:Product: 0527RSGA.txt :Issued: 2021 May 27 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 147 Issued at 2200Z on 27 May 2021 IA. Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C3 event observed at 26/2124Z from Region 2826 (N24W60). There are currently 2 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is expected to be very low with a chance for a C-class flares and a slight chance for an M-class flare on days one and two (28 May, 29 May) and expected to be very low with a slight chance for a C-class flare on day three (30 May). IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 448 km/s at 27/2035Z. Total IMF reached 16 nT at 27/0254Z. The maximum southward component of Bz reached -11 nT at 27/0518Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 187 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (28 May) and quiet levels on days two and three (29 May, 30 May). III. Event probabilities 28 May-30 May Class M 10/10/01 Class X 01/01/01 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 27 May 083 Predicted 28 May-30 May 083/081/080 90 Day Mean 27 May 077 V. Geomagnetic A Indices Observed Afr/Ap 26 May 012/014 Estimated Afr/Ap 27 May 017/021 Predicted Afr/Ap 28 May-30 May 008/010-005/005-007/008 VI. Geomagnetic Activity Probabilities 28 May-30 May A. Middle Latitudes Active 20/10/15 Minor Storm 05/01/05 Major-severe storm 01/01/01 B. High Latitudes Active 15/15/15 Minor Storm 30/20/25 Major-severe storm 30/10/25