ZCZC AP48
QST de W1AW
Propagation Forecast Bulletin 48 ARLP048
From Tad Cook, K7RA
Seattle, WA December 13, 2024
To all radio amateurs
SB PROP ARL ARLP048
ARLP048 Propagation de K7RA
Average daily sunpsot number plummeted to 104.4.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for
"The high solar activity in October this year suggests that this may have been
that solar activity will not continue to rise. On the contrary, it may well be in October and that we can look forward to a second maximum. This could take pl e followed by a decline.
"Solar activity in November was lower and December's is even lower. The expecte mber, did not take place because the CME did not affect the Earth. However, the s continued and a large flare occurred. It happened on 8 December at around 090
geomagnetic disturbance followed and the changes in ionospheric shortwave prop
In December, the Sun is quieter, and large sunspot groups do not occur in its p
are to the south of the solar equator, and their area is about half that of th f AR3917 is slowly getting larger and with it the likelihood of a larger flare
The Earth's ionosphere has been repeatedly affected in recent days by increased which, while causing a slight rise in MUF, have been more pronounced in the ion n, which has had a negative effect on the longer shortwave bands.
More meteors are arriving at Earth these days. The swarm is called the Geminids 4. Therefore we can observe more frequent occurrences of the sporadic E layer. ls on the longer shortwave bands, propagation through ionospheric waveguides is form one of the walls of the waveguide, but also enable its termination. Which
Predicted solar flux is 165 on December 13 to 15, 160 and 165 December 16 and 1
190 on December 20 to 22, 185 on December 23 and 24, 180 on December 25 and 26 .
Predicted planetary A index is 5 on January 13 and 14, 8 on January 15 and 16,
Flare blasts South Africa:
https://bit.ly/3Do6nJJ
STCE Newsletter Online version:
http://www.stce.be/newsletter/newsletter.php
PDF version:
http://www.stce.be/newsletter/pdf/2024/STCEnews20241212.pdf
Send your tips, reports, observations, questions and comments to
k7ra@rrl.net. l us which mode you were operating.
For more information concerning shortwave radio propagation, see
http://www.arr tion Service web page at
http://arrl.org/propagation-of-rf-signals.
For an explanation of numbers used in this bulletin, see
http://arrl.org/the-su
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-a
More good information and tutorials on propagation are at
http://k9la.us/.
Check "Understanding Solar Indices" from September 2002 QST at
https://bit.ly/3
Instructions for starting or ending email subscriptions to ARRL bulletins are a
Sunspot numbers for December 5 through 11 2024 were 101, 103, 91, 103, 94, 125, .6, 177.5, 182.5, 177.7 172.5, 171.9, and 160.5 with a mean of 170.9. Estimated d 7, with a mean of 8. Middle latitude A Index was 3, 6, 9, 6, 6, 6, 10, and 5, NNNN
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