06/27/2025

Solar activity has been at low levels for the past 48 hours, with
low-level C-class flares.
ÿ
There was a narrow coronal mass ejection (CME), likely associated
with minor flaring from Regions AR4117 and AR4118 between 1439 UTC
and 1524 UTC on June 24. Initial modeling indicated a miss, south
and behind Earth's orbit. However, it should be noted that analysis
of this event is low confidence given the assumed source location.
ÿ
An enhanced solar wind environment is expected to continue through
June 28 under a negative polarity Coronal Hole High-Speed Stream
regime before beginning to trend towards a more nominal environment
on 29 June.

There is a chance for R1-R2 (Minor-Moderate) events through June 29.
There is also a slight chance for an R3 (Strong) or greater event
through June 29, as well as a slight chance for S1 (Minor) solar
radiation storm conditions through the reporting period.

Geomagnetic field activity is likely to reach active levels on July
1 to 3, 05 and 6, and 11 and 12, all due to recurrent CH HSS
influences. Quiet, and quiet to unsettled conditions are expected to
prevail throughout the remainder of the period through July 19.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - June 26, 2025, by F. K. Janda, OK1HH:

"The last significant solar flare was recorded on June 15, reaching
an X-ray brightness of M8.4, while ejecting a CME into space. The
particle cloud arrived at Earth on June 18, with the subsequent
increase in solar wind speed, which caused an improvement in
propagation conditions in the lower shortwave bands.

"Although eruptions with higher X-ray brightness were also recorded,
they only caused shorter attenuation in the lower layers of the
ionosphere on the illuminated part of the Earth.

"Overall solar activity declined steadily after June 15, with five
to six visible sunspot groups. At most two were capable of producing
larger eruptions.ÿ Their proximity to two of the three observable
coronal holes near the equator made it possible to predict an
intensification of the solar wind and the occurrence of geomagnetic disturbances for June 25-26 (or possibly also June 27).

"This was all the more likely given that it was the central meridian
region. Since then, however, the sunspot groups and coronal holes
have shrunk. The increase in solar wind speed (up to 700 km/s) and
geomagnetic activity (only G1) was therefore smaller. However, the
flux of electrons with energies above 2 MeV reached high values,
with a maximum flux of 1,260 pfu at 25/1355 UTC.

"Unfortunately, an increase in the concentration of free electrons
in the Earth's ionosphere is a relatively common phenomenon this
year and worsens the conditions for shortwave propagation.

"A return to background levels is expected from June 28. In July,
larger sunspot groups will return to the solar disk. Therefore, the
solar flux will rise slightly during the first ten days. Only a very
slight improvement in shortwave propagation conditions can be
expected in the summer ionosphere of the Earth's northern
hemisphere."

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.

The Predicted Planetary A Index for June 28 to July 4 is 15, 10, 5,
15, 15, 12, and 5, with a mean of 11.ÿ Predicted Planetary K Index
is 3,3, 2, 4, 4, 4, and 2, with a mean of 3.1.ÿ 10.7 centimeter flux
is 140, 145, 145, 140, 140, 140, and 145, with a mean of 142.1.

ÿ


[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

07/11/2025

Spaceweather.com reports solar activity was at low levels with only C-class flares observed.ÿ The largest flare during the period was a C8.9 from an unnumbered region beyond the east limb at S13.ÿ This region was also responsible for the majority of the remaining flares alongside Regions 4136 and 4137.

An approximate M2 was observed by Solar Orbiter at 10/1326 UTC just beyond the east limb, brightening can be seen in the SUVI-94 channel at this time.ÿ A slow moving CME was observed in coronagraph imagery, modelled and was determined to not have any impact.

Solar activity is expected to be low with a chance for M-class flares, minor to moderate, through 13 July, primarily due to the flare potential of Region 4136.

Solar wind parameters remained at nominal conditions.ÿ Total field was 2-5 nT with the Bz component between +/-4 nT.ÿ Solar wind speeds were between 350-400 km/s.ÿ The phi angle was variable after 10/0500 UTC.

Nominal solar wind conditions are expected through 11 July.ÿ The co-rotating interacting region associated with a positive polarity CH HSS is expected to arrive 12 July, an enhancement of the solar wind parameters will follow the arrival and remain enhanced thereafter.

Mostly quiet conditions are expected 11 July.ÿ Unsettled to active conditions are likely starting 12 July as Earth moves into a geoeffective position with a positive polarity CH HSS.

