07/10/2026
Solar activity reached moderate levels with an M1.5/1N flare on July 8 from
Region 4482.
There are currently five numbered regions on the visible disk. Region 4482
demonstrated continued growth and developed a delta spot within its trailing
spot group. Region 4485 displayed new flux emergence. Regions 4486 and 4487 were
newly numbered during the period. Region 4481 was stable and remained an
unremarkable unipolar group.
No Earth-directed CMEs were observed in available coronagraph imagery.
Solar activity is expected to remain at low levels through July 11, with a high
chance for M-class (R1-R2/minor-moderate) flares and a slight chance for X-class
(R3/strong and greater) events. This flare probability is almost entirely due to
the complexity and potential of Region 4482.
Solar wind parameters reflected near ambient background conditions. Solar wind
speeds were generally near 400 km/s. The phi angle was predominantly in the
positive sector.
Enhancements are anticipated to begin on July 9 and continue through July 11
with the arrival of a co-rotating interaction region (CIR) ahead of a negative
polarity coronal hole high-speed stream (-CH HSS).
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere,
July 9, 2026, by F. K. Janda, OK1HH:
The power flux of solar radio noise at a frequency of 2800 MHz (at a wavelength
of 10.7 cm), which is measured precisely every day at noon local time in
Penticton, Canada, and is referred to as the "solar flux," remains at a
relatively low level. The reason is that the number of observed sunspot groups
on the solar disk dropped to just three on July 7, the lowest number recorded
during a single solar rotation (the following day, their number increased to
five). The largest active region, NOAA 4482, which we observe in the southeast
of the solar disk, has not changed significantly in size and continues to
produce moderate-intensity flares on a regular basis. All three coronal holes
are currently relatively far from it. The intensity of the solar wind is
changing only slightly; periods of increased geomagnetic activity alternate with
quiet days, making it impossible to accurately predict future developments.
A more pronounced increase in solar activity is expected in the second half of
July (with a gradual increase in solar flux up to 180 s.f.u.). More significant
geomagnetic activity can be expected if major solar flares occur, especially if
they occur near or west of the central meridian. This is likely to happen
sometime in the second half of July.
The predicted Planetary A Index for July 11 to 17 is 12, 8, 5, 5, 5, 10, and 8,
with a mean of 7.6. The predicted Planetary K Index is 4, 3, 2, 2, 2, 3, and 3,
with a mean of 2.7. Predicted 10.7 centimeter flux is 125, 120, 125, 130, 135,
135, and 135, with a mean of 129.3.
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation[1] and the ARRL Technical Information Service
web page at, http://arrl.org/propagation-of-rf-signals[2]. For an explanation of
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere[3] . Information and
tutorials on propagation can be found at, http://k9la.us/[4] .
Also, check this:
https://bit.ly/3Rc8Njt[5]
"Understanding Solar Indices" from September 2002 QST.
[1] http://www.arrl.org/propagation
[2] http://arrl.org/propagation-of-rf-signals
[3] http://arrl.org/the-sun-the-earth-the-ionosphere
[4] http://k9la.us/
[5] https://bit.ly/3Rc8Njt
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