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Solar activity will likely continue at moderate levels with isolated
M class flares through September 6 due to the combined flare
potential of Regions AR4197 and AR4207. Probabilities decrease to
just a chance for M class flares on September 7 as AR4197 moves
beyond the western limb.  An enhanced solar wind regime is
anticipated to continue into September 6 due to a positive polarity
coronal hole high speed stream.  On September 7, High Speed Stream
activity combined with the arrival of the September 4th CME is
likely to cause further G1, or Minor, storming levels with a chance
for G2, or Moderate, levels.  Weekly Commentary on the Sun, the
Magnetosphere, and the Earths Ionosphere, September 4, 2025, by F.
K. Janda, OK1HH, As soon as we begin to think that we are starting
to understand what is happening on the Sun and in its vicinity,
where we and Earth are located, Mother Nature shows us that it is
not that simple. A small example, while we were observing the
extensive active region 4197 on the Sun, an eruption occurred in
another, much smaller and less conspicuous region, AR4199, which had
a key influence on the events of the following days. It happened on
the evening of Saturday, August 30, very close to the solar equator
and the central meridian, so it was directed towards Earth.  The
forecasts of further developments from all forecasting centers were
identical, the CME would arrive at Earth on September 1 in the late
afternoon to evening hours and cause a G2 class magnetic storm,
accompanied by auroras. And so, it happened.  As predicted, the
geomagnetic disturbance continued on September 2.  This was followed
by a relatively rapid calm, and by September 4, the state of the
Earths magnetosphere and ionosphere began to approach what we are
used to at the end of summer and beginning of autumn, in other
words, there was a noticeable improvement in the conditions for
ionospheric shortwave propagation.  In further developments, the
Earth will be affected by another surge of solar wind on September
6. But this should come as no surprise, as it is a regularly
recurring passage of the Earth through a stream of intensified solar
wind linked to active areas on the Sun. The entire system, together
with the Sun, rotates once every approximately 27 days. Therefore,
predictions of the onset of disturbances are relatively reliable.
The latest report from Dr. Tamitha Skov, WX6SWW, can be found on
Youtube.  The predicted Planetary A Index for September 6 to 12 is
8, 12, 12, 12, 10, 5, and 5, with a mean of 9.1  The predicted
Planetary K Index is 3, 4, 4, 4, 4, 2, and 2, with a mean of 3.3.
10.7 centimeter flux is 175, 160, 140, 130, 125, 125, and 120, with
a mean of 139.3.  Links to articles or other websites mentioned in
this bulletin can be found in teleprinter, packet, and Internet
versions of 2025 Propagation Forecast Bulletin ARLP033.

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