:Product: 20011212RSGA.txt :Issued: 2001 Dec 12 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 346 Issued at 2200Z on 12 Dec 2001 IA. Analysis of Solar Active Regions and Activity from 11/2100Z to 12/2100Z: Solar activity decreased to moderate levels. Region 9733 (N14E18) produced an M3/1n flare at 12/1911 UTC associated with a 420 sfu Tenflare. This large, complex spot group remained in a growth phase with a delta magnetic configuration observed within its northernmost trailer spots. Region 9727 (S21W52) produced occasional subflares, the largest of which was a C9 at 12/2024 UTC. This region also grew during the period and remained large and complex with delta magnetic configurations in its interior and trailer spots. Region 9736 (S09W55) showed minor growth during the period and produced isolated C-class subflares. New Region 9738 (S21E67) was numbered. IB. Solar Activity Forecast: Solar activity is expected to be at moderate to high levels with isolated, low-level M-class flares likely. There will also be a chance for a major flare from Regions 9727 or 9733. IIA. Geophysical Activity Summary 11/2100Z to 12/2100Z: Geomagnetic field activity ranged from quiet to minor storm levels. Unsettled to minor storm levels occurred during 12/0900 - 1200 UTC. ACE data suggest a solar sector boundary crossing (positive- to negative-polarity) as the cause for this brief period of increased activity. Mostly quiet levels occurred during the remainder of the period. IIB. Geophysical Activity Forecast: Geomagnetic field activity is expected to be at quiet to unsettled levels during most of the period. However, brief active periods will be possible during 14 - 15 December due to coronal hole effects. There will be a chance for a proton flare from Regions 9727 or 9733. III. Event Probabilities 13 Dec-15 Dec Class M 80/80/80 Class X 20/20/20 Proton 20/20/20 PCAF yellow IV. Penticton 10.7 cm Flux Observed 12 Dec 237 Predicted 13 Dec-15 Dec 220/220/210 90 Day Mean 12 Dec 219 V. Geomagnetic A Indices Observed Afr/Ap 11 Dec 003/004 Estimated Afr/Ap 12 Dec 012/012 Predicted Afr/Ap 13 Dec-15 Dec 012/012-012/015-012/015 VI. Geomagnetic Activity Probabilities 13 Dec-15 Dec A. Middle Latitudes Active 20/20/20 Minor storm 10/10/10 Major-severe storm 01/01/01 B. High Latitudes Active 25/25/25 Minor storm 15/15/15 Major-severe storm 05/05/01