Application of real time S2S forecasts over Eastern Africa in the co-production of climate services

A significant proportion of the population in Sub-Saharan Africa are vulnerable to extreme climatic conditions, hence there is a high demand for climate information. In response to this need, the Global Challenges Research Fund African Science for Weather Information and Forecasting Techniques has been undertaking a two-year testbed to co-produce tailored forecasts for different sectors using the sub-seasonal to seasonal forecast datasets from the sub-seasonal to seasonal Real Time Pilot Initiative project. Sub-seasonal forecasts are essential for early warning and informed decision-making in the agriculture and food security sector. This study summarises the co-production process of climate services between the Intergovernmental Authority on Development (IGAD) Climate Prediction and Applications Centre and the Food Security and Nutrition Working Group for Eastern and Central Africa, highlighting the importance of efficient communication as well as the lessons learnt and challenges faced in the co-production process. A case study approach is utilised to evaluate the model performance. Two contrasting case studies, one for an extreme rainfall event in week three in April and another for the evolution of tropical cyclone Gati were conducted for the year 2020. Skillful and timely climate information and services co-produced has the potential to increase the uptake, ownership, and appropriate use of sub-seasonal forecasts for resilience building in Eastern Africa.Practical Implication.In the past decades Eastern Africa has been plagued by numerous climate related disasters including flooding and drought. Eastern Africa has a relatively dry tropical climate with a high percentage of the region being arid or semi-arid. To properly plan for these events there is need for provision of weather and climate forecasts. Traditionally forecasts have been mostly issued out at short range and seasonal timescales. Creating a glaring gap in the provision of forecasts between the short-range and seasonal forecasts, thus raising the need for sub-seasonal forecasts. Sub-seasonal forecasts bridge the gap between the short-range and long-range forecasts and are critical for informed decision making in the agricultural and disaster risk reduction sectors over Eastern Africa.Here we propose utilisation of a co-production process to increase sub-seasonal forecast uptake over Eastern Africa. The co-production is implemented through a two-year testbed under the Global Challenges Research Fund African Science for Weather Information and Forecasting Techniques. The IGAD Climate Prediction and Applications Centre collaborated with the Food Security Nutrition Working Group (FSNWG) for Eastern and Central Africa in the co-production process. The FSNWG coordinates regional food security, and nutrition updates to planners and decision-makers (e.g in disaster and risk reduction, agriculture, livestock sectors). In the region the main drivers of food insecurity include climate, conflict and macro-economic drivers. The European Centre for Medium Range Weather Forecasts (ECMWF) model outputs are utilized to derive the forecast information. The co-produced products include weekly total rainfall, rainfall anomalies, probability of exceedance, soil moisture anomalies, maximum and minimum temperature anomalies and also the maximum wet and dry spells. The forecast information is disseminated through bulletins and also during the monthly FSNWG plenary sessions. Sharing of the sub-seasonal forecasts in the monthly meetings allows for further direct interaction between the climate information users and producers. The forecasts are mostly used for crop choice, planting timing, drought risk, flood risk, disease outbreaks, early assistance appeals, disaster relief preparation, and early warning with drought and flood risk tied on top decisions made.One major challenge that is often faced by climate producers and users is the communication of the forecasts. In this study the challenge is addressed by incorporating a communication and user service team based at ICPAC. The communication and user service team is composed of social scientists, climate information experts and journalists. Improved communication is fundamental in increasing the uptake of the sub-seasonal forecasts and appropriate use of these climate products by climate information users. In consequence the communication and user services team at ICPAC simplifies the language that is utilized in the forecast bulletins and also improves on the layout of the bulletins. This improves the readability and usage of the forecast outputs. For example, initially forecast bulletins were written in paragraph format, which potentially makes the readability of the document harder. Hence, it was suggested that the forecast bulletins be produced in bullet point form.To evaluate the model a case study approach is utilized for two extreme events that occurred in 2020. One case focused on an extreme rainfall event in week 3 in April and another for the evolution of tropical cyclone Gati. Tropical cyclones that make landfall over Somalia are rare during the October-December season. Results showed that the model is able to capture the wet anomalies for both case studies, hence giving an indication to stakeholders of potential flood risk. However, the model underestimates the rainfall intensity over the region thus use of anomalies might provide more information on the risk of flooding or extended dry spells in comparison to the total rainfall.In conclusion this study has shown that the S2S forecast information have a potential to provide early warning systems and hence, increase the Eastern Africa community resilience. However, to ensure long term viability of the co-production process there is need for continued support in access to the real time S2S forecast datasets.