| SB PROP @ ARL $ARLP050
ARLP050 Propagation de K7RA
ZCZC AP50
QST de W1AW
Propagation Forecast Bulletin 50 ARLP050
From Tad Cook, K7RA
Seattle, WA December 30, 2024
To all radio amateurs
SB PROP ARL ARLP050
ARLP050 Propagation de K7RA
Strong solar activity continues, with worldwide propagation on 10 and 12 meters quite commonplace.
Predicted solar flux is 255, 250, 210, 200, and 195 on December 30, 2024 through January 3, 2025, 190 on January 4-5, 170 on January 6, 160 on January 7-8, then 165, 170 and 165 on January 9-11, 170 on January 12-13, 175 on January 14-15, 180 on January 16, 185 on January 17-18, 200 on January 19-23, 185 on January 24-26, 175 on January 27, and 180 on January 28-30, 2025.
Predicted planetary A index is 8, 50, 20 and 8 on December 30, 2024 through January 2, 2025, 5 on January 3-4, 8 on January 5-6, 5 on January 7-9, then 12, 10 and 8 on January 10-12, 5 on January 13-15, then 8, 10 and 10 on January 16-18, 8 on January 19-23, and 5 on January 24-31.
The latest from F. K. Janda, OK1HH:
“A cooling water pipe burst in the server room of the Joint Science Operations Center (JSOC) at the Solar Dynamics Observatory (SDO) in California on 26 November 2024. Since then, data from the Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Array (AIA) instruments have been unavailable.
“On the popular website www.solarham.com on the bottom left, we usually find information on activity on the far side of the Sun (at www.solarham.com/farside.htm) that would be needed to predict developments around the Christmas season, for example. This is because we were expecting the rise of active regions on the Sun that were very active during the last solar revolution and whose high activity we know about thanks to CMEs and the influx of protons from flares on the Sun’s far side.
“As expected, active regions on the Sun did appear and they were not alone. Moderate solar flares are the order of the day, while we have been expecting a geomagnetic disturbance during the Christmas holidays since after the CME registration. But the particle clouds missed the Earth, the disturbance did not take place, and ionospheric shortwave propagation conditions remained above average.
“But even better propagation conditions are likely to await us next year. The high solar activity in October this year was probably not yet the peak of the 25th cycle – that is yet to come!”
From Space.Com, “The Sun in 2025: How the solar cycle will shape our year ahead”:
https://bit.ly/3DA4N7L
The latest report from Dr. Tamitha Skov, WX6SWW:
https://youtu.be/qPI4_otUAME
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 is at: www.arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at, http://k9la.us.
Also, check this 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 December 19 through 25, 2024 were 96, 148, 152, 176, 199, 219, and 218 with a mean of 172.6. 10.7 cm flux was 175, 184, 201.2, 223.3, 238.3, 258.5, and 252.7 with a mean of 219. Planetary A index was 11, 13, 16, 14, 12, 12, and 5 with an average of 11.9. Middle latitude A Index was 9, 10, 13, 15, 11, 9, and 5, with a mean of 10.3.
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