Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 264 Issued at 2200Z on 21 Sep 2023

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at high levels for the past 24 hours. The largest solar event of the period was a M8 event observed at 21/1254Z from Region 3435 (N08E16). There are currently 11 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is likely to be moderate with a slight chance for an X-class flare on days one, two, and three (22 Sep, 23 Sep, 24 Sep).

IIA. Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic field has been at quiet to active levels for the past 24 hours. Solar wind speed reached a peak of 474 km/s at 20/2119Z. Total IMF reached 5 nT at 21/0709Z. The maximum southward component of Bz reached -4 nT at 21/1239Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1416 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on day one (22 Sep), unsettled to minor storm levels on day two (23 Sep) and quiet to minor storm levels on day three (24 Sep).

III. Event probabilities 22 Sep-24 Sep
Class M 55/55/55
Class X 10/10/10
Proton 05/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Sep 168
Predicted 22 Sep-24 Sep 162/162/165
90 Day Mean 21 Sep 161

V. Geomagnetic A Indices
Observed Afr/Ap 20 Sep 015/020
Estimated Afr/Ap 21 Sep 008/009
Predicted Afr/Ap 22 Sep-24 Sep 011/015-016/022-018/022

VI. Geomagnetic Activity Probabilities 22 Sep-24 Sep
A. Middle Latitudes
Active 35/35/35
Minor Storm 15/25/20
Major-severe storm 01/05/05
B. High Latitudes
Active 10/10/15
Minor Storm 30/25/20
Major-severe storm 55/65/30

Space Weather