Solar activity was at moderate levels. Region 9661 (N14W64) produced an M2/2n flare at 21/1136 UTC with associated discrete frequency radio bursts. Analysis in white light of this region also shows a re-emergence of the delta magnetic configuration. An optically uncorrelated M1 flare was observed at 21/0518 UTC and an associated Type II radio sweep with a shock velocity of 536 km/s. Using SXI imagery it would appear that this flare had occurred in Region 9670 (S18E06). Several C-class flares were produced from Region 9674 (S09E07) during the period.

Solar activity is expected to be at moderate to high levels. Regions 9661 and 9670 remain capable of producing M-class or isolated major flares.

The geomagnetic field ranged from quiet to major storm levels. A strong shock was observed at ACE at 21/1614 UTC. This was followed by a sudden impulse at 21/1645 UTC (measured as 15 nt on the Boulder magnetometer). The sudden impulse was followed by minor (21/1500-1800 UTC) and major (21/1800-2100 UTC) storm levels. BZ was predominantly negative since the arrival of shock up until the time of issue of this bulletin.

The geomagnetic field is expected to be at active to major storm levels. The full halo CME from the X1/2b flare that occurred at 19/1630 UTC from Region 9661 is expected to arrive on the middle of day one of the forecast period.

  觀測的       21 Oct 224
  預測的   22 Oct-24 Oct  225/225/215
  90天平均值        21 Oct 191

  觀測的 Afr/Ap 20 Oct  008/010
  估算值     Afr/Ap 21 Oct  025/030
  預測的    Afr/Ap 22 Oct-24 Oct  030/035-015/020-012/015