Wind power forecasting is used for different purposes, as summarized in Table A1. The planning horizon ranges from several days ahead to real-time operations. In our review, we found areas of application from transmission outage planning, transmission security and peak load analysis, to reliability unit commitment, hour-ahead market bidding, and real-time commitment and dispatch. The wind power forecasts are used as input to some of the procedures for system and market operations outlined in Section 3. However, the ISOs/RTOs have limited experience in this area so far and are continuously working on improving and automating the use of wind power forecasting in DA and RT operations.