Solar activity was high. Region 720 (N13W30) continued to produce flare activity with the largest being an X3/2f at 17/0952 UTC. This flare was associated with a complex full-halo CME directed mostly towards the northwest. Although this region remains large and magnetically complex some restructuring of the sunspots was apparent following this flare. New Region 723 (N06E77) is rotating around the east limb.

Solar activity is expected to remain at high to very high levels. Region 720 could produce yet another major solar event.

The geomagnetic field ranged from quiet to severe storm levels. Solar wind conditions observed by the NASA ACE spacecraft show a fairly complex onset of activity which may suggest the arrival of a solar wind structure from combined CMEs expected from previous major flares on 15 January. The proton event at greater than 10 MeV that began on 16/0210 UTC remains in progress. The latest X3 flare discussed in Part IA has increased the current peak flux to 5040 pfu observed at 17/1750 UTC. A proton event at greater than 100 MeV also resulted from the X3 flare, beginning at 17/1215 UTC and with a current peak flux of 28 pfu observed at 17/1700 UTC. The greater than 2 MeV electron flux observed by the GOES spacecraft, as well as the solar wind parameters observed by the ACE SWEPAM instruments, have been rendered temporarily unusable due to the energetic proton event.

The geomagnetic field is expected to continue at major to severe storm levels. Another CME arrival is expected late on 18 January, or possibly early on 19 January, due to today's X3 flare, which should keep geomagnetic activity levels elevated. The current proton events are expected to remain in progress.

  Observé       17 Jan 138
  Prévisionnel   18 Jan-20 Jan  135/130/120
  Moyenne des 90 derniers jours        17 Jan 107

  Observé Afr/Ap 16 Jan  010/012
  Estimé     Afr/Ap 17 Jan  060/080
  Prévisionnel    Afr/Ap 18 Jan-20 Jan  060/080-050/050-030/030