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

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 351 Issued at 2200Z on 17 Dec 2021

IA. Analysis of Solar Active Regions and Activity from 16/2100Z to 17/2100Z: 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 17/0051Z from Region 2911 (N19E54). There are currently 6 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 (18 Dec, 19 Dec, 20 Dec).

IIA. Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 477 km/s at 16/2152Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 159 pfu.

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

III. Event probabilities 18 Dec-20 Dec
Class M 25/25/25
Class X 05/05/05
Proton 05/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 17 Dec 121
Predicted 18 Dec-20 Dec 121/121/122
90 Day Mean 17 Dec 088

V. Geomagnetic A Indices
Observed Afr/Ap 16 Dec 005/005
Estimated Afr/Ap 17 Dec 006/007
Predicted Afr/Ap 18 Dec-20 Dec 007/008-006/008-009/010

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