Solar activity has been at low levels with only minor C-class
flaring through April 24, 2025, and is expected to be moderate with
a chance of M-class flares (R1-R2, Minor-Moderate) through April 26.
No Earth-directed Coronal Mass Ejections (CMEs) have been observed.
A southwest CME was observed on April 23 and is considered to be
far-side due to the lack of any on-disk plasma motion/flare
activity.
 
Solar wind parameters continued to be slightly enhanced due to the
Coronal Hole High-Speed Streams (CH HSS) associated with the
positive polarity coronal holes in the southern hemisphere.  Solar
wind parameters are expected to continue to be influenced by
positive polarity, with CH HSS conditions through April 26.  Nominal
conditions are expected thereafter.

On April 25, Spaceweather.com reported the Earth was struck by an
interplanetary shockwave on April 24 around 0700 UTC. An
interplanetary shock wave is an abrupt change in the solar wind -
probably caused by the Coronal Mass Ejection.

Overall, solar activity remained at low levels.  Region AR4064
remained the largest sunspot group on the disk.  The regions
intermediate spots grew in penumbral area over the past 24 hours.

The geomagnetic field is expected to remain at mostly quiet to
unsettled levels, with active conditions likely on April 27 due to
the influence from multiple positive polarity CH HSS.

There are currently 11 numbered sunspot regions on the solar disk.

Solar activity is expected to be low with a chance for M-class
flares on April 26 and 27.

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 April 26 to May 2 is 8, 8, 6, 6,
6, 25, and 35, with a mean of 13.4.  The Predicted Planetary K Index
is 3, 3, 2, 2, 2, 5, and 6, with a mean of 3.3.  Predicted 10.7
centimeter flux is 165, 165, 170, 170, 170, 170, and 175, with a
mean of 169.3.