Cascading Process to Improve Forecasting and Warning Services

The advances in Numerical Weather Prediction (NWP) in the last decades have been tremendous thanks to more, and better assimilated, observations, higher computing power and progress in our understanding of dynamics and physics. These advances, which have led to increasingly skilful weather forecasting, will become even more relevant in the future. Consequently, the emphasis in operational meteorology, hydrology, oceanography and climatology has shifted towards the implementation of increasingly sophisticated and diverse numerical models and applications in order to serve an ever-increasing variety of users.

Operational NWP systems generally provide an accurate indication of developing weather events from hours to days ahead. They are, therefore, one of the most relevant components of routine and severe weather forecasting and warnings at National Meteorological and Hydrological Services (NMHSs). However, the capability among NMHSs in weather forecasting varies enormously. The more advanced NMHSs are making use of the progress in NWP, but those in the developing and least developed countries have seen little advancement due to limited budgets and reduced capabilities. And the gap is increasing.

The Global Data-Processing and Forecasting System (GDPFS) is now being expanded beyond the World Weather Watch (WWW) to encompass all systems operated by WMO Members (including those jointly coordinated with other international organizations such as ICAO). It enables all WMO Members to make use of the advances in NWP by providing a framework for sharing data related to operational meteorology, hydrology, oceanography and climatology.

The main support for the exchange and delivery of these data – that is, GDPFS products – is the WMO Information System (WIS). One of the key benefits of the WIS is the expansion of the range of centres that can connect to the system, increasing the range of GDPFS applications.

Numeric Weather Prediction

Numerical weather prediction uses mathematical models of the atmosphere and oceans to predict the weather based on observational data of current weather conditions.

Data on the weather is collected everyday from weather satellites, Doppler radar, weather stations, weather balloons, and other sources such as aircraft and ships. Computers process the data using mathematical - or numerical – models based on what our scientific understanding about the laws of nature and physics in order to provide weather forecasts. Thus, taking data on current weather, climate and atmospheric conditions, computers use Numerical Weather Prediction models to help forecast the weather for the coming days.

Thanks to developments in numerical weather prediction, a 5-day forecast today is as good as a 2-day forecast twenty years ago. And that development is continuing. “The predictive skill of global numerical weather prediction over the last 30 years has improved by about one day per decade. Our results show that skill continues to improve at a similar rate of about one day per decade even today.” – Alan Thorpe, Head Meteorological Division ECMWF.

However, the challenge remains in mitigating the growing technological gap in weather forecasting. How can we bridge the gap between those who have the knowledge and those who do not, those who have the capacity to run, maintain, develop and support such complex systems and those who do not? Since 2006, the WMO Severe Weather Forecasting Demonstration Project (herein referred to as the Project), a GDPFS initiative, has been working to close this gap by increasing availability and developing capacity to use NWP, including Ensemble Prediction Systems (EPS), in countries where it is not effectively used.

Structure of the GDPFS

The GDPFS is made up of a worldwide network of operational centres operated by WMO Members. Its purpose is to make available to WMO Members agreed products and services for applications related to weather, climate, water and environment, 365 days per year, 24 hours per day. The GDPFS thereby enables scientific and technological advances made in meteorology and related fields to be shared as efficiently and effectively as possible among, and for the benefit of, all WMO Members.

The activities, organizational structure and operations of the GDPFS are designed in accordance with the needs of NMHSs and their ability to contribute to, and benefit from, the system. The GDPFS is a three-level system with various functions carried out at the global (by the World Meteorological Centres, WMCs), regional (by Regional Specialized Meteorological Centres, RSMCs, and Regional Climate Centres, RCCs) and national (by National Meteorological Centres) levels (see figure). It facilitates cooperation and the exchange of information, thereby also contributing to building capacity amongst all countries, including developing and least developed countries.

The accuracy of forecast products provided by advanced GDPFS Centres is monitored by objective verification procedures. The goal is to provide consistent standardized verification of the forecast products of GDPFS Centres so that users can make best use of products and Centres can identify opportunities for improvement. Observational data quality control is an integral component of NWP systems operated by GDPFS Centres, which contributes to an integrated approach to quality management across all the WMO Integrated Global Observing System (WIGOS) components.

