SB PROP @ ARL $ARLP001
ARLP001 Propagation de K7RA
ZCZC AP01
QST de W1AW
Propagation Forecast Bulletin 1 ARLP001
From Tad Cook, K7RA
Seattle, WA January 3, 2025
To all radio amateurs
SB PROP ARL ARLP001
ARLP001 Propagation de K7RA
Currently a geomagnetic storm is raging. On January 1-2, Alaska's college A
index reached 113.
Predicted planetary A index is 12 on January 3, then 18, 18, 12, 10 and 8 on
January 4-8, 5 on January 9-10, 10 and 8 on January 11-12, 5 on January
13-15, 12 on January 16, 10 on January 17-20, 5 on January 21-25, then 8, 50,
20 and 8 January 26-29.
Predicted solar flux is 215 on January 3-4, then 205, 210, 205 and 205 on
January 5-8, then 200, 170 and 165 on January 9-11, 170 on January 12-13, 175
on January 14-15, 180, 190, 200, 210 and 220 on January 16-20, 230 on January
21-25, 240 on January 26-27, then 220, 200 and 195 on January 28-30.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere -
January 2, 2025 from OK1HH:
"Considering the high solar flare activity, there was a relatively high
probability of an increase in geomagnetic activity during the Christmas
holidays.
"But currents of enhanced solar wind avoided the Earth and therefore it was
surprisingly quiet for a relatively long period from Christmas almost until
the end of the year, more precisely from 25 to 30 December.
"Strong solar flares in the last two days of December were followed by CMEs
that were at least partially directed towards the Earth. This prompted all
geomagnetic field activity forecasters to jointly and indiscriminately
predict the occurrence of geomagnetic disturbances and auroras for 31
December and 1 January.
"Particles ejected by the second of the major eruptions hit the Earth more
effectively. Therefore, the geomagnetic disturbance on 31 December was
weaker. The major disturbance on January 1, 2025 was accompanied by beautiful
auroras.
"At first approximation, the unexpected development of ionospheric shortwave
propagation on New Year's Day may have seemed surprising. Not only were they
not bad, but their development was irregular, while the MUF values were even
above average. The cause can be found also in the previous calm development
(25 to 30 December) and also in the fact that the solar wind speed started to
increase gradually only from 1 January.
"The most active regions on the Sun now fall behind the western limb of the
solar disk. Therefore, solar activity will slowly decrease. But it will be
sufficient to open all shortwave bands. At the same time, the Earth's
magnetic field activity will also be decreasing, so the evolution of
ionospheric propagation conditions should be more stable, while remain mostly
above average on most days."
An article from "yourweather.co.uk" regarding the solar max:
https://bit.ly/41ZnwUq [
https://bit.ly/41ZnwUq ]
Latest video from Dr. Tamitha Skov, WX6SWW (Space Weather Woman):
https://youtu.be/k3gxVE74Xa0 [
https://youtu.be/k3gxVE74Xa0 ]
For more information concerning shortwave radio propagation, see
www.arrl.org/propagation [
http://www.arrl.org/propagation?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL] and the ARRL Technical Information Service web page at:
www.arrl.org/propagation-of-rf-signals [
http://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 [
http://arrl.org/the-sun-the-earth-the-ionosphere ] .
An archive of past propagation bulletins are at:
www.arrl.org/w1aw-bulletins-archive-propagation [
http://arrl.org/w1aw-bulletins-archive-propagation ] . More good information
and tutorials on propagation are at
http://k9la.us [
http://k9la.us/ ] .
Also, check this: "Understanding Solar Indices" from September 2002 QST.
https://bit.ly/3Rc8Njt [
https://bit.ly/3Rc8Njt ]
Instructions for starting or ending email subscriptions to ARRL bulletins are
at:
www.arrl.org/bulletins [
http://arrl.org/bulletins ] .
Sunspot numbers for December 26, 2024 through January 1, 2025 were 211, 233,
213, 209, 162, 172, and 163 with a mean of 194.7. 10.7 cm flux was 255.8,
258.5, 260.3, 254.7, 223.5, 216.2, and 219.2 with a mean of 241.2. Planetary
A index was 3, 3, 4, 5, 7, 10 and 86 with an average of 16.9. Middle latitude
A Index was 3, 5, 7, 10, 7, 10, and 48, with a mean of 12.9.
NNNN
/EX
ARRL(R) The National Association for Amateur Radio(R)
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ARLP001 Propagation de K7RA