Topband: really weird propagation

[N7DF]

This morning I saw T31EU posted many times on DXSCAPE on 160 so I turned on the rig to listen for him...at 1305 he was 20 over S9 but within a minute he had faded out completely..strangely enough I could not hear any of the stations calling him...within another couple of minutes his signals were back up and I noticed that he several times called stations who never came back to him..This pattern seemed to persist for the remainder of the morning until he faded out completely around 14:40.. Spaceweather.com reports a pending geomagnetic storm but nothing unusual at the time I was listening..there has been a prolonged period of over 20 days of zero sunspots so that probably has something to do with it..I do not think I will ever understand 160 meter propagation but that is one of the things that makes it so interesting