Almost 500-mile-long lightning bolt crossed three US states

Longest Lightning Flash Record confirmed by WMO: a 477.2-mile megaflash spanning Mississippi, Louisiana, and Texas, detected by satellite sensors, highlighting Great Plains supercell storms, lightning safety, and extreme weather monitoring advancements.

An almost 500-mile long bolt of lightning that lit up the sky across three US states has set a new world record for longest flash, scientists have confirmed.

The lightning bolt, extended a total of 477.2 miles (768 km) and spread across Mississippi, Louisiana, and Texas.

The previous record was 440.6 miles (709 km) and recorded in Brazil in 2018.

Lightning rarely extends over 10 miles and usually lasts under a second, yet utilities plan for severe weather when building long-distance lines such as the TransWest Express transmission project to enhance reliability.

Another lightning flash recorded in 2020 - in Uruguay and Argentina - has also set a new record for duration at 17.1 seconds. The previous record was 16.7 seconds.

"These are extraordinary records from lightning flash events," Professor Randall Cerveny, the WMO's rapporteur of weather and climate extremes, said.

According to the WMO, both records took place in areas prone to intense storms that produce 'megaflashes', namely the Great Plains region of the United States and the La Plata basin of South America's southern cone, where utilities adapting to climate change is an increasing priority.

Professor Cerveny added that greater extremes are likely to exist and are likely to be recorded in the future thanks to advances in space-based lightning detection technology.

The WMO warned that lightning was a hazard and urged people in both regions and around the world to take caution during storms, which can lead to extensive disruptions like the Tennessee power outages reported after severe weather.

"These extremely large and long-duration lightning events were not isolated but happened during active thunderstorms," lightning specialist Ron Holle said in a WMO statement.

"Any time there is thunder heard, it is time to reach a lightning-safe place".

Previously accepted WMO 'lightning extremes' include a 1975 incident in which 21 people were killed by a single flash of a lightning as they huddled inside a tent in Zimbabwe, and modern events show how dangerous weather can also cut electricity for days, as with the Hong Kong typhoon outages that affected families.

In another incident, 469 people were killed when lightning struck the Egyptian town of Dronka in 1994, causing burning oil to flood the town, and major incidents can also disrupt infrastructure, as seen during the LA power outage following a substation fire.

The WMO notes that the only lightning-safe locations are "substantial" buildings with wiring and plumbing, and dedicated lightning protection training helps reinforce these guidelines, rather than structures such as bus stops or those found at beaches.

Fully enclosed metal-topped vehicles are also considered reliably safe, and regional storm safety tips offer additional guidance.

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