Tad Cook, K7RA, Seattle, reports:

Solar activity was weaker this week, with the average daily sunspot number declining from 34.9 last week to 13.9 this week. The average was affected by the one day with no sunspots, Saturday, June 12.

Average daily solar flux dropped from 77.7 to 75.2. The Penticton observatory in British Columbia — the source for the 10.7-centimeter solar flux reading — did not report a noon reading on June 16, so the morning (76.9 at 1700 UTC) and afternoon readings (77.1 at 2300 UTC) were averaged to come up with 77 as a reasonable approximation.

Normally, the local noon reading (2000 UTC) is the official number for the day. You can get the three daily readings direct from the Dominion Radio Astrophysical Observatory.

Predicted solar flux for the near term is 75 on June 17 – 20; 80 on June 21 – 24; 77 on June 25 – 28; 78 on June 29 – July 7; 79 on July 8 – 10; 77 on July 11 – 13; 76 on July 14 – 16, and 80 on July 18 – 20.

Predicted planetary A index is 14 and 12 on June 17 – 18; 5 on June 19 – 25; 7 on June 26; 5 on June 27 – July 4; 15, 10, and 8 on July 5 – 7; 5 on July 8; 8 on July 9 – 11; 10, 12, 20, and 12 on July 12 – 15, and 5 on July 16 – 22.

Something big may be about to happen on the sun. ”We call it the Termination Event,” says Scott McIntosh in this article by Tony Phillips.

Sunspot numbers for June 10 – 16 were 29, 13, 0, 22, 11, 11, and 11, with a mean of 13.9. The 10.7-centimeter flux was 73.3, 77.3, 77.6, 68.9, 76.8, 75.5, and 77, with a mean of 75.2. Estimated planetary A indices were 5, 10, 10, 7, 4, 17, and 14, with a mean of 9.6. Middle latitude A index was 5, 11, 8, 7, 7, 15, and 15, with a mean of 9.7.

ARRL News Letter on June 17, 2021