Register Account

Login Help


The K7RA Solar Update


Solar activity is still soft, although sunspot numbers and solar flux both increased this week. Average daily sunspot numbers for August 6-12 increased from 70.3 to 82.3, compared to the previous seven days, and average daily solar flux went from 104.5 to 112.4. Geomagnetic activity was moderate.

Predicted solar flux for the near term is 95 on August 14-15, 90 on August 16-21, 95 on August 22, 100 On August 23-26, 105 on August 27-28, 110 on August 29-31, and then peaking at 115 on September 1-7. Solar flux drops below 100 on September 13-18.

Predicted planetary A index is 5 on August 14-15, 25 on August 16, 18 on August 17, 8 on August 18, 5 on August 19-20, 10 on August 21-22, 12 on August 23, 10 on August 24, 5 on August 25-26, 12 on August 27, 10 on August 28-29, 5 on August 30 through September 1, then 12, 22 and 15 on September 2-4, then 20, 22, 12 and 8 on September 5-8, and 5 on September 9-12.

F.K. Janda, OK1HH, of the Czech Propagation Interest Group predicts quiet geomagnetic conditions on August 14, mostly quiet August 15, quiet to unsettled August 16, quiet to active August 17, active to disturbed August 18, quiet to unsettled August 19-20, quiet August 21, quiet to unsettled August 22—25, active to disturbed August 26, quiet to active August 27, quiet to unsettled August 28-30, mostly quiet on September 1, active to disturbed September 2, quiet to active September 3-4, mostly quiet September 5-7, quiet to active September 8 and quiet on September 9.

He expects an increase in solar wind on August 15-17, 25-27, August 31 to September 1, and September 5-6. OK1HH says the August 15-17 increase is less probable when compared to subsequent dates.

The Australian Space Forecast Centre issued a geomagnetic disturbance warning at 0147 UTC on August 14. The warning said a partial halo CME observed in LASCO C2 imagery at 1448 UTC on August 12 associated with the long duration B7.0 flare and the filament eruption from the southwest quadrant is expected to cause a glancing blow early in the UTC day on August 16. Expect periods of unsettled to active levels in Australian region with chance of isolated periods of minor storms at higher latitudes.

Richard Camp, WA7VGN, lives in Las Vegas, Nevada (DM26jg) and sent a message titled “6 meter meteor scatter” about conditions on August 12. Six meters was wide open when he made a contact on 50.125 MHz using SSB. But when they tried to move off that frequency, it took four attempts on different frequencies to find a clear spot to talk. Richard said the band sounded like 20 meters at times with S9 signals all around. The next day 6 meters sounded dead.

I don’t recall if we’ve looked at these bulletins before, from the American Association of Variable Star Observers.

Here is a recent monthly issue, from March 2015:

They have interesting information on Sudden Ionospheric Disturbances, sunspot counts and solar flares.

Note the startling difference between current bulletins and one from over 60 years ago:

Issues of this bulletin online go back 70 years, to 1945!

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 IE.

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 August 6 through 12 were 80, 95, 92, 87, 67, 87, and 68, with a mean of 82.3. 10.7 cm flux was 121.6, 121.6, 121, 114.5, 106.2, 102.8, and 99.2, with a mean of 112.4. Estimated planetary A indices were 11, 20, 12, 10, 9, 8, and 12, with a mean of 11.7. Estimated mid-latitude A indices were 12, 17, 15, 10, 13, 8, and 12, with a mean of 12.4.



Instragram     Facebook     Twitter     YouTube     LinkedIn