Tad Cook, K7RA, Seattle, reports: Solar activity was up this week. Average daily sunspot number increased from 26.9 to 46.1, and average daily solar flux was up 10.8 points to 90.9. Geomagnetic indicators were a little higher. Average daily planetary A index increased from 7.9 to 8.7, and average daily middle latitude A index from 5.4 to 6.3.
Two new sunspot groups emerged on November 26, another on November 28, and two more on November 30.
On December 1, Spaceweather.com announced a geomagnetic storm watch: “Minor geomagnetic storms are possible on December 3 when a CME might sideswipe Earth’s magnetic field. The storm cloud was hurled into space on November 29 by an erupting filament of magnetism in the sun’s southern hemisphere. According to NOAA computer models, the bulk of the CME should sail south of our planet with a near miss [or] just as likely as a glancing blow.”
Predicted solar flux for the next month has flux values peaking at 94 on December 27 – 28. The forecast sees values of 86 and 84 on December 2 – 3; 80 on December 4 – 5; 78 on December 6 – 7; 76 and 78 on December 8 – 9; 82 on December 10 – 12; 80 on December 13 – 14; 85 on December 15 – 21; 82 and 80 on December 22 – 23; 78 on December 24 – 25; 92 on December 26; 94 on December 27 – 28; 88 on December 29 – January 1; 85, 82, and 80 on January 2 – 4, and 82 on January 5 – 8.
Predicted planetary A index is 10, 16, 12, and 8 on December 2 – 5; 12, 10, and 8 on December 6 – 8; 5 on December 9 – 11; 8, 12, and 10 on December 12 – 14; 5 on December 15 – 16; 8 and 10 on December 17 – 18; 5 on December 19 – 25; 8 on December 26; 5 on December 27 – 29; 10 on December 30 – 31; 8 on January 1, and 5 on January 2 – 7.
Robert Marston, AA6XE, offered these observations:
“We now stand at exactly 2 years since the Solar Cycle 24/25 minimum was recorded, and the most notable attribute of Solar Cycle 25 is its slow climb out. We have seen bursts of activity from the sun, where numerous active regions pop up with only a handful actually developing into numbered sunspot groups. The bulk of new regions that form quickly decay away.”
There will be more from AA6XE in Friday’s report and bulletin.
Sunspot numbers for November 25 – December 1 were 20, 52, 53, 53, 47, 61, and 37, with a mean of 46.1. The 10.7-centimeter flux was 93.6, 92.3, 91.8, 92.2, 89.8, 90, and 86.4, with a mean of 90.9. Estimated planetary A indices were 5, 4, 5, 9, 9, 11, and 18, with a mean of 8.7. Middle latitude A index was 3, 3, 3, 7, 6, 8, and 14, with a mean of 6.3.
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.