Overview

• The World Meteorological Organization officially certified on July 31 that a 515-mile lightning megaflash from October 22, 2017, is the longest discharge on record.
• The flash spanned from eastern Texas to Kansas City, Missouri, lasting just over seven seconds and producing 64 ground strikes that illuminated an area five times the size of Massachusetts.
• Researchers merged observations from the GOES 16–19 geostationary lightning mappers with Earth Networks Total Lightning Network ground data to verify the record.
• The megaflash originated in a sprawling mesoscale convective system, offering new insights into the physics of large storm charge reservoirs.
• Scientists warn that such extreme megaflashes pose heightened risks to aviation operations and wildfire ignition and emphasize the need for improved lightning monitoring.