Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:
Solar activity continued to decline this week, with the average daily sunspot number dropping from 91.1 to 36.6, and average solar flux at 95.7, down from 107.6 the week prior.
We have not seen lower values since mid-April in bulletin ARLP015
with average sunspot number at 34.4, and the end of February in ARLP008 with the average solar flux at 95.4.
This was noticeable over the past week on 10 and 12 meters, but there must still be some daily sporadic E, from what I have seen on an email list devoted to 10-meter propagation beacons. I have one myself — K7RA/B transmitting CW from CN87uq on 28.2833 MHz.
The outlook from the United States Air Force space weather group shows a meager forecast for solar flux, according to forecasters Sadovsky and Ciopastu on Wednesday.
Predicted solar flux over the next month never rises above 100, having values of 100 for August 4 – 7; 98 and 96 on August 8 – 9; 98 on August 10 – 14; 100 on August 15 – 16; 98 on August 17 – 18; 96, 96, and 98 on August 19 – 21; 96 again on August 22 – 23; 92 on August 24 – 28; 90 and 92 on August 29 – 30; 94 on August 31 – September 1; 96 on September 2 – 3, and 98 on September 4 – 10.
Predicted planetary A index is 8 on August 4; 5 on August 5 – 7; 8, 14, and 12 on August 8 – 10; 8 on August 11 – 12; 5 on August 13 – 16; 22 on August 17; 15 on August 18 – 19; 8 on August 20 – 21; 5 on August 22 – 25; 10 and 12 on August 26 – 27; 5 on August 28 – 29; 12 and 10 on August 30 – 31, and 5 on September 1 – 6.
Sunspot numbers for July 28 – August 3 were 50, 40, 27, 39, 32, 31, and 37, with a mean of 36.6. The 10.7-centimeter flux was 93, 90.8, 94.3, 95.4, 97.8, 98.8, and 99.9, with a mean of 95.7. Estimated planetary A indices were 7, 4, 7, 11, 8, 9, and 8, with a mean of 7.7. Middle latitude A index was 9, 6, 8, 12, 8, 10, and 7, with a mean of 8.6.
Send your tips, questions, or comments to k7ra@arrl.net.
A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…” and check out the Propagation Page of Carl Luetzelschwab, K9LA. A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website