UPDATE: Geomagnetic storm strikes! Awesome auroras … See photos

A coronal mass ejection (CME) left the sun early Sunday morning and is joining forces with two earlier CMEs that left the sun a few days ago. All are now heading directly for Earth, with a strong potential to spark auroral displays. It doesn’t mean we’re due for a major space weather event. That depends on how how the magnetic field of the CME connects to Earth’s magnetic field when the CMEs arrive. However, space weather forecasters at NOAA are estimating a 90% chance of polar geomagnetic storms when they do arrive sometime today (June 22, 2015). NOAA forecasters wrote that Sunday’s CME, a much faster CME than the earlier ones, is …

… expected to catch up with the two observed on June 18 and 19, bringing them all to Earth in close succession by the UTC day of June 22, 2015. The CME was associated with an R1-Minor flare event observed at 0142 UTC (9:21 p.m. ET) from Sunspot Region 12371 located near center disk. A G3-Strong Geomagnetic Storm Watch has been issued for June 22, as well as a G2-Moderate Watch for June 23 as the CMEs make their way past Earth.

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Bottom line: A fast-moving CME is joining forces with two earlier CMEs. All three are due to arrive sometime today (June 22, 2015). NOAA forecasters estimate a 90% chance of polar geomagnetic storms when the CME arrives. Aurora alert!