Solar activity was at low levels due to a few C-class events from Region 1112 (S20W44), the largest a C1.7 x-ray event observed at 17/0859Z. The region continued to evolve over the past 24 hours, increasing in both area and extent, while maintaining Beta-Gamma magnetic characteristics. New Region 1116 (N22W14) was numbered as a simple bi-polar spot group.

Solar activity is expected to be at very low to low levels all three days of the forecast period (18 - 20 October), with a chance for M-class events from evolving Region 1112.

The geomagnetic field ranged from quiet to minor storm levels during the period. Activity was at quiet to unsettled levels until about 17/0700Z when the field became disturbed. Geomagnetic activity increased to active to minor storm levels through 17/0900Z, returning to mostly quiet levels through the remainder of the period. At about 17/0400Z, signatures at the ACE satellite indicated gradual increases in temperature, density and wind velocity. The Bz component of the interplanetary magnetic field (IMF) turned southward, and remained south for about 7 hours, reaching a maximum deflection of -7nT at 17/0737Z. The Bt component of the IMF reached a maximum of 10nT at 17/0520Z. This short-lived disturbance is thought to have been a result of a glancing blow from the slow-moving CME observed on 10 October.

The geomagnetic field is expected to be at quiet to active levels all three days of the forecast period (18 - 20 October). Isolated minor storm periods are possible on 19 October. A coronal hole high speed stream (CH HSS) is expected to rotate into a geoeffective position late on 18 October, followed by a second geoeffective CH HSS likely to arrive early on 20 October. These features, coupled with possible effects from the CME observed on 14 October, expected to arrive on 19 October, are the reasons for the forecasted increase in geomagnetic activity.

  Наблюдаемый       17 Oct 084
  Прогнозируемый   18 Oct-20 Oct  086/086/086
  среднее значение за последние 3 месяца        17 Oct 081

  Наблюдаемый Afr/Ap 16 Oct  003/006
  По оценкам     Afr/Ap 17 Oct  009/013
  Прогнозируемый    Afr/Ap 18 Oct-20 Oct  008/010-012/012-008/010