Unrelated lightning in Minnetonka, Minnesota, USA. Credit: Chad Davis (CC BY 2.0) via Flickr
A titanic bolt of lightning lit up a whopping 829km of sky from eastern Texas to Kansas City, Missouri in the US. The monstrous streak has set the new record for the longest ever lighting flash.
It went off during a storm in October 2017 but remained undiscovered for almost a decade before observations made by the National Oceanic and Atmospheric Agency’s (NOAA) GOES-16 satellite were re-examined.
The event surpasses by almost 100km the previous record-holder which stretched across 3 US states during a storm in April 2020.
“We call it ‘megaflash lightning’ and we’re just now figuring out the mechanics of how and why it occurs,” says Randall Cerveny, professor of geographical sciences at Arizona State University and rapporteur of weather and climate extremes for the World Meteorological Organization (WMO).
Cerveny is co-author of a report in the Bulletin of the American Meteorological Society which documents the new lightning record.
GOES-16 satellite image recording a record-setting lightning megaflash during a storm in October 2017. Red circles mark positively charged branches of the lightning, and blue circles mark negatively charged branches. Credit: World Meteorological Organization, 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,” he says.
The lightning most people are familiar with extends only 10 to 15km horizontally and/or vertically within storm cells.
Megaflash lightning is on another level.
The supercharged strikes reach lengths of more than 100km, shooting off on average 5 to 7 ground-striking branches from its horizontal path across the sky.
They can only happen within the overhanging anvils and raining stratiform clouds of mesoscale convective systems (MCSs) – some of the largest and most intense thunderstorms on the planet.
Weather satellites capable of continuously detecting and measuring lightning on the continental scale have made documenting these phenomena possible.
The GOES-16 satellite, equipped with a Geostationary Lightning Mapper, detected the world record event in the same year it was first deployed.
“Adding continuous measurements from geostationary orbit was a major advance,” says first author Michael Peterson from the Severe Storms Research Center at the Georgia Institute of Technology, USA.
“We are now at a point where most of the global megaflash hotspots are covered by a geostationary satellite, and data processing techniques have improved to properly represent flashes in the vast quantity of observational data at all scales.”