There is a decreased chance for minor to moderate radio blackouts on 11 July with most regions on the visible disk rotating off and no appreciable spot groups rotating on.ÿ Conditions could increase on 12 or 13 July as old Regions 4117, 4118, 4120, and 4121 rotate back onto the visible disk.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere July 6 and 10, 2025

Although solar activity is lower this year than it was last year, it is still at the maximum level of the eleven-year cycle.ÿ Moreover, it is quite possible that it will increase further this year.ÿ This is indicated by the continuing slight predominance of activity in the northern half of the solar disk, while in the southern half we more often observe relatively large coronal holes.ÿ The active regions are mostly simple (magnetic type alpha or beta) and therefore, with a few exceptions, do not show significant eruptive activity.

Although solar flares have not been powerful recently, they are quite often accompanied by CMEs.ÿ When ejected particles hit Earth, it is often three to four days after the CME is observed, instead of the usual two to three days. This is one reason why the error in predicting the arrival time of the particle cloud is slightly increasing.ÿ This is especially true when their source is on the far side of the Sun.

The solar wind has finally slowed down in recent days (from speeds of over 800 km/s observed not long ago to less than 400 km/s now) and the interstellar magnetic field has weakened, which has finally had a positive effect on the state of the Earth's ionosphere, as well as the shortwave propagation conditions.ÿ Although the arrival of a high-speed stream from a recurring coronal hole with negative polarity can be expected from July 4, causing unstable geomagnetic conditions, the phenomenon should not last long.ÿ In addition, the low flux of electrons with energies greater than 2 MeV is likely to remain, so a return to fairly favorable conditions can be expected.

In connection with the occurrence of a large coronal hole in the southeastern part of the solar disk, slightly increased geomagnetic activity can be expected.ÿ In the coming days (starting July 13-14), it may reach level G1.

On the above-mentioned days (July 13 to 14, or 1 to 2 days later), the negative impact on the ionosphere could be intensified by declining solar activity. Further developments cannot be predicted with greater accuracy, but the probability of disturbances will be higher in the last third of July.

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] ÿFor 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.

The Predicted Planetary A Index for July 12 to 18 is 10, 8, 8, 12, 12, 10, and 10, with a mean of 10.ÿ Predicted Planetary K Index is 4, 3, 3, 4, 4, 4, and 4, with a mean of 3.7.ÿ 10.7 centimeter flux is 105, 105, 110, 115, 120, 125, and 125, with a mean of 115.


[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

07/25/2025

Solar activity was at low levels.ÿ The largest flare was a C7.6 from Region 4136.ÿ C-class activity was also observed from several other regions during the highlight period.ÿ No Earth-directed CME activity was observed.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at high levels on 14-20 July in response to persistent positive polarity CH HSS influence.

Geomagnetic field activity reached Minor storm levels on 14, 15, and 17 July due to positive polarity CH HSS influence.ÿ Solar wind speeds were elevated to as high as 700 km/s on 15 and 17 July.ÿ The remaining days were at quiet to active levels despite enhanced solar wind parameters.

Forecast of Solar and Geomagnetic Activity 21 July-16 August 2025

Solar activity is expected to be at mostly low levels with a chance for M-class, Minor to Moderate, flares for the outlook period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels on 21-22 July, 24-30 July, 5-6 August, and 10-16 August all due to recurrent CH HSS influences.ÿ Low to moderate levels are expected on the remaining days.

Geomagnetic field activity is expected to be at active to Minor storm levels on 23 July, 1-4 August and, 7-14 August due to recurrent CH HSS effects.ÿ Quiet to unsettled levels are expected on the remaining days of the outlook period.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for July 24, 2025 by F. K. Janda, OK1HH:

Less than a year has passed since the probable peak of the 25th eleven-year cycle, which means that we are still in a period of high solar activity.ÿ This does not necessarily mean that there must be a high sunspot number, many eruptions, or a high level of solar radio noise power flux (or solar flux for short).ÿ Currently, there is mainly the high speed of the solar wind that alternately causes high concentrations of negatively charged free electrons in the ionosphere, which quickly recombine with positively charged protons. The result is irregular changes in shortwave propagation conditions, accentuated in the summer by the activity of the sporadic E layer.

From mid-July, sunspot activity initially increased, then declined significantly in the last third of the month as a result of the setting of larger sunspot groups.ÿ No major eruptions were observed in the setting groups. Therefore, the Earth's magnetic field calmed down, especially on July 20-21. The geomagnetic disturbance on July 23 was expected, as the Earth entered the co-rotating interaction region (CIR), where it was hit by solar wind and triggered a G1-class geomagnetic storm (CIRs are transition zones between fast and slow solar wind streams and contain shock waves and amplified magnetic fields similar to those in CMEs).

