:Product: 20010517RSGA.txt :Issued: 2001 May 17 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 137 Issued at 2200Z on 17 May 2001 IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity was moderate due to a single M-class event, an M1/1f flare from Region 9455 (S16W66) at 17/1652. Regions 9451 (S20W90+), 9454 (N14W22), and 9455 all produced C-class events during the period. Region 9455 produced a C9/1f at the end of the reporting period. Region 9461 (N18E49), returning Region 9433 (responsible for major flares during its previous two rotations), continued to show little activity and is currently a 4-spot D-type group. IB. Solar Activity Forecast: Solar activity is expected to be at low to moderate levels. Regions 9454 and 9455 could produce isolated M-class events during the forecast period. IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field ranged from quiet to unsettled levels. The greater than 2 MeV electron flux at geosynchronous orbit reached high levels during the period. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels with a possibility of isolated active periods at high latitudes on 18 May. The greater than 2 MeV electron flux may reach high levels during the period. III. Event Probabilities 18 May-20 May Class M 40/40/40 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 17 May 147 Predicted 18 May-20 May 150/155/160 90 Day Mean 17 May 167 V. Geomagnetic A Indices Observed Afr/Ap 16 May 007/012 Estimated Afr/Ap 17 May 010/012 Predicted Afr/Ap 18 May-20 May 012/020-010/012-008/010 VI. Geomagnetic Activity Probabilities 18 May-20 May A. Middle Latitudes Active 30/20/20 Minor storm 10/05/05 Major-severe storm 01/01/01 B. High Latitudes Active 35/25/25 Minor storm 15/10/10 Major-severe storm 01/01/01