Are Kenya Meteorological Department heavy rainfall advisories useful for forecast-based early action and early preparedness?

Abstract. Preparedness saves lives. Forecasts can help improve preparedness by triggering early actions as part of a pre-defined protocols under the Forecast-based Action/Finance (FbA) approach, however it is essential to understand the skill of a forecast before using it as a trigger. In order to support the development of early action protocols over Kenya we evaluate the 33 heavy rainfall advisories (HRA) issued by the Kenya Meteorological Department (KMD) during 2015–2019. The majority of HRA warn counties which go on to receive heavy rainfall. However in general the total area warned is much larger than the extent of significant rainfall. The three periods of flood impacts during 2018 and 2019 were all preceded by HRA, which warned the counties with recorded losses. By contrast, none of the four flooding periods in 2015–2017 were preceded by HRA. We suggest that access to the UK Met Office Global Hazard Map (GHM) at KMD at the end of 2017 was a key factor in this step-change in skill. Overall we find that KMD HRA effectivly warn of heavy rainfall and flooding and can be a vital source of information for early preparedness. However a lack of spatial detail on flood impacts limits their utility for systematic FbA approaches. We conclude with suggestions for making the HRA more useful for FbA, and outline the developing approach to flood forecasting in Kenya.