:Product: 0521RSGA.txt :Issued: 2012 May 21 2200 UTC # Prepared jointly by the U.S. Dept. of Commerce, NOAA, # Space Weather Prediction Center and the U.S. Air Force. # Joint USAF/NOAA Report of Solar and Geophysical Activity SDF Number 142 Issued at 2200Z on 21 May 2012 IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity was very low. No Earth-directed CMEs were observed during the period. IB. Solar Activity Forecast: Solar activity is expected to be at very low to low levels with a slight chance for an M-class flare for the forecast period (22 - 24 May). IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field was at quiet to active levels. A weak interplanetary shock was observed at the ACE spacecraft at 21/1844Z. An associated sudden impulse of 34 nT was observed at the Boulder magnetometer at 21/1937Z. The geomagnetic field responded with an active period between 21/1800 - 2100Z. This activity was likely attributable to the arrival of the 18 May CME. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels with a chance for active periods on days 1-2 (22 - 23 May) as recurrent coronal hole high speed streams (CH HSS) move into a geoeffective position. Quiet to unsettled conditions are expected on day 3 (24 May) as effects of the CH HSS wane. III. Event Probabilities 22 May-24 May Class M 10/10/10 Class X 01/01/01 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 21 May 125 Predicted 22 May-24 May 125/125/120 90 Day Mean 21 May 116 V. Geomagnetic A Indices Observed Afr/Ap 20 May 012/011 Estimated Afr/Ap 21 May 005/007 Predicted Afr/Ap 22 May-24 May 010/010-007/010-007/008 VI. Geomagnetic Activity Probabilities 22 May-24 May A. Middle Latitudes Active 20/20/10 Minor storm 10/10/01 Major-severe storm 01/01/01 B. High Latitudes Active 25/25/15 Minor storm 15/15/05 Major-severe storm 01/01/01