The non-real-time functions of the GDPFS include longterm storage of observations, products and verification of results for operational and research use.

The cascading forecasting process

Owing to the high computational cost of global and limited-area NWP, including EPS technique using multiple model runs, few GDPFS Centres have operationally implemented such systems. Many of the latest advances in NWP systems, such as so-called “convection-permitting” models, are particularly suitable for severe weather forecasting in tropical and sub-tropical regions; however, as they are extremely computationally intensive, they are supported only by the leading GDPFS Centres. Moreover, the effective use of NWP and ensemble systems also requires the application of complex model-output post-processing systems to generate forecast products in order to support severe weather forecasting. There are several GDPFS Centres that can provide these sophisticated products (maps of potential vorticity, convection indices, etc.) to forecasters.

Currently designated World Meteorological Centres (WMCs) and Regional Specialized Meteorological Centres (RSMCs),
including Regional Climate Centres (RCCs).

The Severe Weather Forecasting Demonstration Project (the SWFDP is hereafter refered to as “the Project”) was initiated to make the NWP, including EPS, products of the most advanced GDPFS Centres available to all WMO Members. Using a Cascading Forecasting Process, the Project makes global-scale products available to Regional Specialized Meteorological Centres (RSMC) that integrate and synthesize them in order to provide daily guidance for short-range and medium-range forecasts of hazardous weather conditions and weatherrelated hazards to NMHSs in their geographical region. The limited bandwidth of many of the receiving NMHSs is taken to account – they receive products that they can easily download/visualize. Thus, the NMHSs are enabled to issue effective severe weather warnings to disaster management and civil protection authorities in their respective countries. Because NMHSs in a geographical region typically need similar products, the Project makes efficiency gains by coordinating their requirements.

The Project contributes to capacity building by helping developing countries access and make use of existing NWP products for improving hazardous weather warnings. It encourages operational forecasters to use relevant standard or newly developed products and procedures, which have already been introduced in many GDPFS Centres. The initial aim was to show how further cooperative work among operational meteorological centres could enhance the forecasting process of several types of severe weather phenomena, which in turn would improve the warning services provided by the NMHSs. However, the concept has evolved and the expected outcomes now include:

  • Enhanced capability for NMHSs to forecast severe weather and issue warnings at the national level, including improved accuracy and longer lead-times;
  • Established warning processes agreed with national disaster management and civil protection authorities, along with planned responses for protection of lives and property;
  • Established forecast processes and Quality Management Systems (QMS), and strengthened forecast capabilities in support of other user sectors in society (such as agriculture and food security, aviation, marine safety and transportation, etc.) at the national level;
  • Raised awareness of the value of NMHSs with national governments and their agencies, leading in the longterm to greater national support and investment…leading, in turn, to improved supply of observations and feedback into the GDPFS; and
  • Reduced loss of life and damage to property and contributions to the Millennium Development Goals of eradicating extreme poverty and reducing child mortality.

The Cascading Forecasting Process

The Project is implemented in close collaboration with the Public Weather Services (PWS) Programme in order to improve severe weather forecasting and warning services. It also coordinates with other WMO Technical Commissions and Programmes to extend the range of applications and broaden the benefits to other user sectors in society.

The Project conducts near real-time verification and evaluation, based on observations of meteorological parameters collected at local meteorological stations and information gathered on the impacts of the severe weather phenomena. Evaluation of the performance of the cascading process, including the quality of the NWP/ EPS and guidance products, are provided as feedback to the participating centres to further fine-tune the process and products.

Training is a critical component of the Project and is carried out on an annual basis. Forecasters need to know how to make optimal use of the various products coming from the GDPFS Centres. Training is also carried out in service delivery principles and practices including user focus, communication skills and user satisfaction assessment.

