## _National Meteorological and Hydrological Services (NMHSs)_

At the heart of this enterprise lie the National Meteorological Services (NMSs) and National Hydrological Services (NHSs), which are collectively referred to as National Meteorological and Hydrological Services (NMHSs: Zillman 1999; Rogers and Tsirkunov 2013). As public agencies, they are responsible for monitoring, analyzing and providing information at the national level, particularly for disaster management services, the general public and key economic sectors. They carry out functions in support of the safety, protection and livelihoods of the general population and in line with their international obligations under the conventions of the WMO and related international weather and climate commitments (Zillman 1999).

## _Regional Specialized Meteorological Centers (RSMCs)_

At the regional level, WMO-designated RSMCs are responsible for the distribution of information, advisories and warnings for specific programs (tropical cyclones, environmental emergencies, etc.) as part of the WMO coordinated World Weather Watch. Some also play a crucial role in the cascading forecasting process. The RSMCs take numerical data from the GPCs and interpret the information received in order to prepare daily guidance products for the NMHSs, running limited area models to refine products on a finer time scale, while coordinating certain tasks with participating NMHSs. At the global scale, each RSMC has different, yet specific duties, from monitoring atmospheric radiation to tropical cyclone forecasting, among others (Rogers and Tsirkunov 2013).

## _Global Producing Centers (GPCs)_

Global Producing Centers (GPCs) are at the top of the cascading forecast process. Each center is a WMO certified institution that aims to support RSMCs and NMHSs with the provision of forecasts on the global scale (Rogers and Tsirkunov 2013). They are an essential part of the process because they possess the capacity for computing long-range forecasts covering all of the earth (Rogers and Tsirkunov 2013). The provision of global scale products and services by GPCs enable WMO members to focus on the national and local end user needs to generate early warnings and actionable weather, climate and water information.

## _World Meteorological Organization (WMO)_

With 191 member countries, the WMO provides a framework for international cooperation to ensure the development of hydrometeorological forecasting, including access to data, processing and standardization of related data, technology transfer, training and research. WMO fosters collaboration between NMHSs and contributes to the application of hydrometeorology to public and private services. WMO’s basic mandate has been expanded to strengthen the capacity of NMHSs to generate and provide operationally updated climate forecasting and information products intended for climate services.

# 2.2 Production and delivery of climate and weather services

The provision of hydrometeorological services depends on a complex set of processes starting with essential observations of the atmosphere, land and oceans for such elements as temperature, precipitation, pressure and wind. These observational fields are overlaid with initial estimate NWP products in a critical first step, and then using the skill of forecasters and other techniques and approaches such as trend analysis, experience, local climatology, etc., forecast products (services) 7