Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 28 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 271 Issued at 2200Z on 28 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 27/2100Z to 28/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C1 event observed at 28/0634Z. There are currently 4 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be very low with a slight chance for a C-class flare on days one, two, and three (29 Sep, 30 Sep, 01 Oct).

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 548 km/s at 28/1209Z. Total IMF reached 13 27/2235Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 290 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (29 Sep, 30 Sep) and quiet to minor storm levels on day three (01 Oct).

III. Event probabilities 29 Sep-01 Oct
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 28 Sep 089
Predicted 29 Sep-01 Oct 088/084/082
90 Day Mean 28 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 27 Sep 006/006
Estimated Afr/Ap 28 Sep 010/010
Predicted Afr/Ap 29 Sep-01 Oct 009/010-011/012-018/024

VI. Geomagnetic Activity Probabilities 29 Sep-01 Oct
A. Middle Latitudes
Active 30/35/45
Minor Storm 10/10/30
Major-severe storm 01/01/05
B. High Latitudes
Active 15/15/05
Minor Storm 30/30/20
Major-severe storm 40/45/70