Solar activity was down again this week. The sunspot number on Sunday, August 14 went all the way to 0 for the first time since January 27, which was 29 weeks ago. The average daily sunspot numbers declined nearly 50 points, to 25.6, while the average daily solar flux was down nearly 16 points to 88.5. Sunspot numbers for August 11-17 were 36, 25, 35, 0, 13, 26 and 44, with a mean of 25.6. The 10.7 cm flux was 84.2, 83.4, 83.1, 88.1, 90.4, 93 and 97.5, with a mean of 88.5. The estimated planetary A indices were 6, 5, 5, 9, 13, 8 and 6, with a mean of 7.4. The estimated mid-latitude A indices were 3, 3, 4, 8, 9, 6 and 6, with a mean of 5.6.

The latest prediction from NOAA/USAF on August 18 has the solar flux at 98 on August 19, 100 on August 20-22, 105 on August 23-25, then 110 and 115, on August 26-27, and back to 110 on August 28-31. Solar flux is expected to bottom out at 90 on September 8-12. The predicted planetary A index is 5 on August 19-20, 8 and 12 on August 21-22, 5 on August 23-25, 10, 10 and 8 on August 26-28, and 5 again on August 29-September 2. Geophysical Institute Prague predicts quiet conditions on August 19-20, unsettled August 21, quiet to unsettled August 22-24 and quiet again on August 25.

Thanks to Max White, M0VNG, of Worcester, England for sending along this story from NASA, “Solar Flares: What does it take to be X-class?” Max and several other readers, including Douglas Schauer, sent in some articles about using helioseismology to predict the appearance of sunspots. See here, here, here, here and here. One of the best articles on this subject is from astronomer Phil Plait’s blog. Also, don’t miss this video about coronal mass ejections tracked by STEREO craft, posted by Tomas Hood, NW7US.

Brad Miskimen, N5LUL, of Amarillo, Texas, was in the Ten-Ten International QSO Party (a 10 meter phone contest) on the evening of August 5, working stations in Florida, Georgia, Tennessee, Delaware and North Caroline, most S9, and some as much as 40 dB over S9, when suddenly at 0244, “the door slammed shut. I have never seen or heard everyone disappear within 10 seconds. But that’s what I experienced. Total silence!”

If we check here, we see that geomagnetic indices show a great deal of activity right around that time, with the planetary K index reaching 8, just 1 point below the maximum K index, which is 9. Checking here for that day and the next (use the archives feature in the upper right) shows that a CME strike on August 5 “sparked one of the strongest geomagnetic storms in years.”

Dan Soderlund, KB0EO, of Northfield, Minnesota wrote: “I was operating off and on all day Saturday, August 13 on 17 meters. Late in the afternoon (around 2200), I had my antenna pointed toward Europe and was working hams in Western Europe. All of a sudden, I started getting Japanese stations calling off the back of the antenna. I turned the antenna toward Japan and made about 40 QSOs with Japan -- all stations at least S6, and most were S9 plus. This lasted for about an hour and then the propagation just vanished. The interesting thing was propagation was equally good to Europe and Japan simultaneously, covering two-thirds of the Earth for an hour.”

Of course, propagation varies seasonally, even a small amount from day to day and week to week, but it looks like having propagation to Europe and Asia from Dan’s location is not uncommon. I averaged the sunspot number for August 11-13 (32), and ran W6ELprop from Dan’s location (44.45 N. 93.3 W) to Japan and it shows good signals on 17 meters from 2030-0230. When I do the same for England, it shows about 10 dB louder than Japan, but a rating showing less chance of propagation over that path. It shows a very good path from 1630-2030, but after that it changes to a C rating, which means 25-50 percent chance, instead of 50-75 percent, which is what it shows to Japan. Germany and the Czech Republic don’t look as good during that period. It seems that propagation would be best from Western Europe, and the further west, the better.

Pat Hamel, W5THT, of Long Beach, Mississippi, is active with an experimental license on 500 KHz. He says that signals from Mississippi and Louisiana were copied in Alaska around 2011 on August 12 by Laurence Howell, KL7UK, near Wasilla. Read more about the 600 meter project at here.

If you will be in or near Estes Park, Colorado on the evening of Thursday, August 25, you can attend a lecture on sunspots and solar cycles at a meeting of the Estes Valley Astronomical Society.

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.