:Product: 0517RSGA.txt :Issued: 2026 May 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 137 Issued at 2200Z on 17 May 2026 IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity has been at moderate 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 (18 May, 19 May, 20 May). IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 734 km/s at 16/2108Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 6117 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on days one and two (18 May, 19 May) and quiet levels on day three (20 May). III. Event probabilities 18 May-20 May Class M 40/45/45 Class X 05/05/05 Proton 05/05/01 PCAF green IV. Penticton 10.7 cm Flux Observed 17 May 104 Predicted 18 May-20 May 105/110/115 90 Day Mean 17 May 124 V. Geomagnetic A Indices Observed Afr/Ap 16 May 019/034 Estimated Afr/Ap 17 May 011/013 Predicted Afr/Ap 18 May-20 May 015/021-018/021-007/008 VI. Geomagnetic Activity Probabilities 18 May-20 May A. Middle Latitudes Active 40/35/20 Minor Storm 30/30/05 Major-severe storm 05/05/01 B. High Latitudes Active 05/10/20 Minor Storm 25/25/30 Major-severe storm 60/60/25