:Product: Report of Solar-Geophysical Activity
:Issued: 2026 Aug 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 233 Issued at 2200Z on 21 Aug 2026

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 4 numbered sunspot regions on the disk.
IB.  Solar Activity Forecast: Solar activity is expected to be low with
a chance for M-class flares and a slight chance for an X-class flare on
days one, two, and three (22 Aug, 23 Aug, 24 Aug).

IIA.  Geophysical Activity Summary 20/2100Z to 21/2100Z: The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed reached a peak of 567 km/s. Total IMF reached 4 nT. The
maximum southward component of Bz reached -3 nT.  Electrons greater than
2 MeV at geosynchronous orbit reached a peak level of 1546 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to unsettled levels on days one and two (22 Aug, 23 Aug)
and quiet levels on day three (24 Aug).

III.  Event probabilities 22 Aug-24 Aug
Class M    40/40/40
Class X    10/10/10
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           21 Aug 126
Predicted   22 Aug-24 Aug 120/120/115
90 Day Mean        21 Aug 132

V.  Geomagnetic A Indices
Observed Afr/Ap 20 Aug  011/011
Estimated Afr/Ap 21 Aug  009/011
Predicted Afr/Ap 22 Aug-24 Aug  009/010-008/008-006/005

VI.  Geomagnetic Activity Probabilities 22 Aug-24 Aug
A.  Middle Latitudes
Active                25/25/10
Minor Storm           05/05/05
Major-severe storm    01/01/01
B.  High Latitudes
Active                20/20/15
Minor Storm           30/30/20
Major-severe storm    30/25/15