It’s called the Fujiwhara effect after a Japanese meteorologist, Dr. Sakuhei Fujiwhara, who first described it in 1921. It’s a fascinating interaction between two nearby tropical cyclones (or other vortices like low-pressure systems). Here’s how it works: The Basics When two tropical cyclones form close enough to each other (usually within about 800–900 miles), their circulations begin to interact. Instead of moving independently, they start to rotate, or orbit, around a common center point betw

Fujiwhara Effect displayed by two vorticies during the formation phase of the Sikeston, Missouri EF3 on May 16, 2025. The Fujiwhara effect, sometimes referred to as the Fujiwhara interaction or binary interaction is a phenomenon that occurs when two nearby cyclonic vortices move around each other and close the distance between the circulations of their corresponding low-pressure areas. The effect is named after Sakuhei Fujiwhara, the Japanese meteorologist who initially described the effect. Bin