Tad Cook, K7RA, Seattle, reports: Solar Cycle 25 activity continues this week, with no spotless days since May 6. The average daily sunspot number rose modestly this week from 24.9 to 28 while the average daily solar flux held steady at 77.8.

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

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

Here’s the geomagnetic activity forecast for June 4 – 29 from J.K. Janda, OK1HH.

The 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 a CME on May 22. Therefore, it could not be predicted in forecast issued on May 20.

Remarks:

-Parenthesis means lower probability of activity enhancement.

-Accuracy of the forecast remains lower.

From the Madison DX Club, program for Tuesday, June 8:

“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 6 meters will be discussed. Finally, references for more 6-meter info will be listed. Carl will be available to answer your questions.

Zoom host and Program Chairman, Kevin Shea, N9JKP, will be online from 5:45 CDT. Join the Zoom meeting and program with the password 124658.

Oleh, KD7WPJ/UR5BCP, wrote to say that UX0ZAB, mentioned in last week’s bulletin, is indeed a Ukraine call sign.

Ten-meter activity is starting to pick up. This website promotes 10 meters.

Here is an interesting article on solar cycle prediction.

Space Weather Woman Tamitha Skov, WX6SWW, reports the first radiation storm of Solar Cycle 25 in her latest YouTube presentation.

Sunspot numbers for May 27 – June 2 were 34, 28, 26, 27, 31, 20, and 30, with a mean of 28. The 10.7-centimeter 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.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out K9LA’s Propagation Page.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Instructions for starting or ending email distribution of ARRL bulletins are on the ARRL website.

Share your reports and observations.