Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 24 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 267 Issued at 2200Z on 24 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 23/2100Z to 24/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C2 event observed at 24/0701Z from Region 2871 (S28E01). There are currently 5 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 on days one, two, and three (25 Sep, 26 Sep, 27 Sep).

IIA. Geophysical Activity Summary 23/2100Z to 24/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 511 km/s at 24/0830Z. Total IMF reached 9 nT at 23/2309Z. The maximum southward component of Bz reached -6 nT at 24/0635Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 309 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (25 Sep), quiet to minor storm levels on day two (26 Sep) and unsettled to major storm levels on day three (27 Sep).

III. Event probabilities 25 Sep-27 Sep
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 24 Sep 088
Predicted 25 Sep-27 Sep 088/086/082
90 Day Mean 24 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 23 Sep 010/008
Estimated Afr/Ap 24 Sep 007/010
Predicted Afr/Ap 25 Sep-27 Sep 009/010-011/018-020/028

VI. Geomagnetic Activity Probabilities 25 Sep-27 Sep
A. Middle Latitudes
Active 25/35/30
Minor Storm 10/35/40
Major-severe storm 01/10/20
B. High Latitudes
Active 15/05/05
Minor Storm 25/25/20
Major-severe storm 35/70/75