Forecasts of further developments from various sources now differ considerably. If we look at the part of the far side of the Sun that is currently hidden behind the eastern limb of the solar disk, we can first expect the current level of solar activity and, at the beginning of August, a slight decrease, accompanied by a slight increase in geomagnetic activity.

The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found on YouTube at:ÿ

https://www.youtube.com/watch?v=n1N58cOnedo[1]

The Predicted Planetary A Index for July 26 to August 1 is 5, 5, 5, 5, 5, 5, and 15, with a mean of 6.4.ÿ Predicted Planetary K Index is 2, 2, 2, 2, 2, 2, and 4, with a mean of 2.3.ÿ 10.7 centimeter flux is 135, 135, 130, 130, 130, 130, and 130, with a mean of 131.4.

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]


[1] https://www.youtube.com/watch?v=n1N58cOnedo
[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

08/01/2025

Spaceweather.com reports solar activity was at low levels with only minor C-class flares observed.ÿ Region 4154 produced a C1.4 flare on 31 July.ÿ Region 4153 contributed the majority of the flares, including a C1.3 flare, a C1.5/Sf flare, and a C1.6 flare on 31 July.ÿ Both of these regions remained mostly unchanged during the period.ÿ Region 4166 exhibited growth during the period yet remained mostly inactive.ÿ Newly numbered Region 4167 exhibited growth during the period and produced a C1.9/Sf flare.ÿ The remaining regions were stable or in decay.

Solar activity is expected to be low with a chance for M-class flares, Minor-Moderate, through 03 August.

Solar wind parameters are expected to continue a waning trend on 01 August as the negative polarity CH HSS moves from its geoeffective location.ÿ An additional disturbance cannot be ruled out for 02 August due to the 30 July CME event mentioned in the previous discussion.ÿ Aside from the possible CME influence, conditions are expected to remain at mostly background levels through 03 August.

Quiet conditions, with isolated unsettled periods, are expected to prevail on 01 August as CH HSS effects gradually wane.ÿ Quiet to unsettled levels are expected on 02 to 03 August, with a slight chance for an isolated active period on 02 August, due to the possible July CME passage.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for July 31, 2025 by F. K. Janda, OK1HH:

We are most likely still in the period of the maximum of 11-year solar activity cycle No. 25.ÿ Its peak was preliminarily recorded in the fall of 2024, but this year's course was very unusual, while its response in the ionosphere was unexpected, especially in May and June.ÿ Solar activity should continue to decline slowly this year, with a more rapid decline expected starting in 2026. Therefore, there is still hope for favorable shortwave propagation conditions this fall, especially in the shorter part of the range (say, at frequencies above 20 MHz).

Last week, only relatively small sunspot groups were observed on the Sun, with no major flares.ÿ This was accompanied by smaller fluctuations in the speed of the solar wind and, therefore, a calmer geomagnetic field.ÿ Although the summer season in the northern hemisphere of the Earth is not favorable for long-distance shortwave propagation, it was still an improvement over previous months.

There should be fewer sunspot groups on the far side of the Sun. But it seems that those that will soon appear will be larger than those we are currently observing.

Solar ultraviolet and X-ray radiation, together with the solar wind, are the main causes of changes in the Earth's ionosphere, but they are not the only ones.ÿ The ionosphere also reacts to processes taking place below it.ÿ These include gravitational waves (formed at the interface between air masses of different densities, for example in meteorological fronts) and infrasound caused by earthquakes and typhoons.ÿ Scientific research into these phenomena is still in its infancy, and although records of changes in the ionosphere following the earthquake on the east coast of Kamchatka (M8.8, Tue 29 July 2025, 23:24:51 UTC) are available, for DX signal hunters this is still more of a curiosity.

The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found on YouTube at:

https://www.youtube.com/watch?v=-XM4kZ-vvRk[1]

The Predicted Planetary A Index for August 2 to 8 is 5, 5, 12, 8, 5, 20, and 15, with a mean of 10.ÿ Predicted Planetary K Index is 2, 2, 4, 3, 2, 5, and 4, with a mean of 3.1.ÿ 10.7 centimeter flux is 140, 150, 155, 155, 155, 155, and 160, with a mean of 152.9.

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[2] ÿand 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]ÿ


[1] https://www.youtube.com/watch?v=-XM4kZ-vvRk
[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