:Product: Weekly Highlights and Forecasts :Issued: 2003 May 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 May 2003 Solar activity was at very low to low levels. Activity was at low levels for the first five days of the period, 05 – 09 May. The largest event during this time was a C5 flare at N17 from a region on the east limb at 2049 UTC on 07 May. The majority of activity during the period came from Region 349 (S15, L=154, class/area/mag. Ekc/1030/Bg on 04 May). This region was the largest spot group on the disk and produced at least 12 C-class flares. Region 348 (S34, L=149, class/area/mag. Fki/560/Bg on 06 May) contributed to activity levels on 06 – 08 May with minor C-class flares. Region 345 (S17, L=167, class/area/mag. Dao/130/Bg on 02 May), 349 and 348 rotated beyond the west limb on 06 May, 07 May, and 08 May respectively. A ten-degree disappearing solar filament was observed on 07 May near S10W18 at 1342 UTC and an eleven-degree filament near S34W14 disappeared at 2145 UTC. A faint narrow CME was associated with the ten-degree DSF. Activity on the 10 – 11 May was at very low levels. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft for most of the summary period. Solar wind velocity started to rise on 05 May with the onset of a large southern coronal hole high speed flow, reaching 650 km/s by the end of the day. Solar wind velocity continued a gradual increase on 06 – 08 May with peak velocities near 750 km/s. On 09 May, solar wind velocity increased again for a six-hour period with peak velocities near 900 km/s then began a gradual decrease. Velocity continued to decrease on 10 May and ended the day at 550 km/s. A second large southern coronal hole high speed flow rotated into a favorable position on 11 May and solar wind began a gradual rise closing the period near 700 km/s. The Bz component of the interplanetary magnetic field was on average slightly southward for most of the period. Transient flow signatures were observed on 09 – 10 May and coronal hole high speed flow signatures were observed for the rest of the period. 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 reached high levels everyday of the period, 05 – 11 May. The geomagnetic field was at quiet to major storm levels. Activity on 05 – 06 May was at quiet to active conditions with one period of isolated minor storming on 06 May. Activity on 07 – 09 May was predominantly at unsettled to minor storm levels with one period of isolated major storming on 07 May. Unsettled to major storm levels were observed on 10 – 11 May due to the six-hour period of high solar wind speed on 10 may and Bz southward fluctuations near –10 nT as mentioned above Forecast of Solar and Geomagnetic Activity 14 May - 09 June 2003 Solar activity is expected to range from low to moderate activity. Activity is expected to be at very low levels early in the period until Regions 345/349 return on 19 May. These regions are expected to present isolated M-class potential until they rotate beyond the west limb around 02 June. No greater than 10 MeV proton events are expected during the forecast period. The greater than 2 MeV electron flux is expected to reach high levels every day of the period. The geomagnetic field is expected to range from quiet to isolated major storm levels. On 14 – 15 May, isolated major storm levels are possible with the return of a large coronal hole high speed flow. A negative polarity coronal hole is due to return to a geo-effective position on 27 – 30 May with major storming possible. On 02 June, a large positive polarity coronal hole is due to return and could produce unsettled to major storming for the remainder of the period.