Forecast statistics for “gradual” geomagnetic storms. (a) Storm predictions using real-time data input. (1) final Dst_p; (2) the earliest prediction of Dst_p within 25% of actual storm magnitude; (3) the predictions of Dst_p, which were out of 25% range; (4) maximal predictions of Dst_p obtained during the storm development; (5) maximal predictions out of 25% range. (b) Storm predictions using final data input. (6) final Dst_p; (7) the earliest prediction of Dst_p within 25%; (8) the predictions of Dst_p, which were out of 25% range; (9) maximal predictions of Dst_p obtained during the storm development; (10) maximal predictions out of 25% range. (c) The advance warning time (in hours) of the Dst_p forecast using real-time input.