:Product: 20011021RSGA.txt :Issued: 2001 Oct 21 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 294 Issued at 2200Z on 21 Oct 2001 IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was at moderate levels. Region 9661 (N14W64) produced an M2/2n flare at 21/1136 UTC with associated discrete frequency radio bursts. Analysis in white light of this region also shows a re-emergence of the delta magnetic configuration. An optically uncorrelated M1 flare was observed at 21/0518 UTC and an associated Type II radio sweep with a shock velocity of 536 km/s. Using SXI imagery it would appear that this flare had occurred in Region 9670 (S18E06). Several C-class flares were produced from Region 9674 (S09E07) during the period. IB. Solar Activity Forecast: Solar activity is expected to be at moderate to high levels. Regions 9661 and 9670 remain capable of producing M-class or isolated major flares. IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field ranged from quiet to major storm levels. A strong shock was observed at ACE at 21/1614 UTC. This was followed by a sudden impulse at 21/1645 UTC (measured as 15 nt on the Boulder magnetometer). The sudden impulse was followed by minor (21/1500-1800 UTC) and major (21/1800-2100 UTC) storm levels. BZ was predominantly negative since the arrival of shock up until the time of issue of this bulletin. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at active to major storm levels. The full halo CME from the X1/2b flare that occurred at 19/1630 UTC from Region 9661 is expected to arrive on the middle of day one of the forecast period. III. Event Probabilities 22 Oct-24 Oct Class M 75/75/60 Class X 15/15/10 Proton 15/15/10 PCAF yellow IV. Penticton 10.7 cm Flux Observed 21 Oct 224 Predicted 22 Oct-24 Oct 225/225/215 90 Day Mean 21 Oct 191 V. Geomagnetic A Indices Observed Afr/Ap 20 Oct 008/010 Estimated Afr/Ap 21 Oct 025/030 Predicted Afr/Ap 22 Oct-24 Oct 030/035-015/020-012/015 VI. Geomagnetic Activity Probabilities 22 Oct-24 Oct A. Middle Latitudes Active 40/40/15 Minor storm 40/15/01 Major-severe storm 15/05/01 B. High Latitudes Active 30/50/50 Minor storm 50/30/10 Major-severe storm 20/05/01