In the aftermath of the CME impact, a geomagnetic storm is brewing. Right now it is too soon to determine how weak or strong the storm might be. High -latitude sky watchers should be on the alert of auroras after nightfall (the hours around local midnight are best). Northern Europe, Greenland, Iceland, Canada, Alaska and the northern tier of the U.S. (Maine, Wisconsin and Minnesota) have a favorable chance of seeing a good display.
In Lofoton, Norway, the CME's arrival produced a surge in ground currents outside the laboratory of Rob Stammes.
"The expected CME arrived and showed up on my instruments at 15.10 UTC–a fantastic shockwave followed by a magnetic storm," says Stammes. "This could be a happy day for many aurora watchers."
The first auroras, post-impact, have been sighted in Scandinavia. Ashton Seth Reimer sends this picture from Longyearbyen, Norway:
"All day I was anticipating a beautiful auroral display," says Reimer. "In Longyearbyen, we certainly weren't disappointed. The display lasted for an solid hour before pushing south. I hope the rest of you enjoy the display as much as we did up here."