:Product: 1217RSGA.txt :Issued: 2023 Dec 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 351 Issued at 2200Z on 17 Dec 2023 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. The largest solar event of the period was a M1 event observed at 17/2017Z from Region 3514 (N05W94). There are currently 8 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 day one (18 Dec) and expected to be low with a slight chance for an M-class flare on days two and three (19 Dec, 20 Dec). IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at unsettled to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 565 km/s at 17/0955Z. Total IMF reached 16 nT at 17/1439Z. The maximum southward component of Bz reached -14 nT at 17/1505Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 147 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (18 Dec) and quiet to active levels on days two and three (19 Dec, 20 Dec). III. Event probabilities 18 Dec-20 Dec Class M 25/10/10 Class X 05/01/01 Proton 05/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 17 Dec 155 Predicted 18 Dec-20 Dec 147/145/140 90 Day Mean 17 Dec 149 V. Geomagnetic A Indices Observed Afr/Ap 16 Dec 010/011 Estimated Afr/Ap 17 Dec 025/035 Predicted Afr/Ap 18 Dec-20 Dec 013/015-013/015-011/012 VI. Geomagnetic Activity Probabilities 18 Dec-20 Dec A. Middle Latitudes Active 30/25/25 Minor Storm 15/10/10 Major-severe storm 01/01/01 B. High Latitudes Active 15/15/15 Minor Storm 20/20/20 Major-severe storm 20/20/25