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ARLP033 follows
ARLP033 follows
ZCZC AP33
QST de W1AW
Propagation Forecast Bulletin 33 ARLP033
From ARRL Headquarters
Newington, CT August 14, 2026
To all radio amateurs
SB PROP ARL ARLP033
ARLP033 The ARRL Solar Report
Weekly Highlights and Forecast, August 17, 2026, by NOAA Space Weather Prediction Center:
Solar activity ranged from very low to low levels throughout the period.
No R1 (Minor) or greater events were observed.
The largest flare was a C8.2/Sn at 16/1928 UTC from Region 4506. An associated CME was observed in LASCO C2 imagery following the C8.2 flare, but analysis is ongoing in order to determine any Earth-directed component. Other activity included the lift-off of av large filament near S16E22 at 14/0332 UTC which produced a CME that is expected to arrive on 17-18 Aug.
Geomagnetic field activity is expected to reach active levels on 17-18 Aug due to the anticipated arrival of a CME that left the Sun on 14 Aug. Active conditions are expected again on 21-22 Aug and 04 Sep due to the influences of a CH HSS.
Quiet and quiet to unsettled conditions are expected to prevail throughout the remainder of the outlook period.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, August 13, 2026, by F. K. Janda, OK1HH:
It appears that solar activity will remain relatively low for a few more days before mid-August; however, it is more likely that July s surprise will repeat itself and solar activity will increase after a few days.
This would be a more favorable scenario for possible future developments in the Earth s ionosphere.
Although the sporadic E layer often plays a significant role in the ionosphere at mid-latitudes, its season will gradually come to an end.
Solar activity will rise in the second half of the month, while geomagnetic activity is expected to decrease on average.
It is hard to imagine a better scenario for future developments, and it appears that this one will at least partially come to pass.
The Predicted Planetary A Index for August 14 to August 20 is 5, 5, 5, 15, 12, 20, and 8 with a mean of 10. The Predicted Planetary K Index is 2, 2, 2, 4, 4, 5, and 3 with a mean of 3.1. Predicted 10.7 centimeter flux is 95, 95, 95, 100, 105, 105, and 105 with a mean of 100.
For more information concerning shortwave radio propagation, see www.arrl.org/propagation
and the ARRL Technical Information Service web page at www.arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere. Information and tutorials on propagation can be found at http://k9la.us.
Also, check this: "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt
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