:Product: Weekly Highlights and Forecasts :Issued: 2003 Aug 05 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 28 July - 03 August 2003 Solar activity was at low to moderate levels. A moderately complex beta-gamma configuration was evident in Region 421 (S08, L=355 class/area Eao/310 on 29 July) on the 28th and occasional minor C-class flares were noted. Activity increased to moderate levels on 29 July when Region 421 produced an M1/1f at 0139 UTC. Region 422 (N14, L=103 class/area Dao/200 on 29 July) also emerged quite quickly on the 28th and was responsible for low C-class flares on the 28th and 29th. Moderate levels were again observed on 30 July as Region 422 produced an M2/1b flare at 0410 UTC, with associated centimetric bursts including a 190 sfu Tenflare. Activity decreased to low levels on 31 July and 01 August. Both Region 421 and 422 entered a decay phase on the 30th that continued through the end of the period. On 01 August, new Region 424 (S18, L=291, class/area Dki/580 on 03 August) rotated onto the visible disk. Region 424 produced at least six C-class flares on 01 August with the largest one a C5 at 0126 UTC. Region 424 continued a rapid growth phase on 02 – 03 August and produced moderate level activity on 02 August with an M1/1f at 2354 UTC. LASCO imagery indicates a full halo CME associated with the M1 event, however further analysis suggests that the halo may be from a backside event. The period ended on 03 August with minor C-class activity from Region 424. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. A large coronal hole high speed stream began on 28 July and dominated the period. Solar wind speeds increased late on the 28th and were elevated near 750 – 900 km/s for most of the period. Wind speed began a steady decline late on 01 August and reached 550 km/s at the close of the period. The Bz component of the interplanetary magnetic field oscillated between +/- 10 nT early in the period but was between +/- 6 nT for most of the period. There were no greater than 10 MeV proton events at geosynchronous orbit during the period. The greater than 2 MeV electron flux at geo-synchronous orbit reached high levels on 29 July – 03 August. The geomagnetic field ranged from quiet to minor storm levels. A large coronal hole high speed stream was responsible for all of the minor storm activity during the period. Activity was at unsettled to minor storm levels on 28 July – 01 August with a 15-hour period of continuous minor storm condition on 01 August. High speed stream effects diminished on 02 – 03 August with unsettled to active conditions. Forecast of Solar and Geomagnetic Activity 06 August - 01 September 2003 Solar activity is expected to range from low to moderate levels during the period. Region 424 has the potential for isolated M-class activity during the first half of the period. An area of active longitudes is due to return to the visible disk on 08 August and is expected to have C-class and isolated M-class potential. Activity during the second half of the period is expected to be at low levels. No greater than 10 MeV proton events at geosynchronous orbit are expected. The greater than 2 MeV electron flux is expected to reach high levels on 09 - 11 August, on 13 –15 August and again on 25 August – 01 September. The geomagnetic field is expected to range from quiet to major storm levels during the period. Coronal hole effects are expected on 07 - 09 August and 11 – 13 August with isolated major storm levels possible. The large coronal hole high speed stream is due to return late in the period and is expected to produce minor storm levels on 22 – 29 August.