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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
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 are at www.arrl.org/w1aw-bulletins-archive-propagation.
More good information and tutorials on
propagation are at http://k9la.us.
Also, check
this QST 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 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
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