:Product: 0518RSGA.txt :Issued: 2026 May 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 138 Issued at 2200Z on 18 May 2026 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 6 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 May, 20 May, 21 May). IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 590 km/s at 17/2134Z. Total IMF reached 5 nT at 18/2027Z. The maximum southward component of Bz reached -5 nT at 18/2027Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 6667 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (19 May), quiet levels on day two (20 May) and quiet to unsettled levels on day three (21 May). III. Event probabilities 19 May-21 May Class M 40/40/40 Class X 05/05/05 Proton 05/05/05 PCAF green IV. Penticton 10.7 cm Flux Observed 18 May 105 Predicted 19 May-21 May 110/115/115 90 Day Mean 18 May 124 V. Geomagnetic A Indices Observed Afr/Ap 17 May 007/008 Estimated Afr/Ap 18 May 011/015 Predicted Afr/Ap 19 May-21 May 018/021-007/008-007/010 VI. Geomagnetic Activity Probabilities 19 May-21 May A. Middle Latitudes Active 35/20/25 Minor Storm 30/05/05 Major-severe storm 05/01/01 B. High Latitudes Active 10/20/20 Minor Storm 25/30/30 Major-severe storm 60/25/25