Lightning in U.S. Underestimated as Dangerous Killer, Expert Says
Bolts of lightning strike far more often than weather records indicate, making electrical storms more dangerous than previously believed, a weather researcher warns.
The reason is that most records on lightning occurrences are compiled by observers who listen for thunder, which is produced by lightning.
But new research shows that between 22% and 40% of lightning flashes occur without thunder being heard.
“It is not good news,” researcher Stanley A. Changnon said of his findings, reported in the August edition of the Journal of Geophysical Research-Atmospheres.
“Those who have to worry about the risk of lightning damage, for example nuclear power plants, have had to use data based on (thunder records) to develop their risk analyses,” Changnon said in a telephone interview.
“It’s very clear that thunder rather dramatically underestimates the frequency of lightning near a given point,” he said.
Changnon, a weather researcher affiliated with the Illinois State Water Survey who also teaches at the University of Rochester in New York, used electromagnetic detectors to record actual cloud-to-ground flashes of lightning.
His report was done in conjunction with his son, David Changnon of Colorado State University, and Richard B. Pyle of the State University of New York at Albany.
Detailed thunderstorm records go back to the late 1800s, Changnon said, but they have always depended on the reports of trained observers, who primarily listen for thunder.
In recent years, however, electromagnetic detectors have been installed in many areas to record actual lightning bolts.
The researchers compared the thunder reports of weather observers with the lightning records from sensors used by the federal Bureau of Land Management in Western states and by electrical utilities along the Eastern seaboard.
“The degree of relationship is relatively weak,” Changnon reported. “It gives one a lot of pause, in many respects, about how the atmosphere works, how good our weather records are and how safe we are.”
In the West, Changnon reported, between 31% and 40% of all lightning strokes were missed by observers listening for thunder.
The situation was better in the East, with 22% to 26% of lightning strokes being missed, the report said.
The differences between observations in the East and the West occurs, at least in part, because of greater problems in hearing thunder in the West, particularly in mountainous areas, he said.
Lightning killed 86 Americans last year, the highest death toll in this decade but lower than the annual average of 96, according to records kept by the National Oceanic and Atmospheric Administration.
The agency counted 365 lightning-related injuries in 1987, about 50% higher than the annual average, due largely to a series of strikes that hit groups of people.
“Lightning apparently does not command the respect it deserves as a dangerous killer,” E.W. Friday, director of the National Weather Service, has warned.
Last year’s death toll was the most since 88 people died in lightning strikes in 1978. But that falls far short of several deadly years in the 1960s, including 1963 when 210 people were killed by lightning.
As usual, Florida led the nation with 11 lightning deaths last year. Tennessee ranked second with six, followed by five in New Mexico and four each in Alabama, Arkansas, Minnesota, Mississippi, New York and North Carolina.
Colorado, Georgia, Illinois, Louisiana, Maryland, New Jersey, Oklahoma and South Carolina each recorded three fatalities. There were two each in Arizona, Kentucky, Missouri, Utah and Virginia. States recording a single lightning death for the year were Kansas, Montana, North Dakota, Pennsylvania and South Dakota. Washington, D.C., also recorded one death.