:Product: 20010523RSGA.txt :Issued: 2001 May 23 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 143 Issued at 2200Z on 23 May 2001 IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity was low. Isolated low C-class flares were observed. Region 9463 (N07E04) has doubled in size since yesterday exceeding 750 millionths of white light areal coverage by end of period. Despite its size, this region exhibits a fairly simple beta configuration with no obvious complexity. Region 9468 (N05E39) also doubled in size exceeding 200 millionths with moderate complexity. Two new regions were numbered today - 9471 (S13W02), and 9472 (N12E61). IB. Solar Activity Forecast: Solar activity is expected to be low. A very isolated chance exists for an M-class flare from Regions 9463 or 9468. IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic field was quiet to active. The onset of a high speed coronal hole stream occurred at approximately 23/0200Z. Solar wind speed has gradually increased from 300 km/s to 450 km/s; consequently, unsettled to active conditions were predominant during the latter half of the period. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be unsettled to active through day one due to high speed coronal hole flow. Quiet to unsettled conditions should return on days two and three. III. Event Probabilities 24 May-26 May Class M 40/40/40 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 23 May 159 Predicted 24 May-26 May 165/170/170 90 Day Mean 23 May 168 V. Geomagnetic A Indices Observed Afr/Ap 22 May 008/009 Estimated Afr/Ap 23 May 015/012 Predicted Afr/Ap 24 May-26 May 015/018-010/012-008/010 VI. Geomagnetic Activity Probabilities 24 May-26 May A. Middle Latitudes Active 40/25/20 Minor storm 15/10/05 Major-severe storm 05/01/01 B. High Latitudes Active 50/40/30 Minor storm 25/15/10 Major-severe storm 05/05/01