Twin Hurricanes the Fujiwara Effect Explained

In might be difficult to envisage the spectacle of two hurricanes dancing together but, in effect, this is exactly what happens when the Fujiwhara effect comes into being.

The Fujiwara effect is named after a Japanese meteorological scientist, Dr Sakuhei Fujiwhara, who first published a paper on this phenomenon in 1921. The doctor had discovered that, in the event that two hurricanes came within a close proximity to each other, namely within around nine hundred miles, they seemed to become inexorably linked around a point that was midway between the pair. Once this occurs, the two hurricanes will begin to circle each other around this central point. However, it should also be mentioned at this stage that the event is not always confined to two hurricanes as occasionally a third storm will join the party.

It is at this point that many have likened the actions of the hurricanes to a pair of dancers. However, in reality it is probably more accurate to make a comparison with two boxers circling each other in the ring, each looking for that killer punch to take out the other. The reason that I say this is because the result of the Fujiwhara event is that the two hurricanes will sometimes merge, although in other instances atmospheric conditions, acting like a referee, will intervene to separate and send the two storms on their separate ways.

In Dr Fujiwhara’s research, it was shown that the ending of the relationship between the two storms depended upon a number of factors. For example, if the two storms are rotating in the same direction, say clockwise, the likelihood is that the weaker of the two will eventually be consumed by its stronger partner. However, if they are rotating in different directions, the result is more likely to be that they will repel each other if they become too close.

Over the past few decades, there have been several examples of the Fujiwhara effect, with both of the results described above being witnessed as the outcome. For example, in 1994, Typhoons Pat and Ruth completed a full circle of each other before becoming one. A year later, there was a three-storm Fujiwhara event. At first, hurricanes Humberto and Iris took a liking to each other and danced for a while. However, this was short lived as Iris became more interested in the tropical storm Karen, which she eventually consumed, leaving Humberto to fend for himself.

Similarly, an example of the separation of two storms can be evidenced from an event that occurred around Florida in late 1994. Here a large storm developed on the coast and moved up the coast. However, an even larger storm developed behind it, caught up and appeared to grab the first storm and fling it away onto a new course.

The Fujiwhara effect is a fascinating hurricane experience to watch from a distance or from a satellite position and is certainly an interesting scientific phenomenon. However, it may not be such a great experience to be caught in the middle of of a hurricane duel.