:Product: 0418RSGA.txt :Issued: 2025 Apr 18 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 108 Issued at 2200Z on 18 Apr 2025 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at low levels for the past 24 hours. There are currently 7 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 (19 Apr, 20 Apr, 21 Apr). IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 558 km/s at 18/0705Z. Total IMF reached 12 nT at 18/0028Z. The maximum southward component of Bz reached -11 nT at 18/0157Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 313 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (19 Apr, 20 Apr) and active to major storm levels on day three (21 Apr). III. Event probabilities 19 Apr-21 Apr Class M 40/40/40 Class X 05/05/05 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 18 Apr 156 Predicted 19 Apr-21 Apr 150/150/150 90 Day Mean 18 Apr 175 V. Geomagnetic A Indices Observed Afr/Ap 17 Apr 011/011 Estimated Afr/Ap 18 Apr 012/013 Predicted Afr/Ap 19 Apr-21 Apr 008/010-008/008-021/035 VI. Geomagnetic Activity Probabilities 19 Apr-21 Apr A. Middle Latitudes Active 15/15/35 Minor Storm 05/05/40 Major-severe storm 01/01/20 B. High Latitudes Active 15/15/05 Minor Storm 25/20/20 Major-severe storm 25/20/75