At 1200GMT on Saturday 20th August Tropical Storm Mindulle was very close to Iwo Jima and moving north. Tropical Storm Lionrock was 500km south of Osaka and heading west. While Tropical Storm Kompasu was less than 500km east of Tokyo, yet travelling northwestwards.
Tropical storms are steered by winds in the middle atmosphere and are fed by the warmth of the waters beneath them. On first sight, it makes no sense that three storms this close to each other should go in different directions.
Indeed, when any two tropical cyclones are within 2,000km of each other, they may well start “dancing”. They interact in what is known as the Fujiwhara Effect and rotate around a point halfway between each other.
These storms fit the bill but show no signs of interacting now or in the forecast future.