Tropical storms merge in East Pacific

In the East Pacific, two sets of tropical systems are currently undergoing a fascinating and rare process; the Fujiwhara effect.

Multiple tropical systems are currently churning away in the East Pacific, with two interactions of the Fujiwhara effect expected to happen simultaneously to two pairs; Emilia and Fabio, alongside Carlotta and Daniel.

For Carlotta and Daniel, Daniel has since dissipated into a tropical depression, and Carlotta is weakening. Emilia and Fabio continue to mesh as they undergo Fujiwhara.

When two cyclones get close enough to each other, their circulations can interact, allowing them to rotate around one common point, rather than two separate ones. Tropical cyclones can influence each other's circulation up to 1400 km apart.

While it is rare for this weather phenomenon to take place, it's even more significant that it is happening simultaneously to two pairs of cyclones at the same time.

This is also the first time since August 1974 that four named storms have occurred simultaneously in the eastern North Pacific.

In the Fujiwhara effect, if one cyclone is stronger than the other, the smaller cyclone will orbit the larger one, eventually getting absorbed.

In more unusual cases, the effect can be amplified when the cyclones come together. From the two smaller cyclones, one larger and stronger cyclone may form.

In other instances, both can continue dancing around their mutual centre of rotation, before eventually separating on altered trajectories.