Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 23 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 266 Issued at 2200Z on 23 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 5 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be low with a slight chance for an M-class flare on days one, two, and three (24 Sep, 25 Sep, 26 Sep).

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 404 km/s at 23/1621Z. Total IMF reached 9 nT at 23/2056Z. The maximum southward component of Bz reached -5 nT at 23/0518Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1247 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on day one (24 Sep), quiet to unsettled levels on day two (25 Sep) and quiet to minor storm levels on day three (26 Sep).

III. Event probabilities 24 Sep-26 Sep
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 23 Sep 090
Predicted 24 Sep-26 Sep 090/092/095
90 Day Mean 23 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 22 Sep 011/012
Estimated Afr/Ap 23 Sep 010/011
Predicted Afr/Ap 24 Sep-26 Sep 011/015-007/008-012/020

VI. Geomagnetic Activity Probabilities 24 Sep-26 Sep
A. Middle Latitudes
Active 30/35/45
Minor Storm 10/15/30
Major-severe storm 01/01/05
B. High Latitudes
Active 15/15/05
Minor Storm 30/30/20
Major-severe storm 40/50/75