Subj : The K7RA Solar Update
To   : QST
From : ARRL de WD1CKS
Date : Fri Dec 20 2024 21:10:13

 12/20/2024 

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[1]

Send your tips, reports, observations, questions, and comments to
k7ra@arrl.net[2]. When reporting observations, don't forget to tell us
which mode you were operating.

For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation[3] and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals[4]. For
an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere[5] .

An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation[6] . More good
information and tutorials on propagation are at http://k9la.us/[7] .

Also, check this article:

https://bit.ly/3Rc8Njt[8]

"Understanding Solar Indices" from September 2002 QST.

Instructions for starting or ending email subscriptions to ARRL
bulletins are at http://arrl.org/bulletins[9] .

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.

ÿ


[1] https://youtu.be/wClI7PKn3K0
[2] mailto:k7ra@arrl.net
[3] http://www.arrl.org/propagation
[4] http://arrl.org/propagation-of-rf-signals
[5] http://arrl.org/the-sun-the-earth-the-ionosphere
[6] http://arrl.org/w1aw-bulletins-archive-propagation
[7] http://k9la.us/
[8] https://bit.ly/3Rc8Njt
[9] http://arrl.org/bulletins

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