Geomagnetic storm reaching G3 (Strong) levels in progress, extreme conditions possible [1]

During the last 24 hours, solar wind parameters, measured by the ACE spacecraft, were indicative of background solar wind conditions until 07:45 UTC on August 15, when a sudden impulse occurred due to the arrival of a co-rotating interaction region (CIR) ahead of a recurrent positive polarity coronal hole high speed stream (CH HSS), SWPC reported at 12:30 UTC today.

Solar wind speeds jumped from near 350 km/s to near 500 km/s. IMF total field strength jumped from 11 nT to as high as 28 nT, while the maximum southward deflection of the Bz component was -20 nT.

Geomagnetic storm reached G1 (Minor) conditions at 11:25, G2 (Moderate) at 11:32 and G3 (Strong) at 11:43 UTC.

Additionally, a partial halo Coronal Mass Ejection (CME) produced by the solar filament eruption at 13:32 UTC on August 12 is expected to arrive early August 16. This is expected to further contribute to the already enhanced conditions.