A Wave Forecast for the Helsinki Archipelago in the Gulf of Finland

Operational wave forecasts provide valuable information about the sea state for the heavy marine traffic in the Baltic Sea. They also serve as a first readily available information of the wave conditions in case of an accident. In this paper we present a validation of a new coastal forecast for the Helsinki archipelago in the Gulf of Finland. The significant wave height and peak wave period were compared with measurements from a wave buoy inside the archipelago near Suomenlinna. A comparison with seven months of wave buoy measurements from 2017 showed that the performance of the forecast is adequate but depended on the wave direction. The forecast was most reliable for south and south-westerly waves, while easterly waves tended to be overestimated. The forecast quality showed practically no deterioration over the 54-hour forecast length.