:Product: 20010918RSGA.txt :Issued: 2001 Sep 18 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 261 Issued at 2200Z on 18 Sep 2001 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity remained at high levels due to the number of M-class flares. Six M1-level flares were observed over the past 24 hours, occurring in Regions 9608 (S30W84), 9616 (S13W11), 9620 (N12E44), and new Region 9628 (S17E79). Region 9608 has rotated out of view beyond the west limb. The largest sunspot groups currently on the disk are 9616 and 9628. New Regions 9625 (S30W12), 9626 (N25E47), and 9627 (N05E73) were also numbered. IB. Solar Activity Forecast: Solar activity is expected to be moderate to high. Additional M-class flares are possible in Regions 9616, 9620, and 9628. Another major flare in Region 9608 from beyond the west limb is not out of the question. IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field ranged from quiet to active. Solar wind information from the NASA ACE spacecraft exhibited increased variability including higher IMF field intensity and southward Bz. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled with occasional active periods. Increased activity is possible from a number of CME events and a possible high-speed coronal hole stream. III. Event Probabilities 19 Sep-21 Sep Class M 80/80/80 Class X 10/05/05 Proton 10/01/01 PCAF yellow IV. Penticton 10.7 cm Flux Observed 18 Sep 204 Predicted 19 Sep-21 Sep 205/200/195 90 Day Mean 18 Sep 165 V. Geomagnetic A Indices Observed Afr/Ap 17 Sep 006/010 Estimated Afr/Ap 18 Sep 008/010 Predicted Afr/Ap 19 Sep-21 Sep 015/020-012/015-010/010 VI. Geomagnetic Activity Probabilities 19 Sep-21 Sep A. Middle Latitudes Active 20/15/10 Minor storm 10/10/05 Major-severe storm 01/01/01 B. High Latitudes Active 25/20/15 Minor storm 15/15/10 Major-severe storm 05/01/01