:Product: 20011025RSGA.txt :Issued: 2001 Oct 25 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 298 Issued at 2200Z on 25 Oct 2001 IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: Solar Activity was at high levels. Region 9672 (S18W27) produced a X1/3B flare at 25/1502 UTC with associated Type II (est. velocity 900 km/s) and Type IV events observed. SOHO/LASCO imagery indicate a full halo CME with a plane of sky speed of 884 km/s. Region 9672 also produced three minor C-class flares. Region 9678 (N08E20) has grown significantly in the last 24 hours. This region has increased in area coverage, spot count, and magnetic complexity to 300 millionths, 35 spots, and Beta-Gamma-Delta configuration, respectively. Other activity on the disc was six minor C-class flares most of which came from Region 9672 and 9678. New Region 9681 (S25E05) and Region 9682 (N09E70) were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be at low to moderate levels with a chance for an isolated high condition. Region 9672 and Region 9678 both have the potential of producing a major flare. Both of these regions are active and magnetically complex. New Region 9682 is just rotating on to the disc but already appears to be a large and potentially complex region. IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: Geomagnetic activity was at quiet to unsettled levels. Shock arrival from the two CMEs (M6/2N on 22/1502 UTC and X1/2B on 22/1759 UTC) occurred at 25/0850 UTC with a sudden impulse of 22 nT recorded on the Boulder magnetometer. A north directed Bz component to the interplanetary magnetic field resulted in only unsettled conditions. IIB. Geophysical Activity Forecast: Geomagnetic activity is expected to be at quiet to major storm levels. Quiet to active levels are expected on day one of the period. Analysis of the X1/3B full halo CME on 25/1502 UTC indicates that shock arrival is expected late on day two or early on day three of the period. Shock arrival is expected to produce unsettled to minor storm levels for day two and three of the period. Isolated major storm levels are possible particularly at higher latitudes. III. Event Probabilities 26 Oct-28 Oct Class M 75/75/75 Class X 35/25/25 Proton 25/15/15 PCAF yellow IV. Penticton 10.7 cm Flux Observed 25 Oct 239 Predicted 26 Oct-28 Oct 230/225/220 90 Day Mean 25 Oct 196 V. Geomagnetic A Indices Observed Afr/Ap 24 Oct 004/003 Estimated Afr/Ap 25 Oct 006/008 Predicted Afr/Ap 26 Oct-28 Oct 008/010-018/020-025/030 VI. Geomagnetic Activity Probabilities 26 Oct-28 Oct A. Middle Latitudes Active 25/50/50 Minor storm 05/30/30 Major-severe storm 01/15/15 B. High Latitudes Active 30/45/45 Minor storm 15/35/35 Major-severe storm 01/20/20