DisastersTornadoes occurring earlier in Tornado Alley
About 1,300 tornadoes hit the United States every year, killing an average of sixty people. Peak tornado activity in the central and southern Great Plains of the United States is occurring up to two weeks earlier than it did half a century ago, according to a new study whose findings could help states in “Tornado Alley” better prepare for these violent storms.
Peak tornado activity in the central and southern Great Plains of the United States is occurring up to two weeks earlier than it did half a century ago, according to a new study whose findings could help states in “Tornado Alley” better prepare for these violent storms.
Tornado records from Nebraska, Kansas, Oklahoma, and northern Texas — an area of high tornado activity dubbed “Tornado Alley” — show that peak tornado activity is starting and ending earlier than it did sixty years ago.
An AGU release reports that peak tornado activity, which occurs in the region from early May to early July, has moved an average of seven days earlier in the year over the past six decades. The study’s authors observed the shift in tornado activity for all categories of tornadoes that occurred in the region from 1954 to 2009.
The research team published its findings last week in Geophysical Research Letters, a journal of the American Geophysical Union.
Additional, more-selective analyses by the authors show that for some states in the region and for stronger tornadoes the season advances an average of 14 days compared to 1954.
“If we take Nebraska out [of the data], it is nearly a two-week shift earlier,” noted John Long, a research scientist in the Department of Land Resources and Environmental Sciences at Montana State University in Bozeman, Montana, and lead author of the new paper. For tornadoes rated above F0, the lowest rung on the original Fujita scale of tornado strength, the shift is also close to fourteen days, according to a preliminary analysis by Long and his colleagues that is not included in the new paper.
F1 tornadoes have winds between 117 and 180 kilometers per hour (73 and 112 miles per hour), while the strongest tornadoes, F5, have winds between 420 and 511 kilometers per hour (261 and 318 miles per hour), according to the original Fujita scale. Although the Fujita scale was updated in 2007, Long and his colleagues stayed with the original Fujita scale because most data in this new study originates from prior years.
The new research does not attribute the shift in tornado activity in the region to any single cause. However, the earlier tornado activity seen in the study is in-line with what could be expected in a warmer climate, the study’s authors said.
The new research could help residents in the region be better prepared for severe weather, said Long.
