There was a very weak CME impact yesterday, that caused very weak Aurora near dawn, but not the large impact expected from the emission on Thursday. The disturbance was not enough to trigger and Aurorawatch alert. Conditions may remain disturbed for this evening leading to a slightly elevated chance, but unlikely to be the big storm we were expecting. So it looks like no treat for us this Halloween after all...

The solar wind (particles that constantly stream outward from the sun) has a typical speed of 400 km/s. A coronal mass ejection (CME—the emission from the sun that causes Aurora) typically has a speed of 1000-2000 km/s.

The ACE satellite sits 1.4M km sunward from Earth, measuring the solar wind speed. You can see the data here: ACE SWEPAM DATA. The yellow trace shows the current solar wind speed and when this rapidly increases well above 400 km/s then the CME is 15 minutes away!