Solar activity was high. An X3.4 flare from an apparent east limb source occurred at 28/2045 UTC, and remained in progress at the end of the period. This event was accompanied by bright loops visible in h-alpha imagery behind the east limb near S27. A fainter prominence was also visible on the northwest limb near the approximate location of Region 9742 (N12W94), but the lack of subsequent energetic particle enhancements seems to favor the east limb source. Other activity included an impulsive M4/Sf from Region 9742 at 28/0351 UTC, and weaker M-class events from Regions 9748 (S11W76) and 9754 (S08W02). Two new regions were numbered today: 9764 (N12E15) and 9765 (N05E77).

Solar activity is expected to remain moderate to high for the next three days.

The geomagnetic field was quiet to unsettled. The greater than 10 MeV proton event which had been in progress since 26 December ended today. The event began at 26/0605 UTC, reached a maximum flux of 779 pfu at 26/1115 UTC, and ended at 28/1040 UTC.

The increase in geomagnetic field activity, which had been expected for today, has not yet occurred, but precursors in solar wind data from the ACE satellite suggest that a shock arrival may still yet occur, perhaps within the next 10 hours or so. Uncertainty in the earthward speed of shock propagation from the CME event of 26 December is a likely cause for the delay, though this event could also miss the Earth. Unsettled to minor storm conditions, and isolated major storms conditions at higher latitudes, remain possible within the first day of the forecast period. Predominantly quiet to unsettled conditions are expected thereafter.

  觀測的       28 Dec 263
  預測的   29 Dec-31 Dec  260/255/255
  90天平均值        28 Dec 218

  觀測的 Afr/Ap 27 Dec  010/006
  估算值     Afr/Ap 28 Dec  012/010
  預測的    Afr/Ap 29 Dec-31 Dec  025/030-012/015-008/010