Solar activity was low. The largest event of the period was a C4/1f flare from Region 125 (S08E55). An associated Type II radio sweep and CME was observed with this flare, but the ejecta was not earthward directed. Region 119 (S14W10) produced occasional low C-class flares. This region continues to develop and a weak delta configuration is now evident. Region 105 (S08W83) also produced minor C-class flares as it rotates around the west limb. New Region 126 (S23E75) was numbered today.

Solar activity is expected to be low to moderate. Developing Region 119 has best potential for a low M-class flare. There is still a small chance for a low M-class flare from Region 105 on the west limb.

The geomagnetic field ranged from quiet to minor storm levels. A weak shock was observed at the ACE spacecraft just before 19/0600Z. Solar wind speed gradually increased to over 750 km/s by late in the period, but total magnetic field measurements and densities remained very low. This disturbance is likely associated with the C8 flare and CME observed on 17 September. The greater than 2 MeV electron flux was at moderate to high levels.

The geomagnetic field is expected to continue at unsettled to minor storm levels through day one. Unsettled conditions are expected to prevail after the current disturbance subsides.

  觀測的       19 Sep 165
  預測的   20 Sep-22 Sep  165/160/155
  90天平均值        19 Sep 178

  觀測的 Afr/Ap 18 Sep  013/014
  估算值     Afr/Ap 19 Sep  018/018
  預測的    Afr/Ap 20 Sep-22 Sep  020/020-008/010-008/010