Weather tracker: first red cyclone warning for Réunion since 1989

Cyclone Belal is expected to remain a strong storm through the coming week

Active weather is expected to affect northern Australia and parts of the Mascarene Islands in the south Indian Ocean this week, with the monsoon trough a triggering factor in both cases.

The monsoon trough is an area of the Intertropical Convergence Zone that interacts with the larger scale monsoon circulation. This trough is marked by an area of relative minima in sea level pressure, as well as a local maximum of vorticity (a measure of the spin of the atmosphere).