SB PROP @ ARL $ARLP003
ARLP003 Propagation de K7RA
ZCZC AP03
QST de W1AW
Propagation Forecast Bulletin 3 ARLP003
From Tad Cook, K7RA
Seattle, WA January 17, 2025
To all radio amateurs
SB PROP ARL ARLP003
ARLP003 Propagation de K7RA
Sorry to say this is the last ARRL Propagation Forecast Bulletin I will
write. I took over in 1991 from Ed Tilton, W1HDQ when he was too ill and weak
to continue, and now with ALS I have similar problems.
Geomagnetic influencers were more stable this week (planetary A index shifted
from 16.9 to 10.7) and solar indicators were weaker. Average daily sunspot
number changed from 159.1 to 103.3 and average daily solar flux from 184.3 to
161.9.
Predicted activity indicates solar flux at 210 on January 17-18, 215 on
January 19, 220 on January 20-21, 215 on January 22, 220 on January 23-24,
170 on January 25-26, 175 on January 27-28, 170 on January 29-30, then 165
and 160 on January 31 through February 1, 155 on February 2-3, 150 on
February 4-6, 145 on February 7-8, 150 on February 9, 145 on February 10-12,
150 on February 13, 155 on February 14-15, 160 on February 16, and 165 on
February 17-20.
The forecast for planetary A index is 15, 12 and 8 on January 17-19, 8 on
January 20-21, 5 on January 22-30, then 20 on January 31 through February 2,
then 15, 12, 12 and 10 on February 3-6, then 5 on February 7-9, 8 on February
19-11, 5 on February 12, 8 on February 13-16 and 5 on February 17-26.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere,
January 16, 2025, from F. K. Janda, OK1HH:
"There is no indication that the prediction of an upsurge in solar activity
starting in mid-January will come to pass. The development is quieter, with
no major solar flares occurring. The sunspot groups that are currently
observable from Earth have stable magnetic fields. More important flares are
therefore rather unlikely.
"The geomagnetic field, while not calm, is not disturbed. Intervals of
quiescence alternate irregularly with slight upswings in activity.
Ionospheric shortwave propagation conditions are therefore not as good as we
had hoped based on the predicted rise in solar activity, but they are not bad
either. This type of development is likely to continue."
The latest from the Royal Observatory of Belgium:
https://www.sidc.be [
https://www.sidc.be ]
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 QST article: "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 January 9 through 15, 2025 were 126, 105, 85, 99, 100,
106, and 102 with a mean of 103.3. 10.7 cm flux was 162.2, 156.9, 156, 158.4,
159.7, 166.4, and 173.5 with a mean of 161.9. Planetary A index was 10, 12,
7, 7, 11, 12 and 16, with an average of 10.7. Middle latitude A Index was 9,
11, 5, 6, 9, 10, and 11, with a mean of 8.7.
NNNN
/EX
ARRL(R) The National Association for Amateur Radio(R)
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ARLP003 Propagation de K7RA