SB PROP @ ARL $ARLP032
ARLP032 The ARRL Solar Report

ZCZC AP32
QST de W1AW
Propagation Forecast Bulletin 32 ARLP032

From ARRL Headquarters

Newington CT August 29, 2025
To all radio amateurs

SB PROP ARL ARLP032
ARLP032 The ARRL Solar Report

Solar activity was at low levels on 18, 20, and 21 August with only C-class flares observed. Activity increased to moderate levels on 19 August following an M1.1 flare at 19/0439 UTC from an area beyond the Eastern limb. Moderate levels were also observed on 22 August as Region 4191 produced a
long-duration M1.7/Sf flare. Associated with this flare was a Type II radio sweep with an estimated shock speed of 521 km/s. 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. 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. Unsettled levels are likely
on 25-28 August, 7-10 September, and 17-20 September. Active conditions are likely on 4-9 September and 15-16 September, with possible minor storming on 4-6 September and 15 September. 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. This expectation is now beginning to be fulfilled. 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.

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.

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.


Active regions on the Sun will pass through the central meridian in a few
days. Their activity will therefore begin to have a much greater impact on
the Earth's magnetosphere and ionosphere. 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 [ https://www.youtube.com/watch?v=1mVzIvfHNtc ] .


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


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


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. Predicted Planetary K Index is 2, 2, 2,
2, 2, 5, and 6, with a mean of 3.0. 10.7 centimeter flux is 158, 158, 155,
155, 145, 145, and 140, with a mean of 150.8.

NNNN
/EX

ARRL The National Association for Amateur Radio(R)
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SB PROP @ ARL $ARLP032

ARLP032 Propagation Forecast

ZCZC AP32
QST de W1AW
Propagation Forecast Bulletin 32 ARLP032

From ARRL Headquarters

Newington, CT August 7, 2026
To all radio amateurs

SB PROP ARL ARLP032
ARLP032 The ARRL Solar Report

Solar activity has been at low levels, with occasional B-class flaring and isolated low-level C-class flares observed. The largest event of the period
was a C1.6/Sf flare on August 5 from Region 4502.


The six numbered sunspot regions on the visible disk are mostly stable or in varying stages of decay. Region 4498 showed a slight decrease in penumbral extent. Region 4499 declined in length and area, though limb foreshortening hindered complete characterization of its magnetic structure. Region 4500 weakened in its leading spot. Region 4501 lost its trailing spots, decaying into a unipolar group.


Region 4502 exhibited consolidation across both magnetic poles. Region 4503
was limited by foreshortening near the southeast limb, but appeared to show modest new flux emergence in its trailing spots to become a bipolar group.


No Earth-directed coronal mass ejections (CMEs) were observed in available coronagraph imagery.


With ongoing region decay and several active regions in the western
hemisphere expected to rotate off the disk over the coming days, there is a decreasing chance for M-class (R1-R2/minor-moderate) flares August 6. Current Solar Orbiter Helioseismic and Magnetic Imager (HMI) imagery suggests no significant returning regions during the forecast period.


Solar wind parameters remained at quiet, ambient, levels throughout the
period. Solar wind speeds reflected a slow wind regime, gradually declining from early values near 400 km/s down to approximately 345 km/s late in the period. The phi angle remained predominantly in the positive (away from the Sun) sector.


Solar wind parameters are expected to remain in a slow wind regime through early August 7. Later in the day, enhancements are anticipated to begin due
to the arrival of CMEs that departed the Sun on August 3. These CME enhancements may persist into August 8, alongside potential weak influences from a negative polarity coronal hole high-speed stream (-CH HSS) that is likely too far south to become significantly geoeffective.


Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, August 6, 2026, by F. K. Janda, OK1HH:


The effects of the expected decline in solar activity (within the context of the 27-day cycle), which began before the end of July, were exacerbated by
the geomagnetic disturbance that occurred on August 2 3. The effects of this decline will still be felt in the ionosphere during the first third of
August.

The second third of the month will bring an improvement.
Then, in the final third, when solar radiation levels will once again be elevated, the approaching fall will also have a noticeable and positive
effect on the ionosphere.


The Predicted Planetary A Index for August 7 to August 13 is 5, 5, 5, 5, 8,
8, and 5 with a mean of 5.9. The Predicted Planetary K Index is 2, 2, 2, 2,
3, 3, and 2 with a mean of 2.3. Predicted 10.7 centimeter flux is 110, 105, 105, 105, 105, 105, and 110 with a mean of 106.4.


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


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

NNNN
/EX

ARRL The National Association for Amateur Radio(R)


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