Joint USAF/NOAA Solar Geophysical Activity Report and Forecast 18 December 2021

Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 352 Issued at 2200Z on 18 Dec 2021

IA. Analysis of Solar Active Regions and Activity from 17/2100Z to 18/2100Z: Solar activity has been at low levels for the past 24 hours. The largest solar event of the period was a C6 event observed at 18/1801Z. 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 (19 Dec, 20 Dec, 21 Dec).

IIA. Geophysical Activity Summary 17/2100Z to 18/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 379 km/s at 17/2115Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 189 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on days one and two (19 Dec, 20 Dec) and quiet to active levels on day three (21 Dec).

III. Event probabilities 19 Dec-21 Dec
Class M 25/25/25
Class X 05/05/05
Proton 05/05/05
PCAF green

IV. Penticton 10.7 cm Flux
Observed 18 Dec 121
Predicted 19 Dec-21 Dec 122/123/125
90 Day Mean 18 Dec 088

V. Geomagnetic A Indices
Observed Afr/Ap 17 Dec 002/001
Estimated Afr/Ap 18 Dec 004/005
Predicted Afr/Ap 19 Dec-21 Dec 006/008-009/010-013/016

VI. Geomagnetic Activity Probabilities 19 Dec-21 Dec
A. Middle Latitudes
Active 10/20/30
Minor Storm 01/05/15
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 20/25/30
Major-severe storm 20/25/45