WMO certifies megaflash lightning record in USA

3 months ago 15

Other previously accepted WMO lightning extremes are:

The greatest duration for a single lightning flash of 17.102 ± 0.002 seconds during a thunderstorm over Uruguay and northern Argentina on 18 June 2020.
Direct strike: 21 people killed by a single flash of lightning as they huddled for safety in a hut in Zimbabwe in 1975.
Indirect strike: 469 people killed in Dronka Egypt when lightning struck a set of oil tanks, causing burning oil to flood the town in 1994.

“Investigation of megaflashes is providing new insights into the mesoscale electrical charge variations in Mesoscale Convective System thunderstorms. Furthermore, it illustrates the threat of the newly recognized “bolt from the gray,” analogous to the “bolt from the blue” from isolated cells, but one that can travel many hundreds of kilometers from the main charge generating region,” said lightning specialist and committee member Walt Lyons.

“The only lightning-safe locations are substantial buildings that have wiring and plumbing; not structures such as at a beach or bus stop. The second reliably safe location is inside a fully enclosed metal-topped vehicle; not dune buggies or motorcycles.

If lightning is within 10 km as found with reliable lightning data, go to the 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 Walt Lyons.

Space-based technology

The previous assessments that established the flash duration and extent records used data collected by ground-based Lightning Mapping Array (LMA) networks. Many lightning scientists acknowledged that there are upper limits for the scale of lightning that could be observed by any existing LMA. Identifying megaflashes beyond these extremes would require a lightning mapping technology with a larger observation domain.

Recent advances in space-based lightning mapping offer the ability to measure flash extent and duration continuously over broad geospatial domains. These new instruments include the Geostationary Lightning Mappers (GLMs) on the R-series Geostationary Operational Environmental Satellites (GOES-16, 17, 18, and 19) that recorded the new lighting record, and their orbiting counterparts from Europe (the Meteosat Third Generation (MTG) Lightning Imager) and China (FY-4 Lightning Mapping Imager).

“The extremes of what lightning is capable of is difficult to study because it pushes the boundaries of what we can practically observe. Adding continuous measurements from geostationary orbit was a major advance. 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,” said lead author and evaluation committee member Michael J. Peterson, of the Severe Storms Research Center (SSRC) at the Georgia Institute of Technology, USA.

“Over time as the data record continues to expand, we will be able to observe even the rarest types of extreme lightning on Earth and investigate the broad impacts of lightning on society,” he said.

Details on the working of the WMO Extremes Archive and past evaluations are presented in the book by Randy Cerveny entitled "Judging Extreme Weather: Climate Science in Action" published by Routledge Publishing.

Committee Members (affiliation and countries listed in parenthesis)