Space Weather Forecast Headline: Minor/Moderate (R1/2) radio blackouts likely.

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Activity was Moderate, peaking into the start of the UTC day with Moderate-class flare activity forming part of the declining limb of an earlier Strong-class flare (peaking 19/2350UTC) from the largest and most complex region on the facing side of the Sun in the northwest.

There are six sunspot regions facing Earth at present. The largest and most complex region, showed a decrease in area throughout, with several of its intermediate spots fading entirely to give a more open character. A group to its immediate east was largely unchanged, as were the magnetically unipolar regions in the western solar hemisphere. In the southeast, part of a pair of regions moved rapidly westwards in close proximity to the other, perhaps prompting or marking instability in this southeastern part of the Sun.

The main Coronal Mass Ejections (CMEs) observed in the period were a slow but large 'prominence eruption' (arc of plasma from the Sun's edge) from the southwestern solar horizon around 20/0600UTC and a CME associated with a Moderate-class flare from the vicinity of a sunspot region in the southeast at 20/1739UTC. Neither event appears to have an Earth-directed component, and no new CMEs were therefore evident in available satellite imagery.

Solar Wind / Geomagnetic Activity: Solar winds suggested an ongoing fast wind from a coronal hole on the southwest of the Sun.

The solar wind speed showed a rise and fall through elevated territory. The number of particles in the solar wind was within background, while the magnetic field fell slightly from slightly elevated levels to background, with an erratic north-south component.

The net result of the above solar wind measures was for provisionally quiet geomagnetic activity throughout.

Solar Radiation: No solar radiation storms were observed.

Four-Day Space Weather Forecast Summary

Solar Activity: Solar activity is forecast to be Moderate, with isolated Moderate-class flares likely, and a slight chance of rising to high with further isolated Strong-class flares. This risk may fall slightly at the end of the four days due to the departure of the largest and most active sunspot region.

Solar Wind / Geomagnetic Activity: The 17 June CME is now overdue and has likely missed if not very soon evident. No further CMEs are expected.

The forecast otherwise comprises possible further marginal influence from a coronal hole fast wind, before a more intense feature perhaps arrives at the very end of the four days.

There is a slight chance of Minor Geomagnetic Storm G1 bookending the forecast period as a result of the overdue CME and then a coronal hole fast wind, with more marginal intervening activity from the current, lesser, coronal hole.

Energetic Particles / Solar Radiation: There is a slight chance of Minor Solar Radiation Storm S1 with any notable flares from regions in the western hemisphere.