Solar activity was at low levels. Region 226 (S28W54) produced most of today's observed activity, a C4.6/1f occurring at 21/0453 UTC was the largest flare during the period. The beta-gamma-delta magnetic structure remains intact although much decay was noted in spot groups areal coverage today. Region 229 (N19W29) continues to show steady decay and was fairly quiescent today. Region 230 (S08E06) underwent little change but remains a beta-gamma magnetic complex. Region 232 (N13W08) was newly assigned today.

Solar activity is expected to be at low to moderate levels. Regions 226 and 230 are capable of producing M-class flare activity.

The geomagnetic field was predominantly at quiet to active levels as the geoeffective coronal hole high speed stream wanes. Middle and high latitudes experienced storming conditions between 21/0300 and 0600 UTC.

The geomagnetic field is expected to be at active to minor storm levels for day one of the forecast period. The CME from the M2.7 flare late on 19 December is expected to arrive early to mid-day on 22 December. Predominantly quiet to unsettled conditions are expected on days two and three.

  觀測的       21 Dec 184
  預測的   22 Dec-24 Dec  185/180/180
  90天平均值        21 Dec 167

  觀測的 Afr/Ap 20 Dec  012/016
  估算值     Afr/Ap 21 Dec  015/018
  預測的    Afr/Ap 22 Dec-24 Dec  025/025-012/015-006/010