WMO World Record Lightning Extremes: Longest Reported Flash Distance and Longest Reported Flash Duration

Area of Science:

• Meteorology and Atmospheric Science
• Climate Extremes Research
• Geophysics

Background:

• The American Meteorological Society (AMS) Glossary of Meteorology previously defined lightning discharge as occurring within one second.
• Previous records for lightning flash distance and duration were established, but advancements in detection technology warrant re-evaluation.

Purpose of the Study:

• To validate and report new world records for the longest distance and duration of a single lightning flash.
• To recommend an amendment to the official definition of lightning discharge.
• To underscore the importance of enhanced lightning detection networks.

Main Methods:

• Utilized data from regional lightning detection and measurement networks.
• Reviewed and validated extreme lightning event reports by a World Meteorological Organization committee.
• Assessed the duration and horizontal distance of single lightning discharge events.

Main Results:

• A new world record for the longest horizontal distance of a single lightning flash was established at 321 km (2007, Oklahoma).
• A new world record for the longest duration of a single lightning flash was established at 7.74 seconds (2012, southern France).
• The AMS Glossary of Meteorology definition of lightning discharge was recommended for amendment to replace "within one second" with "continuously."

Conclusions:

• Recent advancements in lightning detection networks have enabled the identification of unprecedented extreme events.
• The validated records reinforce the understanding of lightning's potential dangers.
• The proposed definition change more accurately reflects the nature of continuous lightning discharges.