Megaflash Lightning Almost 500 Miles Long in the US Sets New Record

The World Meteorological Organization (WMO) recorded two new world records on Tuesday for megaflash lightning in the United States and South America.

The WMO’s Committee on Weather and Climate Extremes used state of the art satellite technology to establish two new records, one of which was for the longest flash of lightning across a horizontal distance that spanned nearly 500 miles:

“The longest single flash that covered a horizontal distance of 768 ± 8 km (477.2 ± 5 miles) across parts of the southern United States on 29 April 2020.  This is equivalent to the distance between New York City and Columbus Ohio in the United States or between London and the German city of Hamburg.

“The greatest duration for a single lightning flash of 17.102 ± 0.002 seconds from the flash that developed continuously through a thunderstorm over Uruguay and northern Argentina on 18 June 2020.”

The new records represent substantial increases from both previous record holders. The new record for the longest megaflash distance is roughly 40 miles longer than the last one. The new record for longest duration megaflash is over half a second longer than the last record, which was set in northern Argentina on March 4, 2019.

“These are extraordinary records from single lightning flash events. Environmental extremes are living measurements of the power of nature, as well as scientific progress in being able to make such assessments. It is likely that even greater extremes still exist, and that we will be able to observe them as lightning detection technology improves,” said Professor Randall Cerveny, a reporter on Weather and Climate Extremes for WMO.

Lightning is a major hazard

Lightning can be incredibly dangerous and even fatal when encountered in the wrong conditions. The most lightning-safe buildings are those that are significantly fortified, while open and semi-covered areas like beaches and bus stops present the most risk. Lightning is known to occur suddenly and travel across large distances swiftly.

“Lightning is a major hazard that claims many lives every year. The findings highlight important public lightning safety concerns for electrified clouds where flashes can travel extremely large distances,” said WMO Secretary-General Professor Petteri Taalas.

The WMO used Geostationary Lightning Mappers and Geostationary Operational Environmental Satellites to record the new records, a significant advancement met from the previous methods of mapping, which used ground-based apparatuses.

“Lightning is a surprisingly elusive and complex natural phenomenon for the impact that it has on our daily lives. We are now at a place where we have excellent measurements of its many facets, which allow us to discover surprising new aspects of its behavior.

“Now that we have a robust record of these monster flashes, we can begin to understand how they occur and appreciate the disproportionate impact that they have,” said lead author and evaluation committee member Michael J. Peterson, of the Space and Remote Sensing Group (ISR-2) of Los Alamos National Laboratory in New Mexico in the US.