:Product: Weekly Highlights and Forecasts :Issued: 2003 Nov 25 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 17 - 23 November 2003 Solar activity ranged from low to high levels. The period began with moderate level activity on 17 –19 November. Region 501 (N03, L=002, class/area Dhc/410 on 18 November) produced the first of nine M-class flares at 0905 UTC on 17 November, an M4.2/1n flare. This flare was accompanied by a Type II (445 km/s) radio sweep and a CME with an estimated plane of sky speed of 1085 km/s. On 18 November, a pair of M3/2n flares was observed from Region 501 with peak flux times at 0752 and 0831 UTC. Strong radio bursts, a Tenflare, a Type IV, and two separate Type II radio sweeps were associated with the M3s. Simultaneous with the first flare, a fourteen-degree filament to the south and west of Region 501 erupted at 0716 UTC. LASCO imagery depicted a full halo CME as a combined result of these events. An impulsive M1 flare was observed from Region 501 on 19 November. High level activity occurred on 20 November due to an M9.6/2b flare at 0747 UTC and an M5.8 flare at 2353 UTC. The M9 was associated with a Type IV radio sweep, a 9700 sfu Tenflare, and a faint full halo CME. New regions 507 (N10, L=295, class/area Eki/890 on 19 November) and 508 (S20, L=286, class/area Dko/680 on 20 November) rotated onto the east limb on 18 and 19 November respectively. Regions 507 and 508 are thought to be old Region 488 and 486, respectively. Both of these regions appear to have maintained at least some of their complex magnetic structure during their transit on the backside of the Sun; although old Region 486 has decayed considerably. Region 507 has shown some mix polarities and a beta-gamma-delta configuration while Region 508 had a beta-gamma configuration for most of the period. An M4.5 event was observed at 1011 UTC on 18 November and appears to have originated from Region 508 just prior to it rotating onto the disk. Activity on 21 – 23 November decreased to low levels as Regions 501, 507 and 508 exhibited some level of decay and simplification in magnetic complexity. Region 501 simplified to a beta-gamma magnetic configuration on 22 November. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft during most of the summary period. A coronal hole high speed stream was in progress at the beginning of the period with wind speed near 825 km/s. On 19 November, wind speed dropped off to around 450 km/s as the coronal hole rotated beyond a geoeffective position. A shock from the CME on 18 November was observed passing the L1 point at 0740 UTC on 20 November. The MTOF/PM instrument on the SOHO spacecraft recorded a 350 km/s increase in solar wind speed to over 800 km/s. The NASA/ACE satellite data were not available during the shock however, post shock data indicated total IMF measured close to 60 nT and the Bz component decreased to around –60 nT. Towards the end of the period, 22 –23 November, a second coronal hole high speed stream rotated into a geoeffective position producing elevated solar wind speed at around 575 km/s. The M5 flare late on 20 November was the likely source of a greater than 10 MeV proton event starting at 2355 UTC on 21 November. The small event reached a peak value of 13.9 pfu at 0230 UTC on 22 November, and ended at 0715 UTC on 22 November. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 17 – 20 November and again on 23 November. Geomagnetic activity ranged from quiet to severe storm levels. The period began with unsettled to minor storm levels on 17 November and unsettled to active levels on 18 – 19 November. This activity was due to the coronal hole high speed stream in progress during the early part of the period. On 20 November, a CME shock from the activity on 18 November produce major to severe geomagnetic storming on 20 November and early on 21 November. This geomagnetic storm began following a 56 nT sudden impulse measured on the Boulder magnetometer at 0804 UTC on 20 November. GOES satellites observed magnetopause crossings on 20 November, GOES 12 at 1301 UTC and GOES 10 at 1628 UTC. Activity on 22 and 23 November was at active to minor storm levels due to another coronal hole high speed stream. Forecast of Solar and Geomagnetic Activity 26 November - 22 December 2003 Solar activity is expected to range from very low to moderate levels with a small chance of high level activity. Activity is expected to be at low to moderate levels with high level activity possible during the first week of the period. Activity after 02 December when Regions 507 and 508 rotate beyond the west limb is expected to be at very low to moderate levels. Proton producing flares are possible from Region 507, and 508 during the first week of the period. After 02 December, no greater than 10 MeV proton events are expected. 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.