Space Weather Forecast Headline: Minor/Moderate geomagnetic storm Expected Monday 17 August.

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Activity increased to Low, with a long-period Common-class flare from a sunspot region on the southwest of the Sun peaking at 14/0701UTC. This flare was associated with a burst of energy in the radio spectrum and a CME which has been analysed as missing Earth. Another Common class flare peaked at 14/2155 UTC, from a region in the northeast.

There are currently up to seven sunspot regions on the Earth-facing side of the Sun. The largest, and moderately magnetically complex, region is now approaching the central solar meridian and has shown continued slight growth and consolidation of small spots in the trailing portion, and also within the penumbra of the leader spot. But this region did not generate the Common class flares. Instead they came form one of the remaining regions on the disc, which are generally small, mostly magnetically simple, and weak.

A large 'filament' (arc of plasma) forming a U-shape around a centre near S10E020 lifted off the Sun from around 14/0400UTC. The ejecta was visible on extreme UV satellite imagery as visibly intersecting the Sun-Earth line. Assessment of this CME suggests a most likely arrival time during the first half of the UTC day of Monday 17 August.

Solar Wind / Geomagnetic Activity: Solar winds remained at background levels, peaking at 392 km/s at 14/0251 UTC. The strength of the solar winds magnetic field was weak, as was the north-south component which was erratic in character, with a slight bias towards being southward (usually to greater geomagnetic effect).

The net result of the above solar wind measures was for Quiet to Unsettled geomagnetic activity.

Energetic Particles / Solar Radiation: No solar radiation storms were observed, with no enhancement tied to increased western solar hemisphere x-ray activity.

Four-Day Space Weather Forecast Summary

Solar Activity: Activity will most likely remain low, however there is now a daily slight chance of Moderate-class flares. New regions may rotate onto the disc during the forecast period, most likely during Day 1 (15th Aug) and then Day 4 (18th Aug), although these regions are unlikely to be significant due to the lack of activity from behind the east limb.

Solar Wind / Geomagnetic Activity: There is one Earth directed CME in the forecast, from the filament eruption on the 14th. The timing of the CME arrival has uncertainties linked to the potential arrival of a solar wind enhancement from a coronal hole feature in the northwest. This solar wind enhancement is expected to connect to Earth through Day 1 (15th Aug) but there is an increasing probability that the connection will not occur. Without being embedded within a solar wind enhancement the CME arrival will be later than currently expected. Late day 4 (18th Aug) a new solar wind enhancement may arrive, from a coronal hole currently in the southeast. However, this feature may be too far south to connect to Earth.

Energetic Particles / Solar Radiation: Solar radiation levels showed no measurable reaction to increased activity from the sunspot region in the southwest. There is a daily slight chance of Minor Solar Radiation Storm S1 or greater, revised slightly higher than of late in light of increased activity.