Design and evaluation of a community and impact‐based site‐specific early warning system ( SS‐EWS ): The SS‐EWS framework

The recent extreme rainfall events in Spain such as the storm Gloria have highlighted the gaps in emergency communication, particularly the disconnect between the available impact‐based early warning systems (IBEWSs) and the steps communities take during emergencies. This paper presents a community‐centred framework named ‘site‐specific early warning system’ (SS‐EWS) to co‐design and co‐evaluate with communities an IBEWS for vulnerable locations within high‐risk areas. The components of the framework guide communities in identifying and evaluating local impacts; establishing impact and advisory tables; deriving impact‐based rainfall thresholds and warning levels; and configuring the SS‐EWS with radar‐based nowcasting and numerical weather prediction (NWP) models. A first implementation and evaluation of the SS‐EWS have been done for a public school, two ford crossings and the city of Terrassa, Spain. The SS‐EWS shows promising results in triggering location‐based or site‐specific warnings compatible with the reported impacts and proposing actions to reduce the local risk. Furthermore, the combination of NWP and radar‐based nowcasting improved the capacity of the SS‐EWS to monitor the evolution of the precipitation and capture highly intense rainfall. The SS‐EWS can be a straightforward and cost‐efficient complement for regional EWS to increase the preparedness of communities.