:Product: Weekly Highlights and Forecasts :Issued: 2003 Nov 18 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 10 - 16 November 2003 Activity ranged from low to moderate levels. The summary period began on 10 November with low level activity. Region 498 (S04, L=170, class/area Dao/220 on 11 November) exhibited a brief period of rapid growth on 10 –11 November. During this rapid growth period, Region 498 produced moderate level activity with an M1/Sf flare at 1351 UTC on 11 November. Associated with this M1 flare was a Tenflare, a Type II (481 km/s) radio sweep, and a large CME, which was mostly westward directed and measured approximately 1100 km/s plane of sky speed. Activity returned to low levels on 12 November. As Region 498 rotated beyond the west limb on 13 November, new Region 501 (N03, L=002 class/area Dki/380 on 16 November) rotated onto the east limb as a magnetically complex group with a beta-gamma-delta configuration. Region 501 produced two M1 flares on 13 November, one at 0501 UTC and the other at 0929 UTC. The latter M1 flare was a long duration event with an associated Type II radio sweep (595 km/s). From 14 – 16 November, the region produced low level activity with numerous C-class flares, the largest of which was a C7/Sf at 1039 UTC on 16 November. Solar wind data were available from the NASA Advanced Composition Explorer (ACE) spacecraft during most of the summary period. Solar wind speed was elevated near 550 km/s early on 10 November with an increasing trend. By 11 November, solar wind speed reached peak values near 800 km/s due to a coronal hole high speed stream. The Bz component of the IMF was on average slightly southward from 10 – 16 November with the characteristic north-south oscillation associated with coronal hole high speed streams. Bz reached peak values near –15nT. Other significant activity observed during the summary period included a shock passage measured by the NASA/ACE spacecraft at approximately 0520Z on 15 November. The shock produced a 100 km/s jump in solar wind speed and a four-hour period of southward Bz near –10 nT. There were no greater than 10 MeV proton events at geosynchronous orbit during the summary period. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels everyday during the period, 10 – 16 November. Geomagnetic activity ranged from quiet to major storm levels. The dominant source of activity during the week was a large trans-equatorial coronal hole and associated high speed stream. Active to minor storm levels were observed every day during the week and major storm levels were observed on 11, 13, and 15 November. Major storm levels on 15 November were due to the combined effects of the high speed stream and shock passage. Forecast of Solar and Geomagnetic Activity 19 November - 15 December 2003 Solar activity is expected to range from very low to high levels. Old Regions 484 and 488 have returned as Regions 501 and 507 (N10, L=293) respectively. Old Region 486 (S22, L= 290) which was very active last rotation is due to return to the visible disk on 19 November. Activity is expected to be at low to moderate levels with periods of high level activity during the first half of the period. Activity in the second half of the period is expected to be at very low to moderate levels. Proton producing flares are possible from Region 501 and 507 during the first half of the period. The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 19 – 21 November due to high speed stream effects. Late in the period as this large trans-equatorial coronal hole returns to a geoeffective position the electron flux is expected to reach high levels again (09 – 15 December). The geomagnetic field is expected to range from quiet to major storm levels. Residual high speed stream effects are expected to diminish by 20 November. Transient effects from CMEs observed on 17 –18 November will likely combine with high speed stream effects to produce major storm levels on 19 – 21 November. Additional geomagnetic activity is possible during the first half of the period, in association with major flares and CMEs expected from Regions 501 and 507.