JICA backs Viet Nam's quantitative rainfall forecasting technology

Japan International Cooperation Agency (JICA) supports the advancement of quantitative precipitation forecasting to improve localized heavy rain forecast precision across Viet Nam.

At a meeting on September 29 to launch the Project on Advising the development of quantitative precipitation forecasting technology for Viet Nam, Kobayashi Kenichi, Deputy Chief Representative of JICA Viet Nam, said that JICA will implement the project in Hanoi and nationwide from September 2026 to September 2028.

“This is the next step in Japan’s commitment to supporting Viet Nam in strengthening its capacity in hydro-meteorological forecasting in general, and quantitative precipitation forecasting in particular,” Kobayashi Kenichi affirmed.

For extreme, localized, high-intensity and rapidly developing rainfall events, improving forecast accuracy several hours before such events occur is particularly important. Japanese experts will share their experience with the Department of Meteorology and Hydrology and the National Centre for Hydro-Meteorological Forecasting, providing technical support and transferring knowledge for the development of very-short-range forecasting technology.

Specific activities include improving the quality of quantitative precipitation forecasts in both spatial and temporal dimensions; enhancing the use of radar data in forecasting systems; developing ensemble forecasting; improving very-short-range rainfall forecasting systems; enhancing the quality of rainfall estimation and observation data; and studying directions for developing medium- and long-range forecasting systems.

A key focus is to enhance the use of radar data and apply data assimilation methods to improve initial conditions for numerical weather prediction models. Accordingly, observational data from radar networks and automatic rain-gauge stations will be continuously integrated into the models in real time, creating a consistent and accurate input data source for forecasting calculations.

These activities build on the outcomes of Japan - Viet Nam cooperation in meteorology and hydrology through 2025, particularly the 2018-2023 technical assistance project “Strengthening Weather Forecasting Capacity and Flood Early Warning Systems in Viet Nam.”

According to Mai Van Khiem, Deputy Director of the Department of Meteorology and Hydrology, Viet Nam’s hydro-meteorological authorities have initially tested thunderstorm warnings and forecasts from 30 minutes to 2-3 hours in advance. The online thunderstorm warning systems Hymetnet and iWeather are currently operating effectively. Experts from the two countries will continue to improve these systems and enhance forecasting quality, extending the forecast lead time to 3-24 hours. Achieving this will require data assimilation to make full use of observational data from local monitoring networks and improve longer-range forecasts.

In addition to technical assistance, the new project focuses on developing a team of specialists capable of continuing research, development and operation of quantitative precipitation forecasting systems. This includes establishing research and specialized technical teams working on numerical weather prediction models, data assimilation, ensemble forecasting, short-range rainfall forecasting and data quality control. Workshops, training programs, expert exchanges and research activities in Japan will provide Vietnamese specialists with opportunities to gain access to advanced forecasting technologies, methodologies and operational experience.

According to the plan, the project will also promote the sharing of domestic and international research findings, participation in scientific conferences and publication of results in international specialized journals. These activities will contribute to strengthening the research and technology development capacity of Vietnamese specialists.

The project’s implementation is aligned with the strategic orientation of the Department of Meteorology and Hydrology and is expected to improve short-term rainfall forecasting, enhance early warning capacity for heavy rainfall, floods and related disaster risks, and gradually build the technological and human resources needed for Viet Nam to independently improve its quantitative precipitation forecasting system in the coming years.

As the national development plan in Viet Nam, the Prime Minister Decision No.1970 on approving the Strategy for Development of the Hydro-Met sector till 2030, with a vision to 2045, was issued on 23 November 2021. The decision aimed at providing weather information for preventing disasters, not simple weather forecasts, i.e., i) risk information for disasters, ii) prompt information issuance, iii) precise information at the provincial level, iv) cooperation with other DRR bodies and local governments, and v) awareness activities on information usage. 

Khanh Ly