:Product: 0910RSGA.txt :Issued: 2017 Sep 10 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 253 Issued at 2200Z on 10 Sep 2017 IA. Analysis of Solar Active Regions and Activity from 09/2100Z to 10/2100Z: Solar activity has been at high levels for the past 24 hours. The largest solar event of the period was a X8 event observed at 10/1606Z from old Region 2673 (S09, L=119). There are currently 3 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be moderate with a chance for X-class flares on day one (11 Sep) and expected to be very low with a chance for a C-class flares and a slight chance for an M-class flare on day two (12 Sep) and expected to be very low with a slight chance for a C-class flare on day three (13 Sep). IIA. Geophysical Activity Summary 09/2100Z to 10/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 560 km/s at 10/1015Z. Total IMF reached 6 nT at 10/1935Z. The maximum southward component of Bz reached -4 nT at 10/2020Z. Protons greater than 10 MeV at geosynchronous orbit reached a peak level of 1038 pfu at 10/1845Z. Protons greater than 100 MeV at geosynchronous orbit reached a peak level of 54 pfu at 10/2100Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 7875 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (11 Sep), quiet to active levels on day two (12 Sep) and unsettled to minor storm levels on day three (13 Sep). Protons are expected to cross threshold on day one (11 Sep), are expected to cross threshold on day two (12 Sep) and are likely to cross threshold on day three (13 Sep). III. Event probabilities 11 Sep-13 Sep Class M 80/10/01 Class X 50/01/01 Proton 99/95/65 PCAF red IV. Penticton 10.7 cm Flux Observed 10 Sep 100 Predicted 11 Sep-13 Sep 085/083/081 90 Day Mean 10 Sep 081 V. Geomagnetic A Indices Observed Afr/Ap 09 Sep 006/004 Estimated Afr/Ap 10 Sep 005/006 Predicted Afr/Ap 11 Sep-13 Sep 007/007-010/012-020/030 VI. Geomagnetic Activity Probabilities 11 Sep-13 Sep A. Middle Latitudes Active 15/25/35 Minor Storm 05/10/25 Major-severe storm 01/01/05 B. High Latitudes Active 15/15/10 Minor Storm 20/30/25 Major-severe storm 20/40/60