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The K7RA Solar Update


At 0005 UTC on September 15 the Australian Space Weather Forecast Centre issued a Geomagnetic Disturbance Warning.

“The previous geomagnetic warning is extended for two more days. The high-speed streams associated with the coronal hole is expected to persist for a few days. If the Bz component of the IMF turned strongly southward for prolonged periods, earth could experience minor storm conditions. Otherwise, expect mostly unsettled to active condition for the next two days (15 and 16 September).


15 Sep:  Active
16 Sep:  Active"

Over the past reporting week (September 7-13) sunspot numbers and solar flux were lower, while geomagnetic indicators were higher.

Average daily sunspot numbers declined from 87.3 to 45, and average daily solar flux went from 114.1 to 97.6.

Average daily planetary A index increased from 18 to 27.3, and average daily mid-latitude A index went from 16.7 to 18.3.

Predicted solar flux is 74 on September 15-21, then 90, 92, 95, 98, 105, 110, 115 and 120 on September 22-29, 125 on September 30 and October 1, then 120, 115, 110, 100, 95, 90, 85, 83, 81 and 84 on October 2-11, 83 on October 12-14, 84 on October 15, 85 on October 16-17, then 88, 90, 92, 95, 98, 105, 110, 115 and 120 on October 18-26, 125 on October 27-28 and 120 on October 29.

Predicted planetary A index is 28 on September 15-16, 26 on September 17, 12 on September 18-21, 5 then 5, 8, 5, 8 and 5 on September 22-26, 20 on September 27-29, then 18, 15, 12 and 8 on September 30 through October 3, 5 on October 4-7, then 7 and 12 on October 8-9, 30 on October 10-12, 20 and 10 on October 13-14, 5 on October 15-16, then 8, 5, 5, 8, 5, 8 and 5 on October 17-23, 20 on October 24-26, then and 18, 15 and 12 on October 27-29.

Geomagnetic activity forecast for the period September 15-October 11, 2017 from OK1HH.

“Geomagnetic field will be:
Quiet on September 23-24
Mostly quiet on September 20, 27
Quiet to unsettled September 19, 21-22, October 4, 6
Quiet to active on September 15, 17, 25-26, 30, October 1-3, 7-8, 10-11
Active to disturbed on September 16, 18, 28-29, October 5, 9

Amplifications of the solar wind from coronal holes are expected on September 15-19, 27-29, October (1,) 2-5, (8)

- Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction.

F.K. Janda, OK1HH
Czech Propagation Interested Group”

Here are videos from September 7 by Dr. Tamitha Skov. The second one is an hour-long program in which she answers viewer’s questions about recent activity. It contains lots of great information. I love it when she tries to set the record straight about HAARP. No, it is not a tool for mind control or messing with the weather!

Here is a Newsweek article about seven massive solar flares in seven days:


Chuck Zabriskie, KE5HPY, of Houston, Texas reported on September 9: “I thought one could add WSPR to the propagation aids discussed in your latest report. With the high flux report, I put my homebrew 10-meter WSPR receiver on-line and happily recorded TI, CE, ZL and multiple VK calls for the first time in a long while. Of course, those were regular events a couple of years ago, but now are rare enough to me get excited to look at the logs.”

On September 11 N8II, Jeff Hartley in Shepherdstown, West Virginia wrote: "While it has been mostly bad, the very high absorption has settled down at times to make for some interesting openings. I observed a total ionospheric blackout at 1703Z Sunday, followed at 2030Z with some of the best conditions in the Worked All Europe contest of the whole weekend from then until the end at 2400Z. Northern and eastern Europe were not workable, however, on either 20 or 40 meters except for Ukraine and southern Russia on 40 meters. Signals from Germany to the west and south were loud on 20 meters in the 2100Z hour. I was unable to work any Europeans at 2400Z Saturday with the very high absorption conditions at that time, despite loud French signals on 20 meters in the 2300Z hour."

On September 14 Jeff wrote: "It has been a roller coaster of conditions with some equatorial paths enhanced in the past 9 days or so. The only time I heard Asia during the AADX phone contest on Labor Day weekend was Sunday around 0100Z and that was Kazakhstan. That weekend, I primarily operated the Colorado QSO party and would say that 20 meters was poor a couple of hours in the early afternoon, but otherwise in decent shape to Colorado, which is a good distance for us for single-hop F2 despite a high K index. Forty meter signals seemed down a bit, especially early evening, but some mobiles and K8TE operating portable, probably with a vertical and barefoot, were easy copy by 2400Z (my local sunset was about 2335Z). Only W7RF who has a pretty big station was heard on 80.

