We have two atlantic basin tropical storms this week. Predictions are that they will merge at some point near the panhandle of Florida.

To have two tropical systems in the Gulf, potentially making landfall near the same time is unusual and could lead to something that is even more rare – the Fujiwhara effect.

The Fujiwhara effect happens when two tropical systems come near, then orbit each other, or possibly merge into one system.

It is named for Sakuhei Fujiwhara, a Japanese meteorologist who first described the effect in 1921.