:Product: Weekly Highlights and Forecasts :Issued: 2003 Oct 07 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 29 September - 05 October 2003 Solar activity ranged from low to moderate levels. The period began with low level activity on 29 – 30 September with most of the activity originating from Region 464 (N04, L=356, class/area Fki/610 on 26 September). Region 464 maintained a beta-gamma magnetic configuration until it rotated around the west limb. Activity reached moderate levels on 01 October with an M1/1f flare from Region 464 at 0451 UTC. Activity returned to low levels on 02 – 03 October with Region 464 producing a C7/1f flare at 0656 UTC on 02 October and Region 471 (S08, L=222, class/area Eac/210 on 04 October) produced minor C-class flares on 03 October. Region 471 rotated onto the visible disk on 30 September and by 03 October had shown two distinct bipolar magnetic configurations, suggesting two regions. Thus, on 03 October this spot group was split into two distinct regions. Region 473 (S09, L=237, class/area Cso/140 on 04 October) was assigned to the leading spots and Region 471 was assigned the trailing spots. Region 471 developed a beta-gamma configuration on 02 October and maintained this moderate complexity for the remainder of the period. After Region 464 rotated beyond the west limb on 03 October, Region 471 became the source of the majority of flare activity. Moderate level activity was observed on 04 October with an M1/Sf from Region 471 at 1547 UTC. The period ended with numerous B and C-class flares from Region 471 on 05 October. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. The most significant feature in the solar wind during the period was a two day period of elevated solar wind speed. Wind speed increased on 02 October and reached a steady value near 500 km/s on 03 – 04 October. The source of this increased solar wind appeared to be a weak coronal hole. Late on 05 October solar wind began to increase again as a more well defined coronal hole rotated into a geoeffective position. There were no greater than 10 MeV proton events at geosynchronous orbit during the period. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 29 September and again on 02 – 05 October. Geomagnetic activity ranged from quiet to minor storm levels. Activity early in the period, 29 September – 02 October was at quiet to unsettled levels. One period of isolated minor storm conditions was observed on 03 October in connection with the elevated solar wind speed. One period of isolated active conditions were observed on 04 – 05 October. Forecast of Solar and Geomagnetic Activity 08 October - 03 November 2003 Solar activity is expected to range from very low to low levels with a chance of isolated M-class events. Region 471 may keep activity levels somewhat enhanced with isolated M-class events possible. Region 464 is due to return to visible disk on 15 October and may have the potential for isolated M-class activity. No greater than 10 MeV proton events at geosynchronous orbit are expected during the period. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels 07 – 09 October and again on 17 – 26 October. The geomagnetic field is expected to range from quiet to major storm levels during the period. Residual coronal hole effects are expected on 08 October and could produce active to isolated minor storm levels. A large coronal hole is due to return on 14 – 22 October and is expected to produce major storm levels.