What is a RSMC / Tropical Cyclones ?

1/ Introduction

Every year, tropical waters experience about 80 tropical storms or tropical cyclones. These meteorological phenomena are among the most devastating natural phenomena responsible (meteorological or not, like the earthquakes) for about 20 % of the mortality and damages recorded worldwide every year (all natural disasters considered – hence including not only meteorological ones but also other ones like earthquakes).
Their potential for destruction, as a result of related strong winds, heavy rainfall, storm surges, floods and thunderstorms/tornadoes, depends on their intensity and on their structure and is exacerbated by the duration of their impact, and by the extension and vulnerability of affected areas.

Every year, tropical cyclones are responsible for thousands of victims and huge damages. They strongly affect the social and economic life of the impacted areas, and even, in the most extreme cases, they can provoke a severe socio-economic recession for a region or a country, bringing their level of socio-economic development several years back. The names of the very last memorable phenomena; Katrina (2005) and Nargis (2008), are indefectibly associated to the traumatism caused in New-Orleans/Louisiana, and in Myanmar. Even if the Southwest Indian Ocean is not given as much media coverage, it undergoes the cyclonic risk as well. In recent history, the particularly violent and cataclysmic cyclones Eline (2000) and Gafilo (2004) have claimed hundreds of lives in Mozambique and Madagascar.

2/ RSMCs / Tropical Cyclones

The major importance of the tropical cyclone phenomenon (and not only by comparison with the other meteorological hazards, as explained above), justified a specific treatment and organization with the allocation of dedicated means to prevent against this major threat and mitigate as much as possible the disastrous consequences of these meteors for the populations at risk.

Under the responsibility of the WMO, and more particularly of the Tropical Cyclone Programme (TCP) of the World Weather Watch (WWW), a globally and regionally coordinated system for the monitoring and forecasting of all tropical systems worldwide has gradually been set up.

If the National Meteorological and Hydrological Services (NMHS), being in direct relationship with local authorities, and in particular with civil defence authorities or emergency and natural disasters managers, remain an essential link in the chain of alerting the population and managing the cyclone risk, there was a need to set up specialised centres of expertise, in charge of the "first-level" operational monitoring and forecasting of tropical systems.

Using the most modern technological tools, every centre designated and recognised as a Regional Specialised Meteorological Centre (RSMC) is responsible for an area on which it operationally monitors all the tropical systems, from their birth to their death. These centres regularly provide track forecasts, intensity forecasts, and guidance on structure evolution of the storms, primarily to the NMHSs of the concerned region. But the advisories and bulletins disseminated also serve as the official first-level information of reference for the international media and some of the users, such as mariners.

There are six tropical cyclone RSMCs together with six Tropical Cyclone Warning Centres (TCWCs) around the world. These TCWCs complete the tropical systems monitoring and forecasting coverage over smaller areas of responsibility.

The areas of responsibility for the Cyclone Centres (RSMCs and TCWCs).
Source: WMO.

Under the responsibility of the Tropical Cyclone Programme (TCP), technical coordination meetings are regularly organized with members of every RSMCs and TCWCs to ensure the coherence and the global coordination of the system.

3/ Role and missions of a RSMC / Tropical Cyclone

Every RSMC exerts its activities within a regional framework in accordance with an Operational Plan (OP). This OP defines procedures and regional agreements in force to ensure the best operational monitoring of tropical systems in the concerned region. Result of the cooperation between the RSMC and the NMHSs, coordinated by the TCP, this OP is regularly revised and updated.
The RSMC (or TCWC) primary mission is the detection, the monitoring, and the operational forecasting of all tropical systems within its area of responsibility. This mission translates into the provision of regularly updated analysis and forecast advisories and bulletins. Information given by these advisories are the baseline and guidance used by the NMHSs to make their local forecasts and warnings for their national territories and coastal waters.
This operational function normally includes the responsibility of deciding when to assign a name to tropical systems when it becomes necessary (over all the cyclone basins, the naming procedure aims to clearly identify a tropical system as soon it has reached a significant intensity).
Besides, RSMCs have to manage other activities in relation with their operational role: elaborating annual summaries of the cyclone activity, publication of the verification statistics of the forecast accuracy (forecast verification procedures), and maintaining a comprehensive best track archives of tropical cyclones for their area of responsibility.
Beyond its fundamental operational function, the RSMC missions include as well activities such as research and training in the field of tropical cyclones (particularly the training of the forecasters from NMHS), or activities of communication such as popularising and informing the general public in order to increase its knowledge about tropical systems.