| SB PROP @ ARL $ARLP049
ARLP049 Propagation de K7RA
ZCZC AP49
QST de W1AW
Propagation Forecast Bulletin 49 ARLP049
From Tad Cook, K7RA
Seattle, WA December 20, 2024
To all radio amateurs
SB PROP ARL ARLP049
ARLP049 Propagation de K7RA
Excellent HF conditions greeted hams in the ARRL 10-Meter contest last weekend. Recent indicators show a sudden shift to two digit daily sunspot numbers from three, and although there is nothing significant about 100, it makes one notice.
All daily sunspot numbers this week were 97 or less.
Perhaps this indicates a move off of solar maximum, or to a future with a second maximum.
Solar activity was way, way down this week with an average daily sunspot number at just 88.
Predicted solar flux is 175, 180, 180, 185 and 180 on December 20-24, 175 on December 25-26, 180 on December 27, 185 on December 28-29, 180 on December 30 through January 2, 2025, and 175 on January 3-4, 170 on January 5-6, 160 on January 7-8, then 165, 179, 165, and 170 on January 9-12, 165 on January 13-14, 170 on January 15-16, 175 on January 17-18, 180 on January 19-23, and 185 on January 24-25.
The forecast for Planetary A index shows a quiet 5 on December 20-22, 8 on December 23-24, and 5 on December 25 through January 4, 2025, then 15 and 8 on January 5-6, 5 on January 7-9, then 12, 10 and 8 on January 10-12, and 5 on January 13-31.
OK1HH does not seem to have a commentary this week.
The latest report from Dr. Tamitha Skov, WX6SWW:
https://youtu.be/wClI7PKn3K0
Send your tips, reports, observations, questions, and comments to k7ra@arrl.net. When reporting observations, don’t forget to tell us which mode you were operating.
For more information concerning shortwave radio propagation, see www.arrl.org/propagation and the ARRL Technical Information Service web page at www.arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere.
An archive of past propagation bulletins is at www.arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us.
Also, check this article: “Understanding Solar Indices” from September 2002 QST.
https://bit.ly/3Rc8Njt
Instructions for starting or ending email subscriptions to ARRL bulletins are at www.arrl.org/bulletins.
Sunspot numbers for December 12 through 18 2024 were 91, 82, 86, 97, 90, 88, and 82 with a mean of 88. 10.7 cm flux was 172, 163.7, 170.5, 172, 166.7, 170, and 173.5 with a mean of 169.8. Estimated planetary A indices were 6, 4, 10, 12, 14, 29, and 15, with a mean of 12.9. Middle latitude A Index was 4, 2, 8, 9, 11, 20, and 12, with a mean of 9.4.
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