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The K7RA Solar Update


At 0132 UTC on July 30 the Australian Space Forecast Center issued a geomagnetic disturbance warning, saying a high speed solar wind from a recurring coronal hole is expected to raise geomagnetic activity levels to minor storms on July 31 and August 1. They predict quiet to minor storm levels on July 31 and minor storm declining to unsettled conditions on August 1.

Solar activity currently remains in the doldrums, with average daily sunspot numbers rising just 4.5 points to 47.9 during the July 23-29 period from the prior week. Average daily solar flux over the same periods rose just 1.5 points to 96.4.

When I look at the solar disc displayed at I count six numbered sunspot groups, but they are not magnetically complex, and the types of radiation we need to energize our ionosphere is weak.

The most active geomagnetic day was July 23, when the planetary A index was 23 and the mid-latitude A index was 21. That day there was a mild geomagnetic storm caused by a coronal mass ejection that did not hit earth directly.

Predicted solar flux is 105 on July 31 through August 2, 110 on August 3-5, 115 on August 6, 110 on August 7, 100 on August 8-9, 95 on August 10-13, then 90 and 85 on August 14-15, and 100 on August 16-17. Solar flux peaks at 115 on August 28-31, then drops below 100 after September 5.

Predicted planetary A index is 18 on July 31, 24 on August 1, then 16, 12 and 8 on August 2-4, then 5, 8 and 20 on August 5-7, then 15 on August 8-9, and 8 on August 10, 5 on August 11-15, 10 on August 16, 5 on August 17-18, then 15 and 10 on August 19-20, and 5 on August 21-23.

OK1MGW predicts the geomagnetic field will be active to disturbed on July 31 and August 1, quiet to active August 2, mostly quiet August 3-5, quiet to active August 6, active to disturbed August 7-8, quiet to active August 9, quiet to unsettled August 10-11, quiet August 12-14, mostly quiet August 15, quiet to unsettled August 16, mostly quiet August 17, quiet to active August 18, quiet to unsettled August 19-22, and mostly quiet August 23-26. He expects increased solar wind on July 31 through August 3, and again on August 6-9.

Rich Camp, WA7VGN, of Las Vegas, Nevada wanted to be sure meteor showers also occur during daylight. Yes, they do, and you can make contacts via meteor scatter day and night.

Jon Jones, N0JK, passed along a good resource for meteor scatter, Ping Jockey Central:

Jon mentioned this will be a great tool for checking activity during the upcoming Perseids Meteor shower, which is August 11-14 this year.

Jon also passed along some sporadic-E news:

“The summer 2015 North America Sporadic E skip season is winding down. Usually the peak period is around the summer solstice through the first week to 10 days of July.

“Some late season July Es continued. On July 21, PR8ZX GI64 in Brazil worked into the Midwest on 6 meters and was spotted 599 by K2DRH at 2239Z. This was multi-hop Es to the geomagnetic equator!

“A strong 6 meter opening between Arizona, California and Washington State to Japan took place July 24-25.

“On the July 26, CO8LY FL20 worked into the Midwest and Rocky Mountain States via double hop Es. Spotted by K0GU DN70 and NW0W EM47 until 1650z. I logged him on 50.108 MHz at 1758 Z.”

Jon also passed along this late news: “July 30, J69MV, VP2ETE, FG8OJ and KV4FZ were in to IA, MO, OK and W4 around 1630z via double hop E-skip on 50 MHz.”

Check this map for live lightning detection across North America:

This was passed on by Dick Bingham, W7WKR, who lives way off the grid at Stehekin, Washington, which is at the northwest end of Lake Chelan.

He advises making sure Strikes, Detectors Used and Sound are turned on for the lightning app.

Also check these pages:

Pierre Desjardins, VE2PID, of Sherbrooke, Quebec asked about the predicted International Sunspot Number at and what the numbers in parenthesis mean.

The numbers above the parenthesis are predicted smoothed international sunspot numbers, which use a 13-month average.  A zero means there is zero uncertainty about the number, because all of the data used to calculate this smoothed number are known values. But as we move into the future, there is more uncertainty. For the latest month, we already know half the data used to calculate the average, but the other half of the data is predicted.  So the higher numbers in parenthesis indicate greater uncertainty.

Rob Steenburgh, AD0IU, who works as a space weather forecaster at NOAA said the predictions here are from the McNish-Lincoln technique, from a paper published in 1949.  The method is described here:

Rob is checking with a colleague to find out exactly what the numbers represent and perhaps the scale used.

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

My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at and .

Click on “Download this file” to download the archive and ignore the security warning about file format. Pop-up blockers may suppress download. I’ve had better luck with Firefox than Internet Explorer.

Monthly propagation charts between four USA regions and twelve overseas locations are at

Instructions for starting or ending e-mail distribution of ARRL bulletins are at

Sunspot numbers for July 23 through 29 were 27, 54, 41, 38, 53, 56, and 66, with a mean of 47.9. 10.7 cm flux was 89.4, 92.2, 94, 97, 100.1, 101.1, and 100.7, with a mean of 96.4. Estimated planetary A indices were 23, 7, 9, 8, 11, 9, and 5, with a mean of 10.3. Estimated mid-latitude A indices were 21, 6, 9, 9, 13, 9, and 7, with a mean of 10.6.



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