:Product: 20011215RSGA.txt :Issued: 2001 Dec 15 2200 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Environment Center and the U.S. Air Force. # Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 349 Issued at 2200Z on 15 Dec 2001 IA. Analysis of Solar Active Regions and Activity from 14/2100Z to 15/2100Z: Solar activity decreased to low levels. There were two large, magnetically complex sunspot groups on the visible disk: Region 9727 (S22W88) and Region 9733 (N14W23). Region 9727 produced isolated subflares while crossing the west limb. It retained at least a moderate degree of magnetic complexity as it rotated out of view with mixed polarities in its trailer spots. Region 9733 remained the most active region on the disk as it produced occasional subflares, some of which reached C-class. This region has showed a gradual decrease in area since 13 December. However, opposite-polarity magnetic flux has gradually emerged within its northernmost spots during the last two days where a possible delta magnetic configuration may reside. The remaining active regions showed minor changes during the period. New Region 9742 (N09E73) rotated into view during the period. IB. Solar Activity Forecast: Solar activity is expected to be at moderate to high levels. Isolated low-level M-class flares are expected. There will also be a chance for a major flare from Region 9733. Region 9727 could also produce a major flare during the first day of the period as it completes its west limb passage. IIA. Geophysical Activity Summary 14/2100Z to 15/2100Z: Geomagnetic field activity was at quiet to unsettled levels. IIB. Geophysical Activity Forecast: Unsettled to minor storm conditions may occur on 16 - 17 December due to a possible CME passage (associated with the X6/3b flare of 13 December). Activity is expected to decrease to quiet to unsettled levels during the latter half of the forecast period. There will be a chance for a proton flare from Region 9733. III. Event Probabilities 16 Dec-18 Dec Class M 80/75/75 Class X 20/15/15 Proton 20/15/15 PCAF yellow IV. Penticton 10.7 cm Flux Observed 15 Dec 218 Predicted 16 Dec-18 Dec 205/195/190 90 Day Mean 15 Dec 218 V. Geomagnetic A Indices Observed Afr/Ap 14 Dec 004/004 Estimated Afr/Ap 15 Dec 013/012 Predicted Afr/Ap 16 Dec-18 Dec 015/020-015/015-010/010 VI. Geomagnetic Activity Probabilities 16 Dec-18 Dec A. Middle Latitudes Active 35/30/25 Minor storm 15/10/05 Major-severe storm 05/01/01 B. High Latitudes Active 40/35/30 Minor storm 20/15/05 Major-severe storm 10/05/01