In late 2023, American meteorologist and tornado expert Thomas P. Grazulis created the Outbreak Intensity Score (OIS) as a way to rank tornado outbreaks.
[1] The number of total points determine the rating for the outbreak, which is broken up into seven categories.
[1] There have been three tornado outbreaks which scored more than 250 points on the OIS, reaching the status of "Super Outbreak".
[1] There have been 43 tornado outbreaks which scored at least 120 points, but less than 249 on the OIS, reaching the status of "Historic Outbreak".
[1] There have been several tornado outbreaks which scored at least 30 points, but 79 or less on the OIS, reaching the status of "Major Outbreak".