Global geomagnetic conditions escalated to moderate storm levels (NOAA Kp 6+ ) between 21:00 UTC on December 10 and 00:00 UTC on December 11 and are currently at quiet levels (NOAA Kp 2 + ). Locally, geomagnetic conditions reached moderate storm levels (K BEL 6) between 23:00 UTC on December 10 and 01:00 UTC on December 11. The geomagnetic storm was likely the result of a glancing blow arrival associated with the Coronal Mass Ejection (SIDC CME 607) observed on December 8. An increase in solar wind parameters was observed around 20:00 UTC on December 10. Solar wind speeds rose from approximately 400 km/s to 450 km/s, and the interplanetary magnetic field strength increased from 2 nT to 18 nT. From 20:00 UTC on December 10 to 02:00 UTC on December 11, there was a prolonged interval of negative Bz, with values reaching a minimum of –16 nT. Further minor to moderate geomagnetic storm conditions remain possible in the coming hours.

Solar flaring activity was low over the past 24 hours, with only C-class flares. The strongest flare was a C3.5 flare (SIDC Flare 6409) peaking at 15:58 UTC on December 12. It was associated with SIDC Sunspot Group 712 (NOAA Active Region 4294), which has since rotated across the west limb. There are currently six numbered active regions on the solar disk. SIDC Sunspot Groups 722, 723 (NOAA Active Regions 4307, 4308) are the most complex Groups, with magnetic type beta-gamma. SIDC Sunspot Group 724 (magnetic type alpha) has emerged near the center of the disk. SIDC Sunspot Groups 687 (NOAA Active Region 4299) has decayed into a plage. The solar flaring activity is expected to be low over the next 24 hours, with C-class flares very likely and a chance for M-class flares. A prominence eruption was observed in AIA 304 data around 00:30 UTC on December 12, at the southeast limb. An associated slow, wide CME (SIDC CME 609) was observed in LASCO/C2 coronagraph imagery starting around 04:00 UTC on December 12, lifting off from the southeast limb. It is not expected to impact Earth. No other Earth-directed CMEs were observed in the available coronagraph imagery. The greater than 10 MeV proton flux was below the 10 pfu threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours. The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was below the 1000 pfu threshold in the last 24 hours. The greater than 2 MeV electron flux is expected to be below the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours.

Geomagnetic conditions globally were mostly at quiet to unsettled levels (NOAA Kp 2 to 3), with an interval of minor storm conditions (NOAA Kp 5) between 18:00 UTC on December 12 and 03:00 UTC on December 13. Locally, geomagnetic conditions were mostly at quiet to active levels (K BEL 2 to 4), with an interval of minor storm conditions (K BEL 5) between 18:00 UTC and 20:00 UTC on December 12. Further minor to moderate geomagnetic storm conditions remain possible over the next 24 hours due to the continued influence of the high-speed stream. Over the past 24 hours, solar wind parameters (ACE) were enhanced, most likely due to the influence of the high-speed stream from the negative polarity coronal hole (SIDC Coronal Hole 142) and the ongoing influence of an ICME arrival. Speed values increased from around 400 km/s to around 600 km/s. The interplanetary magnetic field values varied between 6 nT and 16 nT. The Bz component varied between -14 nT and 15 nT. The interplanetary magnetic field angle was mostly in the negative sector. Enhanced solar wind conditions are expected to persist over the next 24 hours due to the continued influence of the high-speed stream.