Solar alert

Issued on 2023 Dec 15 0901 UTC

A halo coronal mass ejection (CME) was observed in LASCO/C2 coronagraph data from 17:24 UTC on December 14, as an initial estimate the projected speed is over 1000 km/s. The CME is associated with a X2.8 flare, originating from NOAA AR 3514, along with a Type II and Type IV radio burst. The CME is directed primarily to the West from the Earth perspective. Analysis of the CME is ongoing, but due to the location of the CME origin, a glancing blow to the Earth's environment can be possible from late on December 16. The greater than 10 MeV proton flux levels have been slightly elevated related to this event but have remained below radiation storm thresholds. Note also that the 13-21MeV proton flux as measured on board STEREO-A has risen, most probably in association to this event.

Issued on 2023 Dec 15 1237 UTC

A shock was observed in ACE data at 10:57 UTC on December 15. The magnetic field jumped from 5 to 18 nT, and the solar wind speed from 280 to 430 km/s. It is not clear which of the events from the past days is responsible for this shock arrival, but it may be associated to the faint partial halo CME observed on December 13, that was expected for later today. Geomagnetic conditions are going to be disturbed in the next 24 hours. Depending on the Bz orientation, active to minor storm levels can be expected.

Issued on 2023 Dec 15 1855 UTC

A partial halo Coronal Mass Ejection (CME) was first observed in the SOHO/LASCO-C2 field of view at 07:48 UTC on December 15. The CME is likely associated with an M6.3 and an M6.9 flare, which peaked at 07:15 UTC and 07:34 UTC on December 15th, originating from NOAA AR 3514, along with a Type IV radio burst. The CME is directed primarily to the South-West from the Earth’s perspective and the bulk of the CME is not expected to be Earth directed. However, a shock arrival cannot be fully excluded. Further analysis is on-going to better determine the expected impact.

Reference for this alert

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