Same as Fig. 8 for the time interval 21–25 June 2015. This was a storm event with multiple onsets determined in the afternoon, evening and morning sectors (22/06/2015 18:00 UT; 22/06/2015 23:00 UT; 23/06/2015 04:00 UT). The vTEC response was forecasted 6 and 8 h before the first storm onset at DOUR and USAL, respectively. The IRI2012 tends to underestimate the observations with no clear sensitivity to the storm effects.