Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 20 December 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 354 Issued at 2200Z on 20 Dec 2021

IA. Analysis of Solar Active Regions and Activity from 19/2100Z to 20/2100Z: 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 20/1136Z from Region 2908 (S21W11). There are currently 8 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 day one (21 Dec) and expected to be low with a slight chance for an M-class flare on days two and three (22 Dec, 23 Dec).

IIA. Geophysical Activity Summary 19/2100Z to 20/2100Z: The geomagnetic field has been at quiet to minor storm levels for the past 24 hours. Solar wind speed reached a peak of 631 km/s at 20/1826Z. Total IMF reached 19 nT at 19/2105Z. The maximum southward component of Bz reached -12 nT at 19/2317Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 227 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to active levels on days one and two (21 Dec, 22 Dec) and quiet to unsettled levels on day three (23 Dec).

III. Event probabilities 21 Dec-23 Dec
Class M 25/20/20
Class X 05/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 20 Dec 123
Predicted 21 Dec-23 Dec 124/122/120
90 Day Mean 20 Dec 089

V. Geomagnetic A Indices
Observed Afr/Ap 19 Dec 008/012
Estimated Afr/Ap 20 Dec 013/017
Predicted Afr/Ap 21 Dec-23 Dec 012/016-010/012-008/008

VI. Geomagnetic Activity Probabilities 21 Dec-23 Dec
A. Middle Latitudes
Active 35/25/15
Minor Storm 15/05/01
Major-severe storm 01/01/01
B. High Latitudes
Active 10/15/15
Minor Storm 30/30/25
Major-severe storm 45/30/20