Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 21 December 2020

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 356 Issued at 2200Z on 21 Dec 2020

IA. Analysis of Solar Active Regions and Activity from 20/2100Z to 21/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 1 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be very low with a slight chance for a C-class flare 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 unsettled levels for the past 24 hours. Solar wind speed reached a peak of 407 km/s at 21/1357Z. Total IMF reached 12 nT at 21/2042Z. The maximum southward component of Bz reached -12 nT at 21/2056Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 265 pfu.

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

III. Event probabilities 22 Dec-24 Dec
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 21 Dec 080
Predicted 22 Dec-24 Dec 080/080/080
90 Day Mean 21 Dec 083

V. Geomagnetic A Indices
Observed Afr/Ap 20 Dec 004/003
Estimated Afr/Ap 21 Dec 009/011
Predicted Afr/Ap 22 Dec-24 Dec 008/010-012/018-014/015

VI. Geomagnetic Activity Probabilities 22 Dec-24 Dec
A. Middle Latitudes
Active 25/35/35
Minor Storm 05/20/20
Major-severe storm 01/05/05
B. High Latitudes
Active 15/10/10
Minor Storm 30/25/30
Major-severe storm 30/55/50