Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 December 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 355 Issued at 2200Z on 21 Dec 2021

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at moderate levels for the past 24 hours. The largest solar event of the period was a M1 event observed at 21/1144Z from Region 2916 (S18E82). There are currently 10 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low with a chance for M-class flares on days one, two, and three (22 Dec, 23 Dec, 24 Dec).

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 638 km/s at 20/2225Z. Total IMF reached 6 nT at 20/2106Z. The maximum southward component of Bz reached -5 nT at 21/0049Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 962 pfu.

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

III. Event probabilities 22 Dec-24 Dec
Class M 25/25/25
Class X 05/05/05
Proton 05/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Dec 137
Predicted 22 Dec-24 Dec 136/134/134
90 Day Mean 21 Dec 090

V. Geomagnetic A Indices
Observed Afr/Ap 20 Dec 013/011
Estimated Afr/Ap 21 Dec 009/011
Predicted Afr/Ap 22 Dec-24 Dec 008/008-012/016-016/018

VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec
A. Middle Latitudes
Active 25/35/35
Minor Storm 05/20/25
Major-severe storm 01/05/05
B. High Latitudes
Active 15/10/10
Minor Storm 30/25/25
Major-severe storm 30/55/60