A forecasting and warning system of storm surge events along the Norwegian coast

We consider the Norwegian Meteorological Institute's system regarding the daily forecasts of water level, and warnings of possible dangerous water level events along the Norwegian coast. The system consists of three parts, the production of water level forecasts, a decision support system, and a system for dissemination of warnings to key users and the general public. Included is a brief description of the forecasting model and the parallel ensemble prediction system, and an assessment of the forecasts produced by them. Based on the assessment of the production models for a three year period we find that they provide sufficiently trustworthy forecasts of water levels for the purpose at hand. Also included is a description of the web based decision support system for issuing warnings. The decision support system was for instance used during the extreme weather event "Elsa" in February 2020, and was found to be an efficient tool both to monitor the event in its early stages and to expedite warnings to key users and the general public.