Tad Cook, K7RA, Seattle, reports: The 10.7-centimeter solar flux density was 88.1 on Wednesday, November 4, the highest since October 14, 2016, when it was 92.8. The average daily solar flux for that week as reported in this bulletin was 76.9, and average daily sunspot number was 18.7, so activity 4 years ago was similar to recent activity; in fact those numbers closely match the flux and SSN in last week’s bulletin. But in 2016, Solar Cycle 24 was declining, reaching a minimum about 3 years later in December 2019.

The daily solar flux is measured at noon local time (GMT –8 hours) in Penticton, British Columbia, but actually three daily measurements are taken, at 1800 UTC, 2000 UTC, and 2200 UTC.

Solar flux has been steadily increasing since the 2000 UTC reading on November 2. The three daily readings through November 5 were 81.6, 81.9, 82.9, 82.9, 83.7, 86.9, 88.1, 89, 91.1, 90.7, and 92. But the daily 2000 UTC reading is always reported as the official number for the day. (Spaceweather.com lists the daily flux values.)

Average daily sunspot number during the October 29 – November 4 reporting week was 21.3, compared to 17 over the previous 7 days. Average daily solar flux was 81.6, compared to 76.9 reported last week.

Average daily planetary A index this week was 6.3, down from 12.3 last week. Average daily mid-latitude A index was 4.9, down from 9.9 last week.

Spaceweather.com reported at 0703 UTC on November 3 that the new sunspot group produced a minor solar flare, and a pulse of UV radiation “briefly ionized Earth’s upper atmosphere, causing a low-frequency radio blackout over the Indian Ocean.”

Another flare occurred at 0022 UTC on November 5, which caused a brief blackout over Australia and the Pacific Ocean, causing signals below 10 MHz to fade.”

Check the STEREO satellite images: 360° view | Conventional format. A large, new sunspot group, AR2781, is the largest so far in new Solar Cycle 25, according to Spaceweather.com. It should be geo-effective (facing Earth) over the next 10 days.

Predicted solar flux is 88 on November 5 – 10; 83 on November 11; dropping to 75, 74, and 75 on November 12 – 14; 76 on November 15 – 21; 75 on November 22 – 27; 74 on November 28 – 29; 72 on November 30 – December 5; 74 on December 6 – 10; 75 on December 11; 76 on December 12 – 18, and 75 on December 19.

Predicted planetary A index is 5, 8, and 8 on November 5 – 7; 5 on November 8 – 16; 10, 5, 10; and 15 on November 17 – 20; 12 on November 21 – 22; 8, 10, and 12 on November 23 – 25; 5 on November 26 – 27; 10 on November 28; 5 on November 29 – December 13; then 8, 5, and 8 on December 14 – 16; 12 on December 17, and 10 on December 18 – 19. Flux and geomagnetic predictions are updated daily.

Here’s the geomagnetic activity forecast for November 6 – December 2 from F.K. Janda, OK1HH.

The geomagnetic field will be:

• quiet on November 6-7, 9-11, December  1-2

• quiet to unsettled on November 8, 12-15, 19, 26-27, 30

• quiet to active on November 16-18, 22-25, (29)

• unsettled to active November 21, (28)

• active to disturbed November 20

• Solar wind will intensify on November (18-20,) 21-25 (30, December 2)

Parentheses mean lower probability of activity enhancement.

This weekend is the CW portion of ARRL November Sweepstakes, which runs from 2100 UTC Saturday until 0259 UTC on Monday.

Here’s a cool photo of the WWV antennas in Colorado, and from an unusual perspective.

Sunspot numbers for October 29 – November 4, 2020 were 35, 32, 26, 12, 11, 15, and 18, with a mean of 21.3. The 10.7-centimeter flux was 84.6, 79.6, 76.8, 77.3, 81.6, 82.9, and 88.1, with a mean of 81.6. Estimated planetary A indices were 14, 5, 6, 10, 3, 3, and 3, with a mean of 6.3. Middle latitude A index was 11, 4, 6, 8, 2, 2, and 1, with a mean of 4.9.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out K9LA’s 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.

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