Solar activity was moderate. Activity in the vicinity of Region 9866 (S09W46) was associated with a long duration M1 flare which began at 0216 UTC and ended at 0400 UTC. Also associated with this event were a type IV sweep and a halo CME visible in LASCO imagery. Region 9866 continues to decay slowly. C-class flare activity was observed from Region 9870 (S20W39) which appears to have some new, opposite polarity flux emergence. Region 9871 (S19E07) produced a C8/1f flare at 1918 UTC and is currently the largest region on the disk.

Solar activity is expected to be moderate. Regions 9866 and 9871 are considered to be the most likely sources for M-class flares. There is a slight chance for a major flare during the next three days.

The geomagnetic field was quiet until 1323 UTC when a strong sudden impulse (SI) was observed. The SI measured 42 nT on the Boulder magnetometer. The SI followed the passage of a shock at ACE at 1237 UTC. The post shock flow at ACE consisted of enhanced magnetic fields but so far they have been predominantly northward. Geomagnetic activity subsequent to the SI has been unsettled to active. The greater than 10 MeV proton event that began at 17/0820 UTC officially ended at 17/1230 UTC, but flux levels remained enhanced thereafter. With the arrival of the shock the protons once again reached event level, beginning at 19/1300 UTC. The maximum flux observed so far was 25 PFU at 19/1535 UTC.

The geomagnetic field is expected to be mostly active for the next 24 hours, with a chance for some isolated minor storm periods. After the current transient flow subsides there should be a lull in activity, but another shock is expected to arrive near mid-day (UT time) on the 20th in response to today's halo CME. Activity following this shock is expected to be mostly active. Conditions should subside to unsettled sometime on the third day. The greater than 10 MeV proton event is likely to end sometime in the next 12 hours.

  觀測的       18 Mar 178
  預測的   19 Mar-21 Mar  180/175/175
  90天平均值        18 Mar 214

  觀測的 Afr/Ap 17 Mar  002/004
  估算值     Afr/Ap 18 Mar  015/012
  預測的    Afr/Ap 19 Mar-21 Mar  020/020-020/020-015/015