Solar activity was at low levels this past week with occasional
B-class and isolated low-level C-class flares. The largest event of
the period was a C1.4/Sf flare from Region 4429 on May 5.
There are currently six numbered regions on the visible disk as 4434
decayed to plage and Region 4428 rotated beyond the western limb as
an E-type group. The remaining regions mostly showed signs of decay.
Region 4425 appeared stable, though full characterization is
difficult due to extreme limb proximity. Region 4429 showed continued
submergence and decay, decreasing in both area and length along with
a total loss of penumbra.
Region 4431 showed some minor new development, with a few small spots
emerging in both polarities following recent decay. Region 4432 had
minor emergence in its intermediate spots, despite an overall gradual
decrease in extent. The remaining regions were mostly stable.
No Earth-directed CMEs were observed in available coronagraph
Flare probabilities increase beginning May 8 as up to two active
regions rotate into view from beyond the eastern limb.
Considering the size of these regions and recent far-side eruptions
seen in coronagraph imagery, solar activity is expected to increase
May 8 – 9 with a chance for M-class (R1-R2/minor-moderate) flares and
a slight chance for X-class (R3/strong or greater) flares.
Solar wind parameters returned to near background levels as transient
coronal mass ejection (CME) influences waned. Solar wind speeds
averaged around 375 km/s. The phi angle was predominantly in a
positive (away) orientation for the majority of the period with a few
short-lived oscillations into a negative (toward) orientation during
the period.
Spaceweather.com reports a big and active sunspot hiding behind the
sun’s northeastern limb is about to reveal itself, rotating into view
this weekend. A dramatic M2-class solar flare on May 7th confirmed
its approach. The unnamed sunspot has produced at least 5 CMEs in
recent days. If this production continues, Earth could soon be in
line for a solar storm.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth’s
Ionosphere, May 7, 2026, by F. K. Janda, OK1HH:
Overall solar activity declined slowly but steadily in late April and
early May. Eruptive activity was low, with active regions mostly and
featuring a simple magnetic field configuration. Geomagnetic activity
increased significantly only on May 4, after which the polarity of
the longitudinal component of the interplanetary magnetic field
returned to positive values. The ionosphere returned to a state
favorable for shortwave propagation since May 6.
Solar activity is likely to remain at current levels, while should
decline shortly and slightly in mid-May. Geomagnetically quiet days
can be expected starting May 10 again. Prior to that, there will be a
slight increase in activity, likely on May 8. No other significant
fluctuations are likely.
The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found
on YouTube. https://www.youtube.com/watch?v=lNcaoB7be-k
The Predicted Planetary A Index for May 9 to May 15 is 10, 6, 5, 5,
5, 5, and 25 with a mean of 8.7. The Predicted Planetary K Index is
3, 2, 2, 2, 2, 2, and 5 with a mean of 2.6. 10.7 centimeter flux is
130, 130, 125, 125, 120, 115, and 120 with a mean of 123.6.
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.