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ARRL Propagation Bulletin ARLP023 (2021)

ARLP023 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7RA
Seattle, WA  June 4, 2021
To all radio amateurs 

ARLP023 Propagation de K7RA

Solar Cycle 25 activity continues this week, with no spotless days
since May 6.

Average daily sunspot number rose modestly this week from 24.9 to
28, and average daily solar flux held steady at 77.8, unchanged from
last week.

Predicted solar flux over the next month is 75 on June 4-6, 72 on
June 7-11, 78 on June 12-15, 80 on June 16-18, 78 on June 19-22,
then 76, 75 and 76 on June 23-25, 72 on June 26 through July 5, then
73,75 and 76 on July 6-8. Solar flux may rise to 80 on July 13-15.

Predicted planetary A index is 8 on June 4, 5 on June 5-15, 20 and
10 on June 16-17, 5 on June 18-27, then 8, 5, 8 and 8 on June 28
through July 1, and 5 on July 2-12.

Geomagnetic activity forecast for the period June 4-29, 2021 from

"Geomagnetic field will be:
quiet on: June 10, 12-13, 24-27
quiet to unsettled on: June 5-6, 17-20, 28-29
quiet to active on: June 4, 7-9, 11, 14-15, 21-23
unsettled to active: June 16
active to disturbed: nothing predicted

"Solar wind will intensify on: June (7,) 9, (14-19, 22, 24, 29).
"The increased geomagnetic activity on May 26-27 was caused by solar
flares with CME on May 22. Therefore, it could not be predicted in
forecast issued on May 20.

"Parenthesis means lower probability of activity enhancement.

"Accuracy of the forecast remains lower."

From Madison DX Club, program for Tuesday evening, June 8th. All are

"'Modes of Propagation on 6 Meters' will be presented by propagation
expert Carl Luetzelschwab, K9LA. Carl will begin with a brief look
at the atmosphere and the ionosphere. He will then cover atmospheric
modes (including polar mesosphere summer echoes and the Hepburn
tropo maps) and ionospheric modes (E and F2 regions and sporadic-E).
G3YLA's and K1YOW's recent work with sporadic-E, and the eBook by
K5ND on 6m will be discussed. Finally, references for more 6m info
will be listed. Carl will be available to answer your questions, so
please join us for another interesting evening on Tuesday, June 8th.
All are welcome.

"Time: Our Zoom host and Program Chairman, Kevin Shea, N9JKP, will
be online from 5:45 PM Central Daylight Time to socialize before the
business meeting begins and to provide time to work through any
technical issues. In case of problems getting on, you can call or
text Kevin at (608) 444-4125.

"A brief business meeting will begin at 6:00 PM Central Daylight
Time.  The program will begin immediately following the meeting at
6:30 PM Central Daylight Time, sharp. All interested hams are

"To Join the Zoom Meeting and Program simply use this link:


"Meeting ID: 831 8139 6616
Password: 124658"

Oleh, KD7WPJ/UR5BCP wrote:

"In the latest Propagation report you published N4SO's statement
that UX0ZAB is not a Ukraine call sign.

"It is not true.

"UX prefix belongs to Ukraine, and UX0ZAB is a Ukrainian call sign.

"You will find additional information about UX0ZAB from"

10-meter activity is starting to pick up.

Here is a web site promoting 10-meters:

Interesting article on solar cycle prediction:

Dr. Tamitha Skov, WX6SWW, reports the first radiation storm of Solar
Cycle 25:

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

For more information concerning shortwave 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

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

Sunspot numbers for May 27 through June 2, 2021 were 34, 28, 26, 27,
31, 20, and 30, with a mean of 28. 10.7 cm flux was 83.3, 77.4, 76,
74.4, 81.7, 75.2, and 76.3, with a mean of 77.8. Estimated planetary
A indices were 16, 3, 7, 6, 3, 3, and 5, with a mean of 6.1. Middle
latitude A index was 15, 3, 7, 7, 4, 3, and 5, with a mean of 6.3.


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