Solar Terrestrial Activity Report Last update August 19, 1999 at 03:45 UTC. Recent development The geomagnetic field was unsettled to minor storm on August 18 under the influence of a coronal stream. Solar wind speed ranged between 510 and 721 km/sec. Solar flare activity was low. Solar flux was 130.7, the planetary A index was 26 (3-hour K indices: 4554 4433, Boulder K indices: 4543 4433). Region 8667 decayed into spotless plage. Region 8668 has minor M class flaring potential. Region 8669 decayed into spotless plage. Region 8671 was quiet and stable but is showing signs of decay. New region 8672 emerged at a moderate pace in the northeast quadrant near the central meridian. The region could start producing C flares today. The resulting SEC/NOAA sunspot number of 47 is the lowest since March 27, 1999. One or more interesting regions are at or approaching the now very bright southeast limb. At least M class flares are possible. Flares and CMEs A total of 6 C class events were observed on August 18 with old region 8662 producing 4 of the events from behind the southwest limb and the region(s) near the southeast limb the origin of at least 1 of the remaining 2 events. The largest event of the day was a C7.8 long duration event from old region 8662. It peaked at 10:43 UTC and triggered a filament eruption which extended well into the southwest quadrant. No terrestrial effects are likely from the accompanying CME. August 17: Region 8668 was the source of a long duration C2.6 event peaking at 13:23 UTC and a very long duration C5.9 event peaking at 16:02 UTC (the event began shortly after 14h UTC). A large coronal mass ejection (visible from 15:08 UTC in LASCO C2) was associated with the latter event, as was the disappearance (eruption) of a huge arched filament near region 8668. The CME became a full halo CME with most of the material heading off to the northeast. Earth will likely receive an impact on August 20 causing the geomagnetic field to become unsettled to minor storm. The background x-ray flux is at the class B8 level. Coronal holes No obvious coronal holes are currently approaching geoeffective positions. Forecast The geomagnetic field is expected to be unsettled to active on August 19 due to a coronal stream, isolated minor storm intervals are possible. Unsettled to minor storm is likely on August 20 following a CME impact. Low frequency (below 2 MHz) radio wave propagation along east-west paths over high and upper middle latitudes is very poor to useless.