2025 Dec 12 2200 UTC
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 346 Issued at 2200Z on 12 Dec 2025

IA. Analysis of Solar Active Regions and Activity from 11/2100Z to
12/2100Z: Solar activity has been at moderate levels for the past 24
hours. There are currently 7 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is likely to be moderate on
day one (13 Dec) and expected to be low with a chance for M-class flares
on days two and three (14 Dec, 15 Dec).

IIA. Geophysical Activity Summary 11/2100Z to 12/2100Z: The geomagnetic
field has been at unsettled to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 509 km/s at 12/0240Z. Total IMF
reached 14 nT at 12/2052Z. The maximum southward component of Bz reached
-14 nT at 12/2051Z. Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 1078 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to minor storm levels on day one (13 Dec), quiet to
active levels on day two (14 Dec) and quiet levels on day three (15
Dec).

III. Event probabilities 13 Dec-15 Dec
Class M 55/45/35
Class X 05/01/01
Proton 05/05/01
PCAF green

IV. Penticton 10.7 cm Flux
Observed 12 Dec 135
Predicted 13 Dec-15 Dec 130/120/120
90 Day Mean 12 Dec 151

V. Geomagnetic A Indices
Observed Afr/Ap 11 Dec 017/026
Estimated Afr/Ap 12 Dec 020/023
Predicted Afr/Ap 13 Dec-15 Dec 015/019-011/012-007/008

VI. Geomagnetic Activity Probabilities 13 Dec-15 Dec
A. Middle Latitudes
Active 45/40/40
Minor Storm 25/20/20
Major-severe storm 05/05/05
B. High Latitudes
Active 10/10/10
Minor Storm 25/25/25
Major-severe storm 65/60/60