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The K7RA Solar Update


That was a little scary seeing the daily sunspot number at zero for four days, June 3-6, but conditions seem to have recovered nicely.

Average daily sunspot number for this reporting week (June 9-15) was 29.1, up from 7.7 the previous week. The minimum non-zero sunspot number is 11, due to the way sunspots are counted. A sunspot number of 11 does not mean there are 11 sunspots. It means there is one sunspot (counting as one point) in one sunspot group (adding 10 points). A second sunspot raises the sunspot number to 12, unless that spot is on its own and not clustered with the other spot, in which case the sunspot number would be 22. So that average daily sunspot number of 7.7 from the previous week is due to the fact that four out of the seven days had sunspot numbers of zero. The rest were 27, 12 and 15. You would never see a day with an actual sunspot number of 7.7.

Average daily solar flux this week was 88.3, up from 80.7 last week. I think the lowest solar flux number I’ve seen is 66. Solar flux is measured three times per day at 2.8 GHz in Penticton, British Columbia. The official number reported for the day is just the reading at local noon.

You can see the thrice daily solar flux reading direct from Canada at .

Predicted solar flux for the next month is pretty flat, at 88 on June 17-23, 85 on June 24-30, 80 on July 1-5, 85 on July 6-9, 92 on July 10-11, 95 on July 12-18, 92 and 90 on July 19-20, 85 on July 21-27, and 80 again after July 27.

Predicted planetary A index is 8 on June 17-18, 5 on June 19-23, then 12 and 8, on June 24-25, 10 on June 26-27, 5 on June 28 through July 1, then 25, 20 and 8 on July 2-4, 5 on July 5-6, 8 and 10 on July 7-8, 8 on July 9-10, then 5, 8, 12 and 8 on July 11-14, 5 on July 15-19, then 10, 12 and 8 on July 20-22, 1 on July 23-24, and 5 on July 25-28.

You can see this same daily 45 day forecast of solar flux and planetary A index, usually posted after 2100 UTC at .

Petr Kolman, OK1MGW, sent this geomagnetic forecast:

Geomagnetic activity forecast for the period June 17-July 13, 2016

Geomagnetic field will be:
Quiet on June 21-22
Mostly quiet on June 19-20, 29-30, July 1, 5-6
Quiet to unsettled on June 25, 28, July 4, 7, 10, 13
Quiet to active on June 17-18, 23-24, 26-27, July 8-9, 11-12
Active to disturbed on June (18), July 2-3

Amplifications of the solar wind from coronal holes are expected on June 17-18, 23-24, 26-27, July 2-3, 8-12

(Parenthesis means lower probability of activity enhancement).

In this Astrophysical Journal article, we see a study that tracks geomagnetic numbers against the interplanetary magnetic field and solar flux. Is there a correlation?

Also check this one, which I hesitate to pass on since mention of a Grand Minimum can generate so much fear and loathing:

Jon Jones, N0JK, in EM28 (Lawrence, Kansas) wrote: “June 14 was a great day for the Caribbean, Central America and northern South America from Kansas. Six meters was open from 1530z or so to after 2350z to these areas. I listened to 6Y5WJ run a bunch of Qs. I had chased Jamaica for many years on 6, then work Josh with one call at 2007z. Heard him for hours. Josh hit an honest 599.

“I logged HH2AA at 1951z, who reportedly was running just 8 W to a wire antenna. Also worked John, FS/K9EL FK88 at 2031z. As I was watching our 5 year old granddaughter, I could not go out portable, so used my dipole in the attic at 100 W. I worked ZF1EJ earlier at 1742z.

“Later, around 2300z, P43A popped in big and loud on 50.115. I worked P43K at 0038z June 15. P43A worked a bunch of stations from the Midwest to east coast up to W1. All of this was multi-hop sporadic E.

“One of the best openings to these regions via Es in years.”

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the 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



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