:Product: 0521RSGA.txt :Issued: 2026 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 Solar Geophysical Activity Report and Forecast SDF Number 141 Issued at 2200Z on 21 May 2026 IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at low levels for the past 24 hours. There are currently 5 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares on days one, two, and three (22 May, 23 May, 24 May). IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 490 km/s at 21/1022Z. Total IMF reached 5 nT at 21/0000Z. The maximum southward component of Bz reached -4 nT at 21/0053Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2841 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (22 May, 23 May) and quiet levels on day three (24 May). III. Event probabilities 22 May-24 May Class M 25/25/25 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 21 May 118 Predicted 22 May-24 May 120/120/125 90 Day Mean 21 May 124 V. Geomagnetic A Indices Observed Afr/Ap 20 May 008/008 Estimated Afr/Ap 21 May 007/008 Predicted Afr/Ap 22 May-24 May 007/008-008/008-006/005 VI. Geomagnetic Activity Probabilities 22 May-24 May A. Middle Latitudes Active 25/20/10 Minor Storm 05/05/05 Major-severe storm 01/01/01 B. High Latitudes Active 20/20/15 Minor Storm 30/30/20 Major-severe storm 30/20/20