The K7RA Solar Update

Tad Cook, K7RA, Seattle, reports: The past week was a good one for HF propagation. Average daily sunspot numbers doubled from the previous week, rising from 13.6 to 27, while average daily solar flux rose from 72.6 to 84.3. Average daily geomagnetic numbers were lower, with average planetary A index declining from 21.1 to 9.9 and average daily mid-latitude A index from 17.1 to 7.6. Last Friday was the autumnal equinox, so we should see a seasonal improvement in HF conditions.

Predicted solar flux is 91 on September 28-October 1; 88 on October 2-4; 90, 95, 90, 85, 76, 75, 74, and 73 on October 5-12; 72 on October 12-15; 71, 74, 73, 78, 80, 87; and 90 on October 16-22; 95 on October 23-November 2; 90, 85, 76, 75, 74, and 73 on November 3-8, and 72 on November 9-11.

Predicted planetary A index is 32, 26, 14, 12, and 6 on September 28-October 2; 5 on October 3-10; 25 on October 11-13; 20 and 15 on October 14-15; 8 on October 16-17; 5 on October 18-21; 16, 8, 20, 25, 20, 10, and 8 on October 22-28; 5 on October 29-November 6; 25 on November 7-9, and 20 and 15 on November 10-11.

Sunspot numbers for September 21-27, 2017 were 22, 22, 12, 22, 36, 40, and 35, with a mean of 13.6. The 10.7-centimeter flux was 73, 77.5, 81.2, 86.9, 89.9, 90.7, and 91, with a mean of 72.6. Estimated planetary A indices were 7, 5, 5, 6, 5, 4, and 37, with a mean of 21.1. Estimated mid-latitude A indices were 7, 5, 4, 5, 5, 3, and 24, with a mean of 17.1.

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