:Product: 20011220RSGA.txt :Issued: 2001 Dec 20 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 354 Issued at 2200Z on 20 Dec 2001 IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: Solar activity was low. Region 9742 (N10E13) produced several C-class events including a C8 flare at 20/0438Z. This region exhibited impressive flux emergence and spot growth this period, almost doubling in size and spot count. Most growth was concentrated in the trailer portions of the region, but mixed polarities were obvious throughout the spot group. Regions 9741 (N05W21) and 9747 (N12E58) produced occasional minor C-class flares. Moderately complex Regions 9733 (N12W88) and 9739 (S14W90) are rotating quietly around the west limb. A large prominence eruption and associated CME occurred on the SE limb between 19/2344 - 20/0028Z. New Regions 9748 (S11E36), and 9749 (S08E72) were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be at moderate levels. Region 9742 holds good potential for M-class activity and is developing potential for a major flare. IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field was quiet. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled. Periods of unsettled conditions are likely on days two and three as a large southern coronal hole moves into a geoeffectively favorable position. III. Event Probabilities 21 Dec-23 Dec Class M 60/60/60 Class X 10/10/10 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 20 Dec 221 Predicted 21 Dec-23 Dec 215/215/215 90 Day Mean 20 Dec 218 V. Geomagnetic A Indices Observed Afr/Ap 19 Dec 005/009 Estimated Afr/Ap 20 Dec 005/006 Predicted Afr/Ap 21 Dec-23 Dec 008/008-008/008-010/008 VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec A. Middle Latitudes Active 20/20/25 Minor storm 05/05/05 Major-severe storm 01/01/01 B. High Latitudes Active 20/25/25 Minor storm 05/05/05 Major-severe storm 01/01/01