The first of 2 coronal mass ejections (CMEs) impacted Earth today at 11:59am. In the end it was quite weak and no major geomagnetic storm followed. However most CMEs are polite fellows and knock at the door before they come in. Magnetically we call this a geomagnetic sudden impulse (if no storm follows) or a sudden commencement if one does. It results in a small but definite wobble of Earths magnetic field. It looks like my magnetometer picked up one of these from today's CME. I'm not certain as there's quite a bit of low level "noise" (small peaks on the graph) around the same time. Yet another CME due tomorrow (Monday) at 18:00UT.