:Product: 20040525RSGA.txt :Issued: 2004 May 25 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 146 Issued at 2200Z on 25 May 2004 IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: Solar activity was at low levels. Region 615 (N17W53) produced the largest flare of the period, a C1 x-ray event that occurred at 24/2239Z. Region 618 (S10W00) was limited to B-class flare production this period while two delta structures remain evident across the magnetic region center in this beta-gamma-delta complex. Little change was noted in sunspot area today. A 20 degree filament that was seen near the north-center of the disk became active just before 24/1800Z, and had fully erupted by 24/1930Z. This disappearing filament resulted in a northward directed CME as seen on LASCO imagery and appears to have little geoeffective potential. No new regions were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be at low to moderate levels. Region 618 remains capable of producing isolated M-class flare activity. IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic field was at quiet to unsettled levels. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels throughout the period. NOTE: The ACE spacecraft orbit will bring ACE nearly in line with the Sun from about May 30 to June 2, 2004. During that time solar radio noise is expected to interfere with spacecraft telemetry resulting in the loss of solar wind plasma, magnetic field, and particle data. III. Event Probabilities 26 May-28 May Class M 50/50/50 Class X 10/10/10 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 25 May 102 Predicted 26 May-28 May 100/100/105 90 Day Mean 25 May 105 V. Geomagnetic A Indices Observed Afr/Ap 24 May 008/011 Estimated Afr/Ap 25 May 007/010 Predicted Afr/Ap 26 May-28 May 007/010-010/010-010/010 VI. Geomagnetic Activity Probabilities 26 May-28 May A. Middle Latitudes Active 15/20/20 Minor storm 05/10/10 Major-severe storm 05/05/05 B. High Latitudes Active 20/20/20 Minor storm 10/10/10 Major-severe storm 05/05/05