Solar activity was high. Region 540 (S14W22) produced an M6/2n flare at 20/0743Z. Radio bursts associated with this flare included a 4500 sfu burst on 245 MHz and Type II sweep with a shock speed of 950 km/s. A CME was visible on LASCO imagery. Region 540 also produced an impressive long duration C5 flare that occurred between 19/2202Z through 20/0229Z, peaking at 20/0045Z. A full halo CME was observed with this event. Soon after the eruption in Region 540, segments of the large circular filament in the northwest quadrant also erupted. Region 540 maintains a weak delta configuration in its trailing spots, but further decay in total area was also noted. The trailing spots in Region 542 (N10W03) have been identified as a separate region and were numbered as Region 544.

Solar activity is expected to be low to moderate. Though in decay, Region 540 still maintains potential for isolated M-class flares. The remaining three spot groups on the visible disk have potential for C-class activity.

The geomagnetic field was quiet to active. Solar wind speed is in gradual decline as a large transequatorial coronal hole rotates out of a geoeffective position. Solar wind speed decreased to near 500 km/s, but periods of southward Bz generated occasional active periods. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels again today.

The geomagnetic field is expected to range from quiet to major storming over the next three days. Quiet to active periods are expected on 21 January. The full halo CME observed on LASCO imagery at 20/0006Z will likely impact the geomagnetic field early on 22 January. Active to major storm periods are possible. Unsettled to active conditions are expected on January 23 as the storm subsides.

  Observé       20 Jan 129
  Prévisionnel   21 Jan-23 Jan  130/130/130
  Moyenne des 90 derniers jours        20 Jan 138

  Observé Afr/Ap 19 Jan  010/017
  Estimé     Afr/Ap 20 Jan  018/022
  Prévisionnel    Afr/Ap 21 Jan-23 Jan  012/015-035/045-015/025