The K7RA Solar Update

Tad Cook, K7RA, Seattle, reports: Solar activity continues to be very weak, and the latest 45-day outlook seems to indicate more of the same ahead. Sunspots only appeared on 3 out of the 7 days in the August 5 – 11 reporting week, and these days were not consecutive.

Average daily sunspot numbers actually rose a little, from 6 to 9.9. Average daily solar flux softened from 74.8 to 73.7. Average daily planetary A index went from 8 to 6.3, while middle latitude averages were 7, down from 8.7 last week.

Predicted solar flux over the next few weeks shows a predicted maximum of only 75 on just one day, September 11. The solar flux forecast from USAF and NOAA shows 73 on August 13-14; 72 on August 15-19; 73 on August 20; 74 on August 21 – September 1; 73, 72, 72, 74, and 74 on September 2-6; 73 on September 7-10; 75 on September 11; 72 on September 12-15; 73 on September 16, and 74 on September 17 and beyond.

Predicted planetary A index is 8 on August 13-15; 5 on August 16-22; 8 on August 15-16; 5 on August 17-22; 8, 12, and 8 on August 23-25; 5 on August 26 – September 1; 8 and 12 on September 2-3; 8 on September 4-6; 5 on September 7-11; 12, 10, and 10 on September 12-14, and 5 on September 15-18.

Strangely, the planetary A index for September 5 is listed as 58, which I was certain was an error. I wrote to SWPC.Webmaster@noaa.gov and received no reply as yet.  This outlier value was repeated in Thursday’s forecast. Wednesday’s prediction was done by forecasters Stover and Houseal, and Thursday’s was from Trost and Houseal. I have not checked earlier forecasts to see when this value first showed up. New forecasts appear daily on the SWPC website.

OK1HH is away for another week, so two of his colleagues — Martina Pavelkova of RWC Prague, Astronomical Institute, Solar Department, Ondrejov, Czech Republic, and Tomas Bayer, RWC Prague, Institute of Geophysics of the ASCR, Prague, Department of Geomagnetism, Budkov Observatory — are sitting in to present the geomagnetic activity forecast for August 13 – 19.

• Activity level: mostly very low

• X-ray background flux (1.0-8.0 A): in the range A3.5-A7.0

• Radio flux (10.7 centimeters): a fluctuation in the range 70-75

• Events: class C (0-2/period), class M (0/period), class X (0/period),

• proton (0/period)

• Relative sunspot number (Ri): in the range 0-55

Geomagnetic activity forecast for the period August 13-August 19, 2021:

• Quiet: Aug 13-16, 19

• Unsettled: Aug 16-18

• Active: possible Aug 16-17

• Minor storm: 0

• Major storm: 0

• Severe storm: 0

Geomagnetic activity summary: Next week, we expect quiet-to-unsettled conditions generally. Until Sunday, August 15, we expect the quiet-to-unsettled level closer to the lower end of the scale.

After Monday, August 16, more unsettled conditions are possible. Between August 16 and August 18, more unsettled conditions are probable. Within this interval, an isolated active event is also possible.

I spotted an interesting item on Southgate Amateur Radio News.

Sunspot numbers for August 5 – 11 were 36, 0, 0, 11, 0, 0, and 22, with a mean of 9.9. The 10.7-centimeter flux was 74.3, 74.4, 73.7, 73.5, 73, 73.3, and 73.8, with a mean of 73.7. Estimated planetary A indices were 3, 7, 11, 5, 5, 7, and 6, with a mean of 6.3. Middle latitude A index was 3, 9, 9, 6, 6, 9, and 7, with a mean of 7.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out this propagation page.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Instructions for starting or ending email distribution of ARRL bulletins are on the ARRL website.

Share your reports and observations.