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ARRL Propagation Bulletin ARLP027 (2020)

ARLP027 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 27  ARLP027
From Tad Cook, K7RA
Seattle, WA  July 7, 2020
To all radio amateurs 

ARLP027 Propagation de K7RA

No sunspots this week. The pattern persists, and this surprises me.
But reported a couple of weak, barely emerging
spots, never numbered, and by their magnetic polarity were from new
Solar Cycle 25.

We rely on NOAA for official sunspot numbers, and the most recent
one reported was 11 on June 15. See,

Average daily solar flux over the recent reporting week (June 25 to
July 1) averaged 68.6 up from 67.7 over the previous seven days.
Average daily planetary A index was 4.7, the same as the average
middle latitude A index.

Predicted solar flux over the next 45 days is 68, every day July 3
to August 16, which is hardly a promising outlook. Even with no
sunspots, it would be nice to see solar flux values north of 70.

Predicted planetary A index is 5 on July 3-26, 8 on July 27-28, 5 on
July 29 through August 1, 8 on August 2-3, and 5 on August 4-16.

Geomagnetic activity forecast for the period July 3-29, 2020 from

"Geomagnetic field will be,
quiet on: July 3, 9-11, 14, 18-22.
quiet to unsettled on: July 4, 8, 12-13, (15, 17,) 25-28.
quiet to active on: (July 5-7, 16, 23-24, 29).
unsettled to active on: None!
active to disturbed: None!

"Solar wind will intensify on: July (4,) 5-8, (9-10, 16-18, 21-22,)
23-25, (26-27).

- Parenthesis means lower probability of activity enhancement.
- The predictability of changes remains in the long run lower as
there are very few indications.

"F. K. Janda, OK1HH."

This video is quite dramatic and remarkable. An entire decade of
continuous solar rotation images compressed into an hour:


Mike, KA3JAW reported from Easton, PA urging everyone to monitor
29.6 MHz FM. He heard nothing on 10 meter FM over Field Day weekend.
I will start doing this myself now with a new radio that covers that

Interesting article about solar plasma flow can be found on:

Thanks to AA2F for catching errors in the A index averages appearing
in the ARRL Letter (my fault), so I could correct them in this

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see and the ARRL Technical Information
Service web page at, For an
explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good
information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for June 25 through July 1, 2020 were 0, 0, 0, 0, 0,
0, and 0, with a mean of 0. 10.7 cm flux was 68.9, 67.8, 68.9, 69.2,
68.7, 68.1, and 68.9, with a mean of 68.6. Estimated planetary A
indices were 3, 6, 7, 4, 3, 4, and 6, with a mean of 4.7. Middle
latitude A index was 2, 6, 6, 4, 4, 5, and 6, with a mean of 4.7.


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