Talk about a bolt from the blue.
Scientists July 31 announced the discovery of the world’s longest lightning flash ever detected – a whopping 515-mile-long bolt that blasted across central U.S. skies from Dallas to Kansas City in October 2017. In East Coast terms, that’s equivalent to the distance from New York City to Charlotte, N.C.
This single, continuous lightning discharge, of a type now called a “megaflash,” is roughly 40 miles longer than the old record.
The bolt was entirely in the sky, and never hit the ground. “This new record clearly demonstrates the incredible power of the natural environment,” said Arizona State University geographer Randall Cerveny.
Overlooked until now
The flash event was found in a reexamination and reanalysis of past satellite lightning data, which had been overlooked until now. The findings were published in a paper in the Bulletin of the American Meteorological Society.
“It is likely that even greater extremes still exist, and that we will be able to observe them as additional high-quality lightning measurements accumulate over time,” said Cerveny, who serves as rapporteur of weather and climate extremes for the World Meteorological Organization, the weather agency of the United Nations.
The record “megaflash” was detected with help from lightning detection equipment onboard satellites in orbit around the Earth.
What is a ‘megaflash?’
Most lightning flashes are limited to less than 10 miles in reach. When a lightning bolt reaches beyond 60 miles (100 kilometers to be exact), it’s considered a megaflash, according to a statement from Arizona State University. Less than 1% of thunderstorms produce megaflash lightning, according to satellite observations analyzed by Michael Peterson of the Georgia Tech Research Institute.
Megaflashes arise from storms that are long-lived, typically brewing for 14 hours or more, and massive in size, covering an area comparable in square miles to the state of New Jersey. The average megaflash shoots off five to seven ground-striking branches from its horizontal path across the sky.
While megaflashes that extend hundreds of miles are rare, it’s not at all unusual for lightning to strike 10 or 15 miles from its storm-cloud origin, Cerveny said. And that adds to the danger. Cerveny said people don’t realize how far lightning can reach from its parent thunderstorm.
Lightning kills dozens, injures hundreds more
“Lightning is a source of wonder but also a major hazard that claims many lives around the world every year,” said World Meteorological Organization Secretary-General Celeste Saulo, in a statement.
Just in the United States, an average of 20 people are killed and hundreds injured each year by lightning, according to the National Weather Service. Most lightning strike injuries occur before and after the thunderstorm has peaked, not at the height of the storm.
“That’s why you should wait at least a half an hour after a thunderstorm passes before you go out and resume normal activities,” Cerveny said. “The storm that produces a lightning strike doesn’t have to be over the top of you.”
‘Bolt from the gray’?
This new record flash illustrates the threat of the newly recognized “bolt from the gray,” analogous to the “bolt from the blue” from isolated storm cells, “but one that can travel many hundreds of kilometers from the main charge generating region,” lightning specialist Walt Lyons said in a statement.
“The only lightning-safe locations are substantial buildings that have wiring and plumbing; not structures such as at a beach or bus stop,” he said. “The second reliably safe location is inside a fully enclosed metal-topped vehicle; not dune buggies or motorcycles.”
Lyons said that if lightning is within six miles – as detected with reliable lightning data – go to a lightning safe building or vehicle. “As these extreme cases show, lightning can arrive within seconds over a long distance, but they are embedded within larger thunderstorms, so be aware,” said Lyons.
This article originally appeared on USA TODAY: World record lightning flash detected: 515 miles long
