This step can load or import a time series forecasting model created in Weka's time series analysis and forecasting environment and use it to generate a forecast for future time steps beyond the end of incoming historical data.
This differs from the standard classification or regression scenario covered by the Weka Scoring plugin, where each incoming row receives a prediction (score) from the model, in that incoming rows provide a "window" over the recent history of the time series that the forecasting model then uses to initiate a closed-loop forecasting process to generate predictions for future time steps.
For more information, including procedures on how to use this step, see Using the Weka Forecasting Plugin on our WEKA wiki page.