Solar alert

Issued on 2021 Mar 20 1105 UTC

The fast flow associated with the extension to the southern polar Coronal Hole, which crossed the central meridian on Mar 17, has now arrived. The solar wind speed has increased up to the current value of 540 km/s, and the Bz component of the interplanetary magnetic field became predominantly negative from 05 UT, with a minimum value of -20 nT. This rather strong southward field concurrent with the fast solar wind produced geomagnetic storm, NOAA reported Kp=6 and local stations at Dourbes reported K=5. The high speed stream is expected to persist until Mar 22 and further minor to moderate geomagnetic storms can not be excluded, especially if Bz component remains negative for long period of time.

Reference for this alert

All Presto solar alerts