:Product: 0528RSGA.txt :Issued: 2025 May 28 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 148 Issued at 2200Z on 28 May 2025 IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity has been at low levels for the past 24 hours. There are currently 8 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares and a slight chance for an X-class flare on days one, two, and three (29 May, 30 May, 31 May). IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 648 km/s at 28/0246Z. Total IMF reached 18 nT at 28/2040Z. The maximum southward component of Bz reached -9 nT at 27/2102Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 416 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on days one and two (29 May, 30 May) and quiet to active levels on day three (31 May). Protons have a slight chance of crossing threshold on days one, two, and three (29 May, 30 May, 31 May). III. Event probabilities 29 May-31 May Class M 50/50/50 Class X 10/10/10 Proton 10/10/10 PCAF green IV. Penticton 10.7 cm Flux Observed 28 May 144 Predicted 29 May-31 May 140/138/135 90 Day Mean 28 May 154 V. Geomagnetic A Indices Observed Afr/Ap 27 May 012/ 015 Estimated Afr/Ap 28 May 019/021 Predicted Afr/Ap 29 May-31 May 017/020-014/018-008/012 VI. Geomagnetic Activity Probabilities 29 May-31 May A. Middle Latitudes Active 40/40/30 Minor Storm 25/25/10 Major-severe storm 05/05/01 B. High Latitudes Active 10/10/15 Minor Storm 25/25/30 Major-severe storm 60/60/40