The K7RA Solar Update

Tad Cook, K7RA, Seattle, reports:

Last week, we reported a return of sunspot activity on September 29, after a 16-day absence, but the new activity lasted only 6 days. The average daily sunspot number declined from 9.6 to 1.6, while the average daily solar flux rose slightly from 68.4 to 68.9. The average planetary A index increased from 7.7 to 14.1, while the mid-latitude A index jumped from 6.1 to 10.3.

Predicted solar flux is 72 on October 11 – 17; 71 on October 18; and 69 on October 19 – November 24.

The predicted planetary A index is 12, 8, 5, 12, and 8 on October 11 – 15; 5 on October 16 – 17; 10, 25, 14, 8, and 12 on October 18 – 22; 8 on October 23 – 25; 10 on October 26; 5 on October 27 – November 2; 22 and 35 on November 3 – 4; 15 on November 5 – 6; 10, 8, 5, 10, and 8 on November 7 – 11; 5 on November 12 – 13; 10, 25, 14, 8, and 12 on November 14 – 18; 8 on November 19 – 21; 10 on November 22, and 5 on November 23 – 24.

Conditions will probably continue at somewhat marginal levels because of weak solar activity. It is widely believed that Cycle 24 should reach solar minimum in 2020. The NOAA Space Weather Prediction Center (SWPC) has the latest projections.

Sunspot numbers for October 4 – 10 were 11, 0, 0, 0, 0, 0, and 0, with a mean of 1.6. The 10.7-centimeter flux was 67.2, 68.7, 68.6, 69.5, 68.8, 69.5, and 69.8, with a mean of 68.9. Estimated planetary A indices were 4, 9, 6, 24, 21, 17, and 18, with a mean of 14.1. Estimated mid-latitude A indices were 4, 8, 5, 13, 16, 14, and 12, with a mean of 10.3.

ARRL News Letter on Oct 11, 2018