Comment Section

varSITI campaign event
The largest geomagnetic storm at Earth for this solar cycle, this event registered a Dst peak below -200. Based on both the in-situ signature of the event and the ENLIL solar wind prediction for this date, I think it is likely a CIR played a role in making it so strong. Also based on the C2 and C3 images for the day, it appears there is a slow CME launching around noon on the 14th with a small but visible filament. On the morning of the 15th a partial halo CME, associated with a long duration flare that fell just short of M class and from the same active region, launched propagating to the East of the Sun Earth line. I think it is likely that an interaction between the CME+shock of this event and the previous blob CME, as well as the added energy from the CIR and fast speed stream behind the CME likely caused the severity of the geomagnetic activity at the Earth (Hess)

Image Data