:Product: 20040528RSGA.txt :Issued: 2004 May 28 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 149 Issued at 2200Z on 28 May 2004 IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity has been low. Region 618 (S10W44) produced several impulsive C-class flares, the largest a C4.1 at 28/1011 UTC. Region 618 is stable in size, but has decreased in magnetic complexity to a beta-gamma configuration. No new regions were numbered today. IB. Solar Activity Forecast: Solar activity is expected to be low. Region 618 may produce C- and isolated M-class flares. IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field has been quiet to unsettled. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled for the next three days. Isolated active conditions are possible late on day three (May 31) as a coronal hole high speed solar wind stream begins to move into geoeffective position. NOTE: The ACE spacecraft orbit will bring ACE nearly in line with the Sun from about 30 May to 2 June 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 29 May-31 May Class M 40/40/40 Class X 05/05/05 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 28 May 102 Predicted 29 May-31 May 100/105/105 90 Day Mean 28 May 105 V. Geomagnetic A Indices Observed Afr/Ap 27 May 005/006 Estimated Afr/Ap 28 May 008/012 Predicted Afr/Ap 29 May-31 May 005/012-008/012-010/012 VI. Geomagnetic Activity Probabilities 29 May-31 May A. Middle Latitudes Active 10/15/20 Minor storm 05/05/15 Major-severe storm 01/01/05 B. High Latitudes Active 25/30/30 Minor storm 15/20/25 Major-severe storm 05/05/10