08/01/2026
Solar activity has remained at low levels. Region 4494 exhibited decay in its
trailing spots as its flare activity subsided. Region 4498 rotated into better
viewing positioning, revealing mixed polarity just behind its large leading
spot, and was responsible for a handful of low-level C-class flares.
Region 4499 underwent evolution, gaining additional spots and producing a
low-level C-class flare. Region 4501 rapidly emerged this period, developed
rudimentary penumbra on its leading and trailing spots, produced a low-level
C-class flare and was thus subsequently numbered. The remaining numbered active
regions were unremarkable in relation.
No Earth-directed CMEs were observed in available coronagraph imagery.
Solar activity is expected to be low with a chance for M-class flares (R1-R2,
minor-moderate) through August 1.
Solar wind parameters were at nominal levels. Solar wind speeds roughly ranged
from 310 km/s to 401 km/s. A disturbed solar wind environment will likely return
July 30 due to the prospect of combined positive polarity coronal high speed
stream (CH HSS) effects and coronal mass ejection (CME) arrivals from events
that left the Sun on July 26 - 27. An additional disturbance is likely on August
1 with the arrival of an additional CME that left the Sun late on July 27.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere,
July 30, 2026, by F. K. Janda, OK1HH:
During the last third of July, solar activity initially rose, while remained at
a higher level until the end of the month. Although solar flares occasionally
reached moderate intensity, while were exceptionally accompanied by coronal mass
ejections, the Earth was not affected by them (though this could still happen by
the end of July or early August, partly because there is a coronal hole in the
southwestern part of the disk). There is only one active region on the far side
of the Sun. Therefore, as the nine regions currently being observed fade,
overall activity will decline shortly after the beginning of August.
Shorter periods of increased geomagnetic activity may still occur in late July
and at the beginning and end of the first third of August. Following the
expected decline in solar activity, these will be followed at irregular
intervals by shorter periods of deteriorated ionospheric conditions for
shortwave propagation.
The predicted Planetary A Index for July 31 to August 6 is 8, 5, 5, 5, 12, 15,
and 10, with a mean of 8.6. The predicted Planetary K Index is 3, 2, 2, 2, 4, 3,
and 3, with a mean of 2.7. Predicted 10.7 centimeter flux is 135, 130, 125, 125,
125, 120, and 125, with a mean of 126.4.
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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