:Product: 0318RSGA.txt :Issued: 2026 Mar 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 77 Issued at 2200Z on 18 Mar 2026 IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at moderate levels for the past 24 hours. There are currently 5 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares and a slight chance for an X-class flare on days one, two, and three (19 Mar, 20 Mar, 21 Mar). IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 466 km/s at 17/2106Z. Total IMF reached 5 nT at 17/2320Z. The maximum southward component of Bz reached -4 nT at 18/0901Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 2949 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to major storm levels on day one (19 Mar), unsettled to major storm levels on day two (20 Mar) and active to major storm levels on day three (21 Mar). Protons have a slight chance of crossing threshold on days one, two, and three (19 Mar, 20 Mar, 21 Mar). III. Event probabilities 19 Mar-21 Mar Class M 35/35/35 Class X 10/10/10 Proton 10/10/10 PCAF green IV. Penticton 10.7 cm Flux Observed 18 Mar 113 Predicted 19 Mar-21 Mar 115/115/110 90 Day Mean 18 Mar 142 V. Geomagnetic A Indices Observed Afr/Ap 17 Mar 004/004 Estimated Afr/Ap 18 Mar 006/007 Predicted Afr/Ap 19 Mar-21 Mar 018/028-028/044-032/050 VI. Geomagnetic Activity Probabilities 19 Mar-21 Mar A. Middle Latitudes Active 25/25/25 Minor Storm 30/35/35 Major-severe storm 25/30/35 B. High Latitudes Active 05/05/05 Minor Storm 20/15/15 Major-severe storm 75/75/85