:Product: 0817RSGA.txt
:Issued: 2026 Aug 17 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 229 Issued at 2200Z on 17 Aug 2026

IA.  Analysis of Solar Active Regions and Activity from 16/2100Z to
17/2100Z: Solar activity has been at low 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 on days one, two, and three (18 Aug, 19 Aug,
20 Aug).

IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z: The geomagnetic
field has been at quiet to active levels for the past 24 hours. Solar
wind speed reached a peak of 396 km/s at 17/2033Z. Total IMF reached 13
nT at 17/2019Z. The maximum southward component of Bz reached -12 nT at
17/2014Z.  Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 451 pfu.
IIB.  Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet to active levels on days one and three (18 Aug, 20 Aug)
and quiet to minor storm levels on day two (19 Aug).

III.  Event probabilities 18 Aug-20 Aug
Class M    35/35/35
Class X    05/05/05
Proton     05/05/05
PCAF       green

IV.  Penticton 10.7 cm Flux
Observed           17 Aug 124
Predicted   18 Aug-20 Aug 125/130/130
90 Day Mean        17 Aug 132

V.  Geomagnetic A Indices
Observed Afr/Ap 16 Aug   NA/004
Estimated Afr/Ap 17 Aug  008/010
Predicted Afr/Ap 18 Aug-20 Aug  014/016-016/020-014/015

VI.  Geomagnetic Activity Probabilities 18 Aug-20 Aug
A.  Middle Latitudes
Active                40/40/35
Minor Storm           20/25/15
Major-severe storm    05/05/01
B.  High Latitudes
Active                10/10/15
Minor Storm           30/30/35
Major-severe storm    50/55/40