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Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2018 Aug 22 1230 UTC

SIDC Forecast

Brillamenti solari

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Minor storm expected (A>=30 or K=5)

Protoni solari

Quiet

	10cm flux	Ap
22 Aug 2018	068	017
23 Aug 2018	068	017
24 Aug 2018	068	038

Bulletin

Solar activity was very low with X-ray flux below B level throughout the period. The only region on disk (NOAA AR 2719) is in decay and X-ray flux is expected to remain below C level.

Reanalysis of the CME of August 20, which was reported yesterday, shows an additional CME front extending over the South. The angular width of the CME is thus much larger than initially analysed and although faint, it could be classified as partial halo CME. Together with the location of the associated filament eruption it is thus likely that a component is Earth- bound. With an uncertain speed of between 300 and 500 km/s an arrival is anticipated between noon of August 24 and noon of August 25. No additional new CME onsets were observed in coronagraphic data.

Solar proton flux is at background levels and expected to remain so.

Solar wind speed has decayed from just under 600 km/s to around 450 km/s currently, while total magnetic field was nominal between 2-5nT. It thus seems that the influence of the Southern negative polarity coronal hole is fading more rapidly than initially anticipated. Solar wind conditions may, however, become enhanced again with later today still a small possibility of a shock related to the August 19 CME and from noon august 24 onwards the possible arrival of the August 20 CME. Effects in terms of solar wind speed should be small but the magnetic field may see significant effects of the passing cloud.

Geomagnetic conditions were quiet to unsettled (both K Dourbes and NOAA Kp 1-3) and are initially expected to remain so. Should the August 20 CME carry significant Southward magnetic field, minor geomagnetic storms are possible from noon August 24 onwards.

Today's estimated international sunspot number (ISN): 000, based on 15 stations.

Solar indices for 21 Aug 2018

Wolf number Catania	///
10cm solar flux	068
AK Chambon La Forêt	012
AK Wingst	008
Estimated Ap	008
Estimated international sunspot number	016 - Based on 29 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

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