Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 17 September 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 260 Issued at 2200Z on 17 Sep 2021

IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C3 event observed at 17/0420Z. There are currently 0 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 (18 Sep, 19 Sep, 20 Sep).

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 421 km/s at 17/2055Z. Total IMF reached 14 nT at 17/1748Z. The maximum southward component of Bz reached -13 nT at 17/1812Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 294 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to minor storm levels on day one (18 Sep), quiet to unsettled levels on day two (19 Sep) and quiet levels on day three (20 Sep).

III. Event probabilities 18 Sep-20 Sep
Class M 05/05/05
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 17 Sep 073
Predicted 18 Sep-20 Sep 075/078/080
90 Day Mean 17 Sep 082

V. Geomagnetic A Indices
Observed Afr/Ap 16 Sep 003/004
Estimated Afr/Ap 17 Sep 012/020
Predicted Afr/Ap 18 Sep-20 Sep 014/015-008/010-006/005

VI. Geomagnetic Activity Probabilities 18 Sep-20 Sep
A. Middle Latitudes
Active 40/30/10
Minor Storm 25/10/01
Major-severe storm 05/01/01
B. High Latitudes
Active 10/15/15
Minor Storm 25/30/20
Major-severe storm 60/40/20