Joint USAF/NOAA Solar Geophysical Activity Report and Forecast. 25 December 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 359 Issued at 2200Z on 25 Dec 2021

IA. Analysis of Solar Active Regions and Activity from 24/2100Z to 25/2100Z: 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 25/1905Z from Region 2918 (N19E11). There are currently 7 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be low with a slight chance for an M-class flare on days one, two, and three (26 Dec, 27 Dec, 28 Dec).

IIA. Geophysical Activity Summary 24/2100Z to 25/2100Z: The geomagnetic field has been at quiet to unsettled levels for the past 24 hours. Solar wind speed reached a peak of 530 km/s at 25/1830Z. Total IMF reached 6 nT at 25/1054Z. The maximum southward component of Bz reached -5 nT at 25/0715Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1352 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (26 Dec, 27 Dec) and quiet to active levels on day three (28 Dec).

III. Event probabilities 26 Dec-28 Dec
Class M 15/15/15
Class X 01/01/01
Proton 01/01/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 25 Dec 131
Predicted 26 Dec-28 Dec 130/130/130
90 Day Mean 25 Dec 091

V. Geomagnetic A Indices
Observed Afr/Ap 24 Dec 003/003
Estimated Afr/Ap 25 Dec 008/010
Predicted Afr/Ap 26 Dec-28 Dec 009/010-008/008-011/012

VI. Geomagnetic Activity Probabilities 26 Dec-28 Dec
A. Middle Latitudes
Active 25/20/35
Minor Storm 05/05/15
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 25/25/30
Major-severe storm 30/25/45