Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 30 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 273 Issued at 2200Z on 30 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 29/2100Z to 30/2100Z: 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 29/2156Z from Region 2877 (S16W40). 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, two, and three (01 Oct, 02 Oct, 03 Oct).

IIA. Geophysical Activity Summary 29/2100Z to 30/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 504 km/s at 30/2050Z. Total IMF reached 14 nT at 30/1818Z. The maximum southward component of Bz reached -9 nT at 30/1811Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 616 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (01 Oct), quiet to active levels on day two (02 Oct) and quiet to unsettled levels on day three (03 Oct).

III. Event probabilities 01 Oct-03 Oct
Class M 10/10/10
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 30 Sep 095
Predicted 01 Oct-03 Oct 095/095/095
90 Day Mean 30 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 29 Sep 004/004
Estimated Afr/Ap 30 Sep 009/011
Predicted Afr/Ap 01 Oct-03 Oct 018/024-008/010-008/008

VI. Geomagnetic Activity Probabilities 01 Oct-03 Oct
A. Middle Latitudes
Active 45/40/25
Minor Storm 30/20/05
Major-severe storm 05/05/01
B. High Latitudes
Active 05/10/15
Minor Storm 20/30/25
Major-severe storm 70/60/30