and wind shear, both of which are influenced by climate change. Though the direct link between the two is difficult to establish, data shows that the conditions for tornadoes are becoming more favorable when they do occur.
Dr. Houser, an associate professor of meteorology at Ohio State University, explained that the two main ingredients for tornadoes are atmospheric instability and wind shear. As warm, moist air near the ground meets colder, drier air above, it creates instability, which is essential for the formation of tornadoes. When this instability occurs, it can cause the air to start rotating, which can then lead to the formation of a tornado.
Additionally, wind shear, or the change in wind speed and direction at different altitudes, is also a crucial factor in the formation of tornadoes. Dr. Houser stated that as climate change alters the atmospheric conditions, there may be fewer days with both instability and wind shear present. However, when conditions are favorable, they are almost "supercharged," leading to more tornadoes on fewer days.
This supports the emergence of more intense outbreaks, as opposed to single tornadoes forming on less eventful days. These conditions have contributed to tornadoes spreading outside of the typical "Tornado Alley" in the Great Plains and are instead being seen in the Midwest, Appalachia, and the Southeast.
While the total number of tornadoes in the US has remained relatively constant, these outbreaks paint a clearer picture of the effects of climate change on their formation. Researchers agree that although there are both geographic and seasonal trends, tornadoes can and do occur anywhere in the US. This article originally appeared in the New York Times.