Intense Lightning ‘Megaflashes’ Stretched Almost 500 Miles Across Three U.S. States

The bolts, which occurred in 2020, broke records for distance and duration

A satellite image of massive thunderstorm over the southern united states
Scientists used satellites to get a birds-eye view of the jaw-dropping bolts. NOAA

A pair of lightning “megaflashes” that occurred in 2020 set new records for both distance and duration, according to the World Meteorological Organization (WMO).

The first record—for the longest single bolt—was shattered during a storm that hit the southern United States on April 29, 2020. The flash stretched an estimated 477 miles from the central coast of Texas to southern Mississippi. That's about the same distance between New York City and Columbus, Ohio, according to the WMO.

The second record was for a bolt with the longest duration, which was set in South America on June 18, 2020, when a flash illuminated the sky over Uruguay and northern Argentina for a shocking 17.1 seconds. It’s unusual for a lightning bolt to reach more than ten miles or last more than a second, according to BBC

One reason the bolts were so impressive is that they were part of intense storms that produce “megaflashes.” Typical lighting strikes happen when electrical charges jump between clouds, or from a cloud to the ground, but megaflashes can span entire thunderstorm complexes. 

"Most lightning flashes in storms travel only a few miles or so,” says Randall Cerveny, rapporteur of Weather and Climate Extremes for WMO, to CNN's Caitlin Kaiser and Judson Jones. “A megaflash can extend for hundreds of miles!" 

Before the pair of storms in 2020, the previous longest-documented lightning bolt spanned 440.6 miles and was recorded in Brazil in 2018. The former record-holder for the longest duration lightning bolt was set in March 2019 by a 16.73-second bolt recorded over Argentina, Rina Tochinsky reports for NPR

“These are extraordinary records from single lightning flash events,” says Cerveny in a statement. “It is likely that even greater extremes still exist, and that we will be able to observe them as lightning detection technology improves.”

To measure the latest flashes, researchers used space-based observations for a bird's-eye view of the storm. The record-breaking bolts were spotted by the GOES-16 and GOES-17 satellites, which are operated by NASA and the National Oceanic and Atmospheric Administration (NOAA), Live Sciences Stephanie Pappas reports. Previously, scientists had to rely on ground-based observations, which can miss some of the biggest storms.

"We are now at a place where we have excellent measurements of [lightning’s] many facets, which allow us to discover surprising new aspects of its behavior,” says Michael J. Peterson, an atmospheric scientist at Los Alamos National Laboratory who led the work, says in a statement. “There is still a lot that we do not know about these monsters.”