Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 19 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 262 Issued at 2200Z on 19 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 18/2100Z to 19/2100Z: 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 19/0115Z from Region 2871 (S28E61). There are currently 1 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 days one, two, and three (20 Sep, 21 Sep, 22 Sep).

IIA. Geophysical Activity Summary 18/2100Z to 19/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 413 km/s at 18/2215Z. Total IMF reached 5 nT at 19/1146Z. The maximum southward component of Bz reached -2 nT at 18/2233Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 154 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on day one (20 Sep) and quiet to unsettled levels on days two and three (21 Sep, 22 Sep).

III. Event probabilities 20 Sep-22 Sep
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 19 Sep 075
Predicted 20 Sep-22 Sep 075/075/075
90 Day Mean 19 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 18 Sep 014/014
Estimated Afr/Ap 19 Sep 003/003
Predicted Afr/Ap 20 Sep-22 Sep 006/005-007/008-008/008

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