The event was accompanied by a slow rise in X-ray flux, peaking at C1.6 at 07:11 UTC, as recorded by the Geostationary Operational Environmental Satellite (GOES).
The Large Angle and Spectrometric Coronagraph (LASCO) C2 first detected the CME at 05:00 UTC. Due to the eruption’s location on or just behind the limb, no Earth-directed component is forecast.
Aside from the prominence eruption, overall solar activity remained at low levels over the past 24 hours. Weak C-class flares were observed from plage regions in the northeastern quadrant of the disk.
Three sunspot regions were present, with Region 4187 (S19W00, Dao/beta) being the largest and showing limited leader spot growth. The remaining regions were quiet and stable.
Forecasts suggest solar activity will remain very low to low, with a slight chance of M-class flares through August 22 due to the return of older active regions.
The >2 MeV electron flux remained at normal to moderate levels, while the >10 MeV proton flux was at background levels over the past 24 hours. Electron flux is expected to stay at normal to moderate levels through August 21, driven by coronal hole high-speed stream (CH HSS) influences and possible peripheral effects from the CME that departed the Sun on August 17.
A return to high levels is possible on August 22. Proton flux is expected to remain at background levels through August 22 given the absence of strong active regions.
Solar wind measurements reflected continued influence from a negative-polarity CH HSS. The interplanetary magnetic field ranged between 8–19 nT, while the Bz component briefly deflected southward to values of −7 to −11 nT.
Solar wind speeds increased from ~400 km/s to peaks of ~600–705 km/s before slowly declining toward ~600 km/s after 00:00 UTC.
Disturbed solar wind conditions are forecast to persist through August 22, with possible additional enhancement later on August 20 from glancing effects of the CME launched on August 17.
The geomagnetic field reached G1 – Minor storming levels on August 20 under continued CH HSS influence. G1 storming is likely to persist, with a chance of isolated G2 – Moderate conditions should CME effects add to the disturbance.
Activity is expected to decrease to unsettled or active levels on August 21 and further to quiet to unsettled conditions by August 22 as the high-speed stream influence weakens.