08/15/2025

Solar activity has been at low levels with mostly weak C-class flares observed from Regions 4172 and 4180.ÿ The largest flare of the period was a C6.8/Sf at 15/1037 UTC from Region 4172.ÿ There are 12 regions on the disk with most being simple in magnetic complexity.ÿ Region 4172 remained the largest region on the disk and continued to decay with its magnetic field decreasing in complexity. All remaining regions were quiet and stable.

No Earth-directed CMEs were observed in available coronagraph imagery. Solar activity is likely to continue at low levels through 17 August.ÿ Despite their decreasing activity, Region 4172 will help maintain a slight chance (35%) for isolated M-class flares (R1-2/Minor-Moderate radio blackouts) in the forecast through 15 August.ÿ Chances decrease to 30% as the region moves beyond the western limb.

Waning influences from the CH HSS will steadily decrease the flux of 2 MeV electrons, but concentrations at geostationary orbit will remain high most likely through 17 August.ÿ Last rotation, electrons remained significantly above the 1,000 pfu threshold for seven day with diurnal maximas above threshold for 11 days.

Solar activity is expected to be at predominately low levels with M-class flare (R1-R2/Minor-Moderate events) activity likely over 11 August to 06 September.

No proton events are expected at geosynchronous orbit, barring significant flare activity.

Geomagnetic field activity is expected to reach active levels on 11 August due to waning positive polarity CH HSS influence.ÿ Periods of minor storming are likely on 18-20 August, with periods of active conditions likely on 22 August, due to negative polarity CH HSS influence.ÿ Active conditions are likely again on 28 August in response to anticipated negative polarity CH HSS influence. Periods of moderate storming are likely on 05 September, with active levels likely on 04 and 06 September, due to positive polarity CH HSS influence.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for August 14, 2025 by F. K. Janda, OK1HH:

The overall level of solar activity did not change significantly in August. Medium-size flares were observed almost daily in one or two sunspot groups, while the parameters of the solar wind were most influenced by a coronal hole in the southwestern part of the solar disk.ÿ This clear situation made it possible to correctly predict the positive phase of the geomagnetic disturbance on August 8 (G1), which manifested itself in improved conditions for ionosphericÿ propagation of short waves.ÿ Particles from the solar flare on August 5 and the intensification of the solar wind from the coronal hole contributed to the disturbance.ÿ This was followed by a negative phase of the disturbance (G2), during which propagation conditions deteriorated significantly.ÿ This was followed by only slightly turbulent development.

The development after August 15 should be calmer, as there are currently no major active areas near the emerging coronal hole in the northeast of the solar disk.

The Predicted Planetary A Index for August 16 to 22 is 5, 5, 15, 25, 15, 8, and 12, with a mean of 12.1.ÿ Predicted Planetary K Index is 2, 2, 5, 5, 5, 3, and 4, with a mean of 3.7.ÿ 10.7 centimeter flux is 145, 150, 145, 145, 145, 140, and 145, with a mean of 145.

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 "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt[5]


[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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þ Synchronet þ Whiskey Lover's Amateur Radio BBS

08/22/2025

On August 22, Spaceweather.com[1] reports a fast-moving Coronal Mass
Ejection, or CME, left the Sun on August 21.ÿ However, it is not Earth-directed, and is predicted to strike the planet Mars.

Solar activity has decreased back to low levels with a few weak
C-class flares observed from areas located in the northeast quadrant
of the solar disk. There are currently three sunspot regions on the
solar disk with the largest being Region AR4187. This region showed
some weak leader spot growth. The remaining two regions were quiet
and stable.
ÿ
Solar wind parameters reflected negative polarity coronal hole high
speed stream (CH HSS) influences. A disturbed solar wind environment
is likely to continue through August 22.

There is a slight chance for R1 (Minor) radio blackouts through
August 23 due to the anticipated return of old active regions.
Probabilities increase slightly to a chance for an isolated event,
most likely from the east limb, on August 24 as old active regions
return to view.

Active conditions are likely again on August 28 due to negative
polarity Coronal Hole High Speed Stream influences. Periods of G1 to
G2 (Minor-Moderate) storming are likely on September 5, with active
conditions likely on September 4 and 6, due to positive polarity
Coronal Hole High Speed Stream influences. The remainder of the
period is expected to be at quiet or quiet to unsettled levels.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, August 21, 2025, by F. K. Janda, OK1HH:

"Higher solar activity in the first half of August was caused mainly
by two sunspot groups (out of a total of 11-13), whose magnetic
configuration allowed for the occurrence of moderately powerful
eruptions (class M). After their disappearance, the number of groups
dropped to three to five, while only energetically insignificant
eruptions sporadically occurred. Changes in the speed of the solar
wind and the concentration of particles in it had a significant
impact on the Earth's ionosphere. As usual, the source on the Sun
was the boundaries of coronal holes.