“The CW Ops contest started at 2000Z on September 2 and there seemed to be some Es into the W4/5 call areas; there were many loud signals and western European stations were workable without having to move my main Yagi from the west. Later, there also seemed to be some Es into the Midwest, allowing loud signals past when F2 would normally fade.

“Tuesday, September 5, was an above-average day despite a fairly high K index. In the 1200Z hour on 20-meter SSB, I worked ZS3Y in South Africa long path, VK4FW/P who was in a park, VK6JDW, and P29LL in Papua New Guinea. Then I checked 30 meters to find VK4FW/P about 10 dB louder than he was on 20 meters, as well as E51JHQ in the South Cook Islands. At 1308Z, I tried a CQ on 15-meter SSB after hearing a strong British station on CW and F4BWX (an American living in Royan, France) answered saying I was the first USA station he had heard on 21.300 MHz during over 4 weeks of monitoring. He was a solid S5 here, despite running only 100W to a dipole. I went on to work several stations in England and Germany on 15-meter CW and phone. The biggest European surprise was a good signal from Ivan, RA7A in Krasnodar, Russia (Black Sea area). The I saw a spot from North Carolina of James, 9V1YC, in Singapore on 15-meter CW and, amazingly, he was a solid S5-6 here and I went right into his log at 1534Z. I also heard a weak Indonesian station on 17 meters around 1300Z. This was the best day of the week/past several months on 15 meters. After that the flares and high absorption limited anything non-equatorial. 

“On the 7th at 0045Z, I worked special anniversary calls XK150YT and CI1AAA operating from Whitehorse, Yukon, Canada and they were S9, but CQs toward Asia were fruitless and no spots of Asians were noted. FK8IK, in New Caledonia, had a good signal on 15-meter CW at 0051Z. He was worked in North America on 12 and 10 meters earlier.

“Since then, conditions have been poor. The Worked All Europe contest was 9th-10th and was quite a challenge. The first good opening I found on 20 meters was around 2300Z on Saturday evening, but I was gone most of the day. Spanish and French stations were loud, but no stations were loud enough to hear me on 40 meters due to disturbed conditions. Sunday morning signals were poor on 20 meters, but I did manage QSOs with northern Sweden and the Aland Islands along with other European big guns. There was a brief opening on 15-meters that allowed me to work UA7K in southern Russia at 1335Z, as well as Spain, Slovenia, Croatia, and Malta around 1445Z. There was a total blackout on all bands when I checked at 1703Z, due to the X8 class flare, but by 2000Z signals from Germany, Italy, the Balkans were normal and I was able work the same areas on 40 meters in the 2300Z hour, but activity was pretty low.”


So, in last week’s bulletin ARLP036, we reported a remarkable increase in solar activity. On the air, HF radio operators reported fantastic conditions, at least in quieter periods between solar flares. The average daily sunspot number was 87.3 reported in ARLP036. How long since we have seen similar activity?

Last year, in bulletin ARLP034 on August 19, 2016, the average sunspot number reported was 73.9, and it was 86.6 in ARLP007 on February 12, 2016. However, the last time we reported a higher average weekly sunspot number than last week’s bulletin was November 6, 2015 when it was 90.3.

Looking back further in 2015 we saw these numbers:

120.9 40  Oct 2, 2015
112.4 33  Aug 14, 2015
104.5 32  Aug 7, 2015
112.4 24  Jun 12, 2015
146.9 20  May 15, 2015
120.9 17  Apr 24, 2015

The number after the average sunspot number on the left is the propagation bulletin number for that year. Perhaps we will see a return to this level of activity in 3-4 years, after a projected minimum in 2019-2020.


For more information concerning radio propagation, see the ARRL Technical Information Service 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 September 7-13, 2017 were 94, 89, 49, 38, 23, 11, and 11, with a mean of 45. 10.7 cm flux was 12bbbb8.5, 116.8, 107.2, 100.2, 79.9, 75.5, and 75.1, with a mean of 97.6. Estimated planetary A indices were 38, 96, 6, 7, 11, 18, and 15, with a mean of 27.3. Estimated mid-latitude A indices were 23, 50, 6, 12, 8, 16, and 13, with a mean of 18.3.