Forecasting the individual components
After a time series has been split into the sum of seasonal, trend, cyclical and residual components, forecasts based on the first three of these can be added to forecast future values in the series.
Tourist arrivals in Fiji
There was a political coupe d'état in Fiji in 2000. As a result, tourist numbers plummeted and the above forecasts substantially overestimated tourist arrivals in 2000.
Forecasts can never hope to take account of such unpredictable events.