"After a brief calm in the geomagnetic field from August 13 to 15,
turbulent developments followed from August 19. At the beginning,
the speed of the solar wind rapidly increased from 350 to 650 km/s,
which was accompanied by a change in the polarity of the
longitudinal component of the interplanetary magnetic field Bz to
positive in a relatively long interval from 1130 to 1630 UT.
Therefore, the deterioration of shortwave propagation conditions was
only slight, while the MUF decline was delayed. We are now likely to
see a series of relatively calm days, probably until August 27.

Major disturbances are not expected to occur until around September
5, when the Earth will enter the same stream of solar particles as
it did around August 9."

The latest video from Dr. Tamitha Skov, WX6SWW, can be found on
YouTube at, https://www.youtube.com/watch?v=brxIxVgiH_A[2] .

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[3] and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals[4]. For
an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[5] . Information and
tutorials on propagation can be found at, http://k9la.us/[6] .

Also, check this:

https://bit.ly/3Rc8Njt[7]

"Understanding Solar Indices" from September 2002 QST.

The Predicted Planetary A Index for August 23 to 29 is 5, 5, 8, 8,
10, 12, and 8, with a mean of 8.ÿ Predicted Planetary K Index is 2,
2, 3, 3, 3, 4, and 3, with a mean of 2.9.ÿ 10.7 centimeter flux is
120, 125, 120, 120, 125, 125, and 130, with a mean of 123.6.

ÿ


[1] http://Spaceweather.com
[2] https://www.youtube.com/watch?v=brxIxVgiH_A
[3] http://www.arrl.org/propagation
[4] http://arrl.org/propagation-of-rf-signals
[5] http://arrl.org/the-sun-the-earth-the-ionosphere
[6] http://k9la.us/
[7] https://bit.ly/3Rc8Njt

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þ Synchronet þ Whiskey Lover's Amateur Radio BBS

08/29/2025

Solar activity was at low levels on 18, 20, and 21 August with only C-class flares observed.ÿ Activity increased to moderate levels on 19 August following an M1.1 flare at 19/0439 UTC from an area beyond the Eastern limb.ÿ Moderate levels were also observed on 22 August as Region 4191 produced a long-duration M1.7/Sf flare.ÿ Associated with this flare was a Type II radio sweep with an estimated shock speed of 521 km/s.ÿ The associated CME was deemed to be behind the Sun-Earth line.

Moderate levels continued into 23 and 24 August with an M1.9 and an M1.3 flare, both originating from beyond the NE limb.ÿ While multiple CMEs were observed in coronagraph imagery over the period, nearly all were at or beyond the Eastern limb and none were considered to have an Earth-directed component.

Geomagnetic field activity was at quiet to unsettled levels on 18 and 24 August, bookending a negative polarity coronal hole high speed stream. Unsettled to active conditions were observed on 20-23 August as CH HSS activity elevated, with active to minor storm levels observed on 19 August.

Solar activity is expected to be at low levels, with varying chances for M-class flares (Minor-Moderate events) through 20 September.

Geomagnetic field activity is expected to be at mostly quiet levels on 29 August-3 September and again on 11-14 September.ÿ Unsettled levels are likely on 25-28 August, 7-10 September, and 17-20 September.ÿ Active conditions are likely on 4-9 September and 15-16 September, with possible minor storming on 4-6 September and 15 September.ÿ All increased activity levels are associated with coronal hole high speed stream influence.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for August 28, 2025 by F. K. Janda, OK1HH:

Given the significant decline in solar activity this spring, I expected it to increase by the end of summer at the earliest, and more likely by the beginning of fall.ÿ This expectation is now beginning to be fulfilled.ÿ And if the rise in solar activity continues, we can guess whether solar activity will continue to grow until the possible second maximum of the 25th solar cycle, let's say this fall.

A few days ago, sunspot groups began to appear in the eastern part of the solar disk, which we knew about thanks to helioseismological observations.ÿ And not only thanks to them, coronal plasma ejections extending beyond the eastern limb of the solar disk were also observable, and in recent days, an increase in the concentration of protons in the solar wind has also affected the Earth.ÿ The conditions for shortwave propagation have improved significantly due to increased solar radiation and have fluctuated significantly and rapidly, especially during the occurrence of sporadic E layers.ÿ Active regions on the Sun will pass through the central meridian in a few days.ÿ Their activity will therefore begin to have a much greater impact on the Earth's magnetosphere and ionosphere.ÿ More than a few surprises are expected.

