Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 27 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 270 Issued at 2200Z on 27 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 26/2100Z to 27/2100Z: Solar activity has been at very low levels for the past 24 hours. 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 on day one (28 Sep) and expected to be very low with a slight chance for a C-class flare on days two and three (29 Sep, 30 Sep).

IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 404 km/s at 27/2059Z. Total IMF reached 14 nT at 27/1902Z. The maximum southward component of Bz reached -5 nT at 27/0145Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 696 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to major storm levels on day one (28 Sep), quiet to minor storm levels on day two (29 Sep) and quiet to unsettled levels on day three (30 Sep).

III. Event probabilities 28 Sep-30 Sep
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 27 Sep 085
Predicted 28 Sep-30 Sep 086/084/080
90 Day Mean 27 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 26 Sep 002/002
Estimated Afr/Ap 27 Sep 013/021
Predicted Afr/Ap 28 Sep-30 Sep 023/030-013/015-007/008

VI. Geomagnetic Activity Probabilities 28 Sep-30 Sep
A. Middle Latitudes
Active 30/45/15
Minor Storm 40/30/05
Major-severe storm 15/05/01
B. High Latitudes
Active 05/05/20
Minor Storm 20/20/25
Major-severe storm 75/70/20