Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 233 Issued at 2200Z on 21 Aug 2023

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C4 event observed at 21/0753Z. There are currently 8 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low with a slight chance for an M-class flare on days one, two, and three (22 Aug, 23 Aug, 24 Aug).

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 686 km/s at 20/2240Z. Total IMF reached 7 nT at 20/2252Z. The maximum southward component of Bz reached -5 nT at 21/0723Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 229 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one, two, and three (22 Aug, 23 Aug, 24 Aug).

III. Event probabilities 22 Aug-24 Aug
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Aug 149
Predicted 22 Aug-24 Aug 150/155/155
90 Day Mean 21 Aug 166

V. Geomagnetic A Indices
Observed Afr/Ap 20 Aug 012/011
Estimated Afr/Ap 21 Aug 008/010
Predicted Afr/Ap 22 Aug-24 Aug 008/010-008/010-007/010

VI. Geomagnetic Activity Probabilities 22 Aug-24 Aug
A. Middle Latitudes
Active 15/15/15
Minor Storm 05/05/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/20/20
Major-severe storm 20/20/20

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