The ARRL Solar Report
The Solar Geophysical Activity Report and Forecast from the
USAF/NOAA indicates that solar activity has been at low levels for
the past 24 hours.
There are currently four numbered sunspot regions on the solar disk.
Solar activity is expected to be low with a chance for M-class
flares on May 10 and 11.
A simultaneous filament eruption produced a narrow Coronal Mass
Ejection (CME) signature that was first observed on May 6, and an
additional slower filament eruption was also observed. Analysis of
the events is ongoing and there was no significant growth or decay
observed in the spotted regions on the visible Sun.
The geomagnetic field is likely to experience periods of active
conditions on May 10 and 11 due to continued Coronal Hole High-Speed
Stream influences (CH HSS).
Geomagnetic field activity is likely to reach G1 (Minor) storm
levels on May 18, and May 29 to 31 due to negative polarity coronal
hole influences. Periods of active conditions are likely on May 16
and 17, and on May 19 to 21 in response to CH HSS influences.
On Spaceweather.com for May 9, there is a video of a "Solar Tornado"
occurring on the Sun's surface.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, May 8, 2025, from F. K. Janda, OK1HH:
"Although we were expecting more activity in the relatively large
sunspot group AR4079 that crossed the central meridian on May 4, it
did not happen. Indeed, its magnetic configuration did not promise
it. Instead, a sufficiently fast and proton - and especially
free-electron-rich solar wind blew from the edges of the coronal
holes, which for most of the past days since the beginning of May
caused not only increased geomagnetic activity, but also increased
attenuation and scattering of radio waves in the ionosphere.
"Only a slight improvement in the situation can be predicted. In a
few days, the only one major active region that we know about thanks
to helioseismology should appear on the eastern limb of the solar
disk. Again, it is likely to be the only one in the disk, while the
small number of remaining ones will more or less not contribute to
the overall level of solar activity.
"It remains the case that solar activity is likely to shift from the
southern hemisphere to the northern hemisphere this year, but this
will probably not yet happen in May."
The latest video report from Dr. Tamitha Skov, WX6SWW, can be found
on YouTube at: https://www.youtube.com/watch?v=XZ7C6ja3ZmE .
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals. For
an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere . Information and
tutorials on propagation can be found at, http://k9la.us/ .
Also, check this:
https://bit.ly/3Rc8Njt
"Understanding Solar Indices" from September 2002 QST.
The Predicted Planetary A Index for May 10 to 16 is 12, 10, 5, 5, 5,
5, and 12, with a mean of 7.7. The Predicted Planetary K Index for
the same period is 4, 3, 2, 2, 2, 2, and 4, with a mean of 2.7.
Predicted 10.7 centimeter flux is 165, 165, 160, 155, 155, 155, and
155, with a mean of 158.6.
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