A polar geomagnetic storm (Kp=5) is in progress following the impact of a CME around 1100 UT on Sept. 9th. This could be the first of several hits from a series of CMEs expected to reach Earth during the weekend. High-latitude sky watchers should be alert for auroras after nightfall.

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© Rob StammesInstrument room polar light center, Lofoten Norway
Electrical ground currents caused by the storm have been detected in Norway. Rob Stammes writes:
Today, September 09, 2011 at 12.45 UTC the first CME arrived as a magnetic shockwave on my instruments. There is also an effect in signal strength from my vlf receivers, coming through electrons in the solarwind cloud. The magnetic field is unstable at the moment, it means a big change for auroras coming night.