G2 geomagnetic storm in progress

Earth is under the influence of a positive polarity coronal hole high speed stream today, December 21, 2016, which is causing geomagnetic storms reaching G2 Moderate levels.

Shortly after 04:00 UTC on December 21, solar wind speeds increased to just over 500 km/s, and eventually increased to over 600 km/s over the next couple of hours. Bz values began to vary, fluctuating between +/- 11 nT. 

Geomagnetic K-index of 5 (G1 Minor geomagnetic storm) threshold was first reached at 16:06 UTC. Just a couple of minutes later, at 16:13 UTC, G2 Moderate level conditions were reached.

Solar wind parameters are expected to remain enhanced through December 23 as a positive polarity, northern extension, CH HSS continues to influence the solar wind parameters.

Conditions are expected to begin a slow return to mostly unsettled to active levels on December 23.

Credit: NASA SDO/AIA

Meanwhile, solar activity is at very low levels and is expected to remain like that, with a slight chance for C-class flares, for the next three days (December 21 – 23).

There is only one numbered active region on the Earth side of the Sun – AR 2620 (beta). The region exhibited growth and separation between the leader and trailer spots over the past 24 hours, yet remained inactive.

Featured image credit: NOAA/SWPC