Service benefits to NMHSs and society

The value of the Project is not limited to severe weather forecasting; it also supports day-to-day routine weather forecasting. Moreover, it plays an important role in harmonizing the day-to-day forecasts of the NMHSs for a geographical region. Participating NMHSs have increased their lead-time for alerting users – now up to 3 to 5 days – as well as improved their ability to forecast severe weather events. The Project also reinforced forecasters’ confidence in issuing warnings, an important element of communication to users. They now receive recognition from the disaster management and civil protection agencies with which they interact ever more closely. NMHSs are also benefitting from a better public image, and the status and enhanced visibility they have gained has encouraged national investment in Early Warning Systems. It is through the Public Weather Service Programme that the Project assists NMHSs in building effective relationships with users, including emergency preparedness and response stakeholders.

Early in the project’s demonstration phase, a number of hazardous events provided an opportunity to test the application of the Project in an operational disaster situation. During a Project progress meeting held in 2007 in Maputo, Mozambique, the roles of disaster management authorities in the dissemination phase of the Project were emphasized by the landfall of Tropical Cyclone Favio. The Department of Civil Protection – responsible for disaster management activities in Zimbabwe – observed that “there has been a marked improvement in severe weather information and products provided by the Service (the NMHS) since the commencement of the SWFDP in November 2006.”

In 2011, Mr Majodina, on behalf of the Meteorological Association of Southern Africa (MASA), expressed his appreciation for the Project, which represents “a genuine partnership between the developed and the developing world in meteorology.” He further noted the entire region had benefitted because the initial project, which had involved only five NMHSs in 2008, had been expanded to all sixteen countries of the southern African region (at MASA’s request and with additional support from WMO). The annual meeting of the Ministers of the Southern African Development Community also recognized the Project as a contribution to climate change adaptation in improving severe weather prediction and asked NMHSs, in view of the Project’s relevance to regional socio-economic development, to secure the future of the project by allocating sufficient budget for its continuation.

The East African Community (EAC) Heads of National Meteorological Services meeting earlier this year also recognized the significant contributions of the Project to disaster risk reduction, sustainable development and climate change resilience as well as its contributions to vital socio-economic sectors, such as agriculture and fisheries. They agreed that the Project had enhanced the authority and visibility of National Meteorological.

Reuters / UNICEF/ T. Delvigne-Jean / Handout
Women and children wait in the courtyard of the main
hospital in the town of Vilanculo, Mozambique, after cyclone
Favio devastated the town, 26 February, 2007.

Services, and built public and government confidence in the accuracy and reliability of forecasts and warnings of severe weather events. They further acknowledged that the it represents a systematic and practical approach for strengthening the capacity of development and least developed countries, in that it, transfers knowledge and skills to deliver improved forecasts and warnings of severe weather in order to save lives, livelihoods and property.

A core system in all NMHSs

The Project continues to experience important benefits and significant growth. Five regional projects are either underway or under development – Southern Africa, South-west Pacific, Eastern Africa, Southeast Asia and Bay of Bengal/South Asia.

Future plans include the establishment of the Projectservice in further geographical areas. The ultimate goal is to have a core set of high-quality numerical weather prediction and very short-range forecasting systems in use by all NMHSs. This would enhance capability in providing hydro-meteorological forecasting and warning services in support of disaster risk reduction, and take a range of other applications to a new level.

WMO, 2007: Report submitted by the Zimbabwe Departments of Meteorological Services and Civil Protection: Coordination between Zimbabwe Meteorological Services and Disaster Management Authorities, Meeting of the Regional Subproject Management Team, 27 February to 2 March 2007, Maputo, Mozambique.

WMO, 2008: Final Report: Severe Weather Forecasting Demonstration Project–Regional Subproject in RA I–Southeast Africa, Geneva.

WMO, 2008. Public benefits of the SWFDP in south-eastern Africa, MeteoWorld.

WMO, 2009. Severe Weather Forecasting Demonstration Project, MeteoWorld.

WMO, 2011. Report of the meeting of the Regional Technical Implementation Team of the SWFDP for Southern Africa, 32p.

EAC, 2013. Report of the meeting of the East African Community (EAC) Head of Meteorological Services and Ministries in charge for Meteorology.

In-house contributor

Alice Soares, Scientific Officer, Data-Processing and Forecasting Systems, WMO

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