Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 26 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 269 Issued at 2200Z on 26 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 25/2100Z to 26/2100Z: 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 26/1124Z from Region 2871 (S28W27). There are currently 4 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be low on days one, two, and three (27 Sep, 28 Sep, 29 Sep).

IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 501 km/s at 25/2327Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 288 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to major storm levels on day one (27 Sep) and quiet to active levels on days two and three (28 Sep, 29 Sep).

III. Event probabilities 27 Sep-29 Sep
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 26 Sep 086
Predicted 27 Sep-29 Sep 086/086/084
90 Day Mean 26 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 25 Sep 007/006
Estimated Afr/Ap 26 Sep 004/004
Predicted Afr/Ap 27 Sep-29 Sep 019/028-014/015-010/012

VI. Geomagnetic Activity Probabilities 27 Sep-29 Sep
A. Middle Latitudes
Active 30/30/30
Minor Storm 40/15/10
Major-severe storm 20/01/01
B. High Latitudes
Active 05/15/15
Minor Storm 20/30/30
Major-severe storm 75/45/40