Solar alert

Issued on 2021 Aug 27 0719 UTC

The in situ data indicate arrival of the shock wave most probably associated with the expected arrival of the partial halo CME (first observed in the SOHO LASCO C2 field of view at about 06:00 UT on August 23rd). The sudden increase of the solar wind speed, density, temperature and interplanetary magnetic field magnitude was observed at about 00:25 UT on August 27. The arrival of the shock wave induced unsettled geomagnetic conditions.

Issued on 2021 Aug 27 0859 UTC

The halo CME, associated with the long duration C3.0 flare from the Catania sunspot group 33 (NOAA AR 2859), was first observed in the SOHO LASCO C2 field of view at about 19:00 UT on April 26. The CME had angular width of about 290 degrees and projected line of the sight speed of about 530 km/s (as reported by the CACTUS software). This CME might arrive to Earth in the morning of August 30.

Issued on 2021 Aug 27 2019 UTC

The in situ data show that the arrival of the shock wave this morning was followed by arrival of its driver ICME. During last eight hours the continuously negative Bz component (down to - 15 nT) was observed, inducing the active geomagnetic conditions. Presently both, local station at Dourbes and NOAA reported K and Kp equal to 4. However, further decrease of the Bz component, or increase of the solar wind speed can result in the K and Kp index equal to 5 or higher.

Reference for this alert

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