An integrated model, from catchment to open sea, is provided. It includes a catchment model, a coastal circulation model based on SHYFEM and an open sea model. The prototype of the operative chain is tested using available operative datasets from CMEMS. The prototype developed predicts water level, 3D temperature, salinity and circulation in the Western Black Sea. The hydrodynamics provided by the forecasting system accounts for the variability due to the meteorological (wind and mean sea level pressure), freshwater inflows, seasonal, inter-annual and inter-decadal scale processes. The forecasting system prototype well captures the seasonal variability of the sea temperature in the investigated area. reproduce the long-term sea level variability as well as the major fluctuations associated with intense meteorological events (storm surges in the range of 1-10 days). The prototype has a high potential if uptaken from regional monitoring authorities, toward the inclusion of a full operational system.