:Product: Weekly Highlights and Forecasts :Issued: 2003 Dec 02 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 24 - 30 November 2003 Solar activity was at low levels during the summary period. Region 508 (S20, L=286, class/area Dko/680 on 20 November) was the most active region during the period. This region contained moderate magnetic complexity with a beta-gamma configuration and produced twenty C-class flares during the period. It also produced the largest flare of the period on 27 November, a C9/Sf at 0820 UTC. Moderately complex Region 501 (N18, L=002 class/area Dhc/410 on 18 November) was in gradual decay as it approached the west limb, and made a quiet exit off the visible disk on 26 November. Region 507 (N10, L=295, class/area Eki/890 on 19 November), though in decay phase, exhibited considerable size and complexity throughout the period. A weak delta configuration persisted; however, activity was limited to very isolated low C-class flares. Late in the period, Region 517 (S07, L=145, class/area Cao/160 on 30 November) rotated onto the visible disk and produced occasional C-class activity. This region continues in a slow growth phase. There have been a number of other smaller regions on the visible disk during the summary period, all of which are unremarkable and simple in magnetic structure. At the time of this report issue, long duration X-ray activity and a strong eruption was observed to occur from near Region 508 on the southwest limb. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft during most of the summary period. The period began with elevated solar wind speeds due to a coronal hole high speed stream. Early on 25 November, wind speeds reached 650 km/s with the Bz component of the IMF remaining predominantly northward. From 25 – 29 November, solar wind speed was in gradual decline to around 375 km/s. Another coronal hole rotated into a geoeffective position on 30 November with wind speed increasing to 500 km/s and Bz turning southward to around –5 nT. The greater than 10 MeV proton flux was enhanced early in the period following a small proton event on 21 – 22 November, but returned to background levels by 26 November. At the time of this report issue, a greater than 10 MeV proton event is in progress most likely due to the long duration X-ray activity on 02 December. The event began at 1505 UTC on 02 December and current flux levels are at 85 pfu. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels every day during the summary period, 24 – 30 November. Geomagnetic activity was at quiet to unsettled levels during the summary period. One period of isolated active conditions was observed on 24 November. Brief periods of minor and major storm levels were observed at higher latitudes on 24 – 25 November due to effects from a coronal hole high speed stream. The coronal hole on 30 November produced no significant geomagnetic response. Forecast of Solar and Geomagnetic Activity 03 - 29 December 2003 Solar activity is expected to range from very low to low levels with a chance of moderate level activity. Activity is expected to be at low levels during the first half of the period. Active longitudes are due to return to the visible disk by mid December and may produce moderate levels. The greater than 10 MeV proton event currently in progress has reached flux levels of 85 pfu at this time and is expected to end by 03 December. There is a slight chance of a proton event after 15 December when active longitudes return to the visible disk. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 09 – 15 December due to a large trans-equatorial coronal hole. The geomagnetic field is expected to range from quiet to major storm levels. A large trans-equatorial coronal hole is due to return to a geoeffective position on 06 – 13 December and is expected to produce minor to major storming.