Solar activity was moderate. Region 226 (S18W01) produced an M1.9/1n flare at 16/2255 UTC. This region has continued to grow in size and complexity, and appears to contain a magnetic delta configuration in its intermediate spots. Shortly following the aforementioned flare, Region 227 (N07W20) produced a subfaint optical flare that corresponded with an impulsive M1.3 x-ray enhancement at 16/2336 UTC. Other flare activity included several C-class events from the regions noted above as well as Region 225 (N17E11). New Region 230 (S08E59) was numbered today.

Solar activity is expected to be low to moderate for the next three days. A slight chance for an isolated major flare event is possible, particularly from Region 226.

The geomagnetic field was quiet, with one isolated unsettled period at higher latitudes during 17/1500-1800 UTC.

The geomagnetic field is expected to be quiet to active during day one of the forecast period, and predominantly active with isolated storming intervals possible during the remainder of the period, due to the expected onset of recurrent coronal hole effects.

  觀測的       17 Dec 213
  預測的   18 Dec-20 Dec  205/205/195
  90天平均值        17 Dec 165

  觀測的 Afr/Ap 16 Dec  003/008
  估算值     Afr/Ap 17 Dec  004/010
  預測的    Afr/Ap 18 Dec-20 Dec  015/015-020/035-018/025