April to June each year usually sees the transition from the southern to the northern hemisphere tropical cyclone season.
During this time it is possible to see cyclones in both hemispheres simultaneously. Furthermore, cyclone ‘twins’ sometimes develop at approximately the same longitude either side of the equator.
For the first time since 2009 cyclone twins have developed in the Indian Ocean.
This was caused by a strong burst of westerly winds along the equator about a week ago. A large mass of clouds located in the same area initially moved eastwards with the wind.
The clouds furthest from the equator then started to curl northwards in the northern hemisphere and southwards in the southern hemisphere due to the earth’s rotation. Over time these cloud masses have consolidated and started to rotate to produce twin tropical storms.
The southern hemisphere storm has been named Jamala and is currently not expected to affect any land areas.
The northern hemisphere storm has been named Mahasen and there is a stronger likelihood of this making landfall next week on one of the Bay of Bengal’s coastal regions.
Regional warnings for Tropical Storm Jamala are produced by the Tropical Cyclone warning Centre at La Réunion in the South Indian Ocean.
Regional warnings for Tropical Storm Mahasen are produced by the Tropical Cyclone Warning Centre at New Delhi, India.
The Met Office routinely supplies predictions of cyclone tracks from its global forecast model to regional meteorological centres worldwide, which are used along with guidance from other models in the production of forecasts and guidance.
You can see the latest image of Tropical Storms Jamala and Mahasen at: