:Product: 0417RSGA.txt :Issued: 2026 Apr 17 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 107 Issued at 2200Z on 17 Apr 2026 IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity has been at low levels for the past 24 hours. There are currently 3 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 (18 Apr, 19 Apr, 20 Apr). IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 365 km/s at 17/0316Z. Total IMF reached 11 nT at 17/1729Z. The maximum southward component of Bz reached -3 nT at 17/1744Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2441 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at unsettled to major storm levels on day one (18 Apr), unsettled to minor storm levels on day two (19 Apr) and quiet to active levels on day three (20 Apr). III. Event probabilities 18 Apr-20 Apr Class M 25/25/25 Class X 05/05/05 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 17 Apr 107 Predicted 18 Apr-20 Apr 105/105/105 90 Day Mean 17 Apr 133 V. Geomagnetic A Indices Observed Afr/Ap 16 Apr 003/003 Estimated Afr/Ap 17 Apr 015/020 Predicted Afr/Ap 18 Apr-20 Apr 025/040-020/025-014/018 VI. Geomagnetic Activity Probabilities 18 Apr-20 Apr A. Middle Latitudes Active 30/35/35 Minor Storm 40/35/10 Major-severe storm 25/10/01 B. High Latitudes Active 05/05/15 Minor Storm 15/20/30 Major-severe storm 85/70/45