:Product: 20010407RSGA.txt :Issued: 2001 Apr 07 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 097 Issued at 2200Z on 07 Apr 2001 IA. Analysis of Solar Active Regions and Activity from 06/2100Z to 07/2100Z: Solar activity decreased to low levels. A single C-class X-ray flare occurred. Region 9415 (S21E21) remained the dominant region on the disk with a minor increase in area and spots. It remained magnetically complex with a strong delta configuration within its leader spots. Minor growth was reported in Region 9417 (S08E01), but the region remained a simply-structured bipole. New Regions 9421 (S15W42) and 9422 (S13E78) were numbered. IB. Solar Activity Forecast: Solar activity is expected to be at moderate to high levels. Region 9415 may produce a major flare during the period. IIA. Geophysical Activity Summary 06/2100Z to 07/2100Z: Geomagnetic field activity ranged from unsettled to minor storm levels. A shock passed the ACE spacecraft at about 07/1700 UTC, presumably from the long-duration M5 X-ray flare and halo-CME event observed on 05 April. The greater than 10 MeV proton flux gradually declined, but remained enhanced. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at unsettled to minor storm levels during the first two days due to an expected CME passage associated with the X5 flare of 06 April. The CME is expected to reach Earth around midday tomorrow. Quiet to active levels are expected on the final day. There will be a chance for a proton flare from Region 9415 during the period. III. Event Probabilities 08 Apr-10 Apr Class M 80/80/80 Class X 25/25/25 Proton 60/25/25 PCAF yellow IV. Penticton 10.7 cm Flux Observed 07 Apr 180 Predicted 08 Apr-10 Apr 175/175/170 90 Day Mean 07 Apr 167 V. Geomagnetic A Indices Observed Afr/Ap 06 Apr 011/012 Estimated Afr/Ap 07 Apr 025/025 Predicted Afr/Ap 08 Apr-10 Apr 025/030-025/030-015/020 VI. Geomagnetic Activity Probabilities 08 Apr-10 Apr A. Middle Latitudes Active 40/40/30 Minor storm 30/30/15 Major-severe storm 10/10/05 B. High Latitudes Active 40/40/30 Minor storm 35/35/20 Major-severe storm 15/15/10