2025 Dec 04 2200 UTC
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 338 Issued at 2200Z on 04 Dec 2025

IA. Analysis of Solar Active Regions and Activity from 03/2100Z to
04/2100Z: Solar activity has been at high levels for the past 24 hours.
There are currently 7 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is expected to be moderate
with a chance for X-class flares on days one, two, and three (05 Dec, 06
Dec, 07 Dec).

IIA. Geophysical Activity Summary 03/2100Z to 04/2100Z: The geomagnetic
field has been at active to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 771 km/s at 04/1112Z. Total IMF
reached 22 nT at 03/2231Z. The maximum southward component of Bz reached
-13 nT at 04/0226Z. Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 446 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at unsettled to active levels on day one (05 Dec), quiet to active
levels on day two (06 Dec) and quiet to minor storm levels on day three
(07 Dec). Protons have a slight chance of crossing threshold on days
one, two, and three (05 Dec, 06 Dec, 07 Dec).

III. Event probabilities 05 Dec-07 Dec
Class M 75/75/75
Class X 25/25/25
Proton 15/15/15
PCAF green

IV. Penticton 10.7 cm Flux
Observed 04 Dec 220
Predicted 05 Dec-07 Dec 220/220/215
90 Day Mean 04 Dec 146

V. Geomagnetic A Indices
Observed Afr/Ap 03 Dec 020/033
Estimated Afr/Ap 04 Dec 022/034
Predicted Afr/Ap 05 Dec-07 Dec 015/020-010/012-012/018

VI. Geomagnetic Activity Probabilities 05 Dec-07 Dec
A. Middle Latitudes
Active 35/30/40
Minor Storm 20/15/25
Major-severe storm 05/01/05
B. High Latitudes
Active 10/15/10
Minor Storm 30/30/20
Major-severe storm 55/45/65