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