Solar activity reached high levels this period. Region 540 (S14E15), the source of several low C-class flares throughout the period, produced an M5 flare at 17/1750Z. Moderate to strong radio bursts accompanied this flare, including a 580 sfu Tenflare and an extraordinary 270,000 sfu burst on 245 MHz (observed at both Sagamore Hill and Palehua observatories). A Type II radio sweep (784 km/s) was also observed. Region 540 is a moderate size group of approximately 350 millionths of white light areal coverage with minor magnetic mixing. Region 537 (N04W70) continues in a slow decay phase as it approaches the west limb. Isolated C-class activity was observed from this region. No other significant activity was noted.

Solar activity is expected to be low to moderate. Isolated M-class activity is possible from Region 540.

The geomagnetic field was quiet to active. A coronal hole high speed stream is responsible for the weak disturbed periods. The IMF Bz was predominantly northward which offset the geomagnetic effects of the high speed flow. The greater than 2 MeV electron flux at geosynchronous orbit was at high levels today.

The geomagnetic field is expected to continue at quiet to active levels through 18 January as the high speed stream subsides. Quiet to unsettled conditions are expected on 19 January. A disturbance associated with today's M5 flare, is expect to begin on 20 January. Active to minor storm conditions are expected.

  Observed       17 Jan 123
  Predicted   18 Jan-20 Jan  125/120/110
  90 Day Mean        17 Jan 139

  Observed Afr/Ap 16 Jan  021/026
  Estimated     Afr/Ap 17 Jan  015/016
  Predicted    Afr/Ap 18 Jan-20 Jan  015/015-010/012-020/020