:Product: Weekly Highlights and Forecasts :Issued: 2004 Jul 13 2212 UTC # Prepared by the US Dept. of Commerce, NOAA, Space Environment Center # Product description and SEC contact on the Web # http://www.sec.noaa.gov/weekly.html # # Weekly Highlights and Forecasts # Highlights of Solar and Geomagnetic Activity 05 - 11 July 2004 Solar activity was very low to low. Activity levels for the first six days of the summary period were very low. Region 639 (N13, L=249, class/area, Cao/150 on 29 June) produced several B-class flares on 05 July. A large halo CME was visible on LASCO imagery on 06 July. This was just one of several CMEs to originate from behind the solar disk. The likely source of these CMEs was old Region 635 (S11, L=055), which rotated around the west limb on 27 June with a moderately complex magnetic configuration. Very low conditions persisted from 08 – 10 July with developing Region 642 (S07, L=124, class/area, Cao/130 on 11 July) producing occasional B-class flares. Bright x-ray emissions and CME activity were observed off the southeast limb on 10 July indicating that a volatile active region was rotating into view. The period ended at low levels with several C-class flares occurring from this active region on the SE limb. At the time of this writing, M-class events were observed from activity on the SE limb and a rapidly developing region near N13W53. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft during most of the summary period. The period began with the solar wind speed slightly elevated to approximately 450 km/s, but gradually decreased to near 300 km/s by 08 July. A sector boundary crossing was observed to occur early on 09 July. Total B field, which was less than 5 nT prior to the sector change, gradually increased to over 15 nT by 11 July. A coronal hole high speed stream was preceded by co-rotating interaction region (CIR) late on 10 July. Solar wind speed gradually increased to over 500 km/s through the end the period. IMF Bz was generally in the +5 to –5 nT range until after the sector crossing on 9 July. Bz was predominantly southward following the sector change with periods over -10 nT late on 11 July. There were no greater than 10 MeV proton events at geo-synchronous orbit during the summary period. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels for a brief period on 05 July. The geomagnetic field ranged from quiet to active. The first five days of the summary period were dominated by mostly quiet geomagnetic field conditions with isolated high latitude unsettled periods. The onset of the CIR on 10 July resulted in occasional active periods at all latitudes. Forecast of Solar and Geomagnetic Activity 14 July - 09 August 2004 Solar activity is expected to range from low to high levels. Mostly moderate to high level activity is expected early in the period from active regions in both the northwest and southeast solar quadrants. The complex active regions currently on the visible disk at the time of this writing have potential to produce moderate to high levels of activity until 24 July. Backside SOHO MDI imagery also indicate that one or more complex regions will rotate onto the visible on 17 – 18 July. Consequently, moderate or even isolated high activity levels are possible during the latter half of the forecast period. A greater than 10 MeV proton event is possible. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 26 – 27 July due to a recurrent coronal hole high speed stream. The geomagnetic field is expected to range from quiet to active levels with minor storm periods at high latitudes. Unsettled to active conditions with high latitude minor storm periods are possible on 16 –17 July due to possible CME effects, and again on 25-26 July as a recurrent coronal high speed stream rotates into a geoeffective position.