Solar activity reached high levels. A total of five M-class flares were observed this period. Region 137 (S19W20) was the primary source for this activity, producing four M-class flares, the largest being an M4/1n at 04/0538Z. A delta configuration was observed to develop in this region late yesterday, and the region exhibited frequent flare activity since. Region 139 appears to be growing quickly as it rotates into view. This region produced an M1/1f flare with associated Type II sweep (357 km/s) at 04/1255Z, and also produced several moderate C-class flares. A delta configuration is obvious and white light areal coverage is nearing 500 millionths. New Region 140 (S07E76) was numbered today.

Solar activity is expected to be at moderate to high levels. Complex Regions 137 and 139 will continue to produce M-class activity, with increasing likelihood for a major flare from Region 139 as it continues to develop.

The geomagnetic field was at predominantly active to major storm levels with an isolated severe storm period between 04/00 - 03Z. Though solar wind speed remains below 450 km/s, the Bz component of the interplanetary magnetic field was sustained southward for the entire period, ranging from -2 to -12 nT. The storm was gradually subsiding by the end of the period.

The geomagnetic field is expected to range from unsettled to minor storm levels with isolated major storm periods possible. Transient effects from CMEs observed early on 3 Oct and again on 4 Oct will likely enhance the disturbed periods on days two and three. A large, recurrent southern coronal hole will move into geoeffective position late on day three.

  觀測的       04 Oct 158
  預測的   05 Oct-07 Oct  160/170/180
  90天平均值        04 Oct 179

  觀測的 Afr/Ap 03 Oct  022/033
  估算值     Afr/Ap 04 Oct  035/045
  預測的    Afr/Ap 05 Oct-07 Oct  018/020-015/020-012/015