Solar activity was high. Region 1548 (N19E86) produced an M5/Sf flare at 18/0102Z, accompanied by a Tenflare (150 pfu). An M1/Sn flare from the same region followed at 18/0323Z, also accompanied by a Tenflare (120 pfu). Finally, an M2/1N occurred at 18/1607Z. Several coronal mass ejections (CMEs) were observed in the past 24 hours, none appear to have a geoeffective component. SDO 304 imagery showed a filament eruption in the vicinity of Region 1543 (N23W74) around 17/16Z. A CME was subsequently observed in LASCO C2 coronagraph imagery at 17/1836Z, and in LASCO C3 imagery at 17/1918Z. A second filament eruption and CME was observed near Region 1543 between 17/22Z and 18/0034Z. It was visible in STEREO-B COR2 imagery at 18/0110Z and in LASCO C3 imagery at 18/0454Z. This CME was directed well north of the ecliptic.

Solar activity is expected to be low with moderate activity likely for the next three days (19-21 August).

The geomagnetic field was quiet to active. Solar wind speed at the ACE spacecraft ranged between about 350-420 km/s during the period. The Bz component of the interplanetary magnetic field ranged between -8 and +12 nT. Solar wind density at ACE increased sharply after 18/19Z. The geomagnetic field reached active levels during the last period (18-21Z) coincident with a change to the positive sector and the arrival of the corotating active region.

The geomagnetic field is expected to be quiet to unsettled for the next three days (19-21 August) as a corotating interaction region and coronal hole high speed stream become geoeffective.

  Observé       18 Aug 097
  Prévisionnel   19 Aug-21 Aug  100/100/100
  Moyenne des 90 derniers jours        18 Aug 125

  Observé Afr/Ap 17 Aug  011/011
  Estimé     Afr/Ap 18 Aug  009/011
  Prévisionnel    Afr/Ap 19 Aug-21 Aug  010/012-011/012-007/008