:Product: 0531RSGA.txt :Issued: 2025 May 31 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 151 Issued at 2200Z on 31 May 2025 IA. Analysis of Solar Active Regions and Activity from 30/2100Z to 31/2100Z: Solar activity has been at high levels for the past 24 hours. There are currently 5 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is likely to be moderate with a chance for X-class flares on days one, two, and three (01 Jun, 02 Jun, 03 Jun). IIA. Geophysical Activity Summary 30/2100Z to 31/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 822 km/s at 31/0518Z. Total IMF reached 7 nT at 31/0045Z. The maximum southward component of Bz reached -6 nT at 30/2248Z. Protons greater than 10 MeV at geosynchronous orbit reached a peak level of 25 pfu at 31/2045Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 9162 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at active to severe storm levels on day one (01 Jun), minor storm to severe storm levels on day two (02 Jun) and active to major storm levels on day three (03 Jun). Protons are expected to cross threshold on days one, two, and three (01 Jun, 02 Jun, 03 Jun). III. Event probabilities 01 Jun-03 Jun Class M 65/65/65 Class X 25/25/25 Proton 75/75/75 PCAF yellow IV. Penticton 10.7 cm Flux Observed 31 May 164 Predicted 01 Jun-03 Jun 165/160/150 90 Day Mean 31 May 154 V. Geomagnetic A Indices Observed Afr/Ap 30 May 018/016 Estimated Afr/Ap 31 May 014/018 Predicted Afr/Ap 01 Jun-03 Jun 052/096-055/100-031/044 VI. Geomagnetic Activity Probabilities 01 Jun-03 Jun A. Middle Latitudes Active 05/15/30 Minor Storm 40/35/35 Major-severe storm 55/55/25 B. High Latitudes Active 01/01/05 Minor Storm 05/05/15 Major-severe storm 95/95/80