:Product: 1221RSGA.txt
:Issued: 2025 Dec 21 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 355 Issued at 2200Z on 21 Dec 2025

IA.  Analysis of Solar Active Regions and Activity from 20/2100Z to
21/2100Z: Solar activity has been at moderate levels for the past 24
hours. There are currently 5 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 (22 Dec, 23 Dec,
24 Dec).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic
field has been at unsettled to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 723 km/s at 21/2028Z. Total IMF
reached 15 nT at 21/1128Z. The maximum southward component of Bz reached
-11 nT at 21/0544Z.  Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 2257 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at unsettled to minor storm levels on day one (22 Dec), quiet to
minor storm levels on day two (23 Dec) and unsettled to active levels on
day three (24 Dec).

III.  Event probabilities 22 Dec-24 Dec
Class M    25/25/30
Class X    01/01/01
Proton     01/01/01
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 Dec 124
Predicted   22 Dec-24 Dec 130/135/140
90 Day Mean        21 Dec 148

V.  Geomagnetic A Indices
Observed Afr/Ap 20 Dec  004/006
Estimated Afr/Ap 21 Dec  016/021
Predicted Afr/Ap 22 Dec-24 Dec  019/028-015/022-010/020

VI.  Geomagnetic Activity Probabilities 22 Dec-24 Dec
A.  Middle Latitudes
Active                35/35/30
Minor Storm           30/30/15
Major-severe storm    10/10/01
B.  High Latitudes
Active                10/10/15
Minor Storm           20/20/30
Major-severe storm    65/65/40
