:Product: Weekly Highlights and Forecasts :Issued: 2003 Apr 08 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 31 March - 06 April 2003 Solar Activity was at low to moderate levels. The period began on 31 March through 01 April with minor C-class activity from Region 318 (S13, L=244, class/area Dai/60 on 30 March). On 02 ? 06 April, Region 324 (S11, L=189, class/area Dac/340 on 04 April) was the source of most of the activity. Region 324 produced a C3/Sf and a C6/1f flare on 02 and 03 April respectively. The largest event of the period was an M1/1f from Region 324 on 04 April at 2019 UTC. A partial halo CME was associated with this event as seen in LASCO imagery. On 05 and 06 April, Region 324 produced a C6 and C5 flare respectively. Region 324 was in a growth phase early in the period and developed a beta-gamma-delta configuration on 04 April. By the end of the period, this region was in decay. Other regions of note during the period were Region 321 (N05, L=211, class/area Eac/320 on 27 March), and Region 325 (N10, L=165, class/area Ehi/360 on 02 April). Region 321 was in gradual decay for most of the period but produced four minor C-class flares on 04 April. Region 325 was one of the largest regions on the disk but has been relatively stable during the period. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. The period began with residual effects from a high speed coronal hole stream. Solar wind velocity was over 600 km/s at the beginning of the period and decreased to around 525 km/s on March 31 through 01 April. On 02 April, velocity further decreased to 450 km/s and was relatively stable until 05 April. The end of the high speed stream was marked by a rapid decline in solar wind velocity to below 400 km/s on 06 April. Bz exhibited oscillations between +/- 10 nT until 06 April. 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 geo-synchronous orbit was at high levels for the entire summary period, 31 March ? 06 April. The geomagnetic field ranged from quiet to major storm levels. The period began with unsettled to major storm levels on 31 March through early on 01 April due to coronal hole high speed stream effects. Quiet to active conditions were observed on 01 ? 03 April. Multiple periods of prolonged southward Bz on 04 ? 05 April, resulted in unsettled to minor storm levels. Quiet to unsettled conditions were observed on 06 April as effects of the high speed stream subsided. Forecast of Solar and Geomagnetic Activity 09 April - 05 May 2003 Solar activity is expected to range from very low to low levels. The later half of the period will see the return of Regions 321, 323, 324, and 325. Combined, these regions represent a slight chance of M-class activity. No greater than 10 MeV proton events are expected during the forecast period. The greater than 2 MeV electron flux may reach high levels on 13 ? 17 April and again on 27 April ? 03 May due to returning coronal holes. The geomagnetic field is expected to range from unsettled to major storm conditions during the period. A coronal hole is due to return to a geo-effective position on 11 ?14 April with unsettled to minor storm conditions possible. Unsettled to isolated major storm levels are possible with multiple coronal hole high speed streams due on 23 April ? 02 May. .