The latest report from Dr. Tamitha Skov, WX6SWW, can be found at https://www.youtube.com/watch?v=1mVzIvfHNtc[1] .

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[2] and the ARRL Technical Information Service web page at, http://arrl.org/propagation-of-rf-signals[3] . For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[4] . Information and tutorials on propagation can be found at, http://k9la.us/[5] .

Also, check "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt[6]

The Predicted Planetary A Index for August 30 to September 5 is 5, 5, 5, 5, 5, 20, and 35, with a mean of 11.4.ÿ Predicted Planetary K Index is 2, 2, 2, 2, 2, 5, and 6, with a mean of 3.0.ÿ 10.7 centimeter flux is 158, 158, 155, 155, 145, 145, and 140, with a mean of 150.8.


[1] https://www.youtube.com/watch?v=1mVzIvfHNtc
[2] http://www.arrl.org/propagation
[3] http://arrl.org/propagation-of-rf-signals
[4] http://arrl.org/the-sun-the-earth-the-ionosphere
[5] http://k9la.us/
[6] https://bit.ly/3Rc8Njt

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þ Synchronet þ Whiskey Lover's Amateur Radio BBS

09/05/2025

Spaceweather.com[1] for September 5 reports that a total lunar eclipse
occurs on September 7th.ÿ However, it will not be visible in the
Americas.

Solar activity will likely continue at moderate levels with isolated
M-class flares through September 6 due to the combined flare
potential of Regions AR4197 and AR4207. Probabilities decrease to
just a chance for M-class flares on September 7 as AR4197 moves
beyond the western limb.

An enhanced solar wind regime is anticipated to continue into
September 6 due to a positive polarity coronal hole high speed
stream.

On September 7, High Speed Stream activity combined with the arrival
of the September 4th CME is likely to cause further G1 (Minor)
storming levels with a chance for G2 (Moderate).

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, September 4, 2025, by F. K. Janda, OK1HH:

"As soon as we begin to think that we are starting to understand
what is happening on the Sun and in its vicinity (where we and Earth
are located), Mother Nature shows us that it is not that simple. A
small example: while we were observing the extensive active region
4197 on the Sun, an eruption occurred in another, much smaller and
less conspicuous region, AR4199, which had a key influence on the
events of the following days. It happened on the evening of
Saturday, August 30, very close to the solar equator and the central
meridian, so it was directed towards Earth.

"The forecasts of further developments from all forecasting centers
were identical: the CME would arrive at Earth on September 1 in the
late afternoon to evening hours and cause a G2-class magnetic storm, accompanied by auroras. And so, it happened.

"As predicted, the geomagnetic disturbance continued on September 2.
This was followed by a relatively rapid calm, and by September 4,
the state of the Earth's magnetosphere and ionosphere began to
approach what we are used to at the end of summer and beginning of
autumn - in other words, there was a noticeable improvement in the
conditions for ionospheric shortwave propagation.

"In further developments, the Earth will be affected by another
surge of solar wind on September 6. But this should come as no
surprise, as it is a regularly recurring passage of the Earth
through a stream of intensified solar wind linked to active areas on
the Sun. The entire system, together with the Sun, rotates once
every approximately 27 days. Therefore, predictions of the onset of disturbances are relatively reliable."

The latest report from Dr. Tamitha Skov, WX6SWW, can be found at: https://www.youtube.com/watch?v=XxbAzht2Eq0[2] .

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[3] and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals[4]. For
an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[5] . Information and
tutorials on propagation can be found at, http://k9la.us/[6] .

Also, check this:

https://bit.ly/3Rc8Njt[7]

"Understanding Solar Indices" from September 2002 QST.

The predicted Planetary A Index for September 6 to 12 is 8, 12, 12,
12, 10, 5, and 5, with a mean of 9.1ÿ The predicted Planetary K
Index is 3, 4, 4, 4, 4, 2, and 2, with a mean of 3.3.ÿ 10.7
centimeter flux is 175, 160, 140, 130, 125, 125, and 120, with a
mean of 139.3.

ÿ


[1] http://Spaceweather.com
[2] https://www.youtube.com/watch?v=XxbAzht2Eq0
[3] http://www.arrl.org/propagation
[4] http://arrl.org/propagation-of-rf-signals
[5] http://arrl.org/the-sun-the-earth-the-ionosphere
[6] http://k9la.us/
[7] https://bit.ly/3Rc8Njt

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þ Synchronet þ Whiskey Lover's Amateur Radio BBS