ARLP051 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 51  ARLP051
>From Tad Cook, K7RA
Seattle, WA  December 18, 2020
To all radio amateurs 

ARLP051 Propagation de K7RA

Solar activity declined recently, with weekly average daily sunspot
numbers reported in this bulletin slipping from 57.6 to 28.9 and
then 17.4 over this past week.

Solar flux averages also slipped from 108.1 in bulletin ARLP049 to
91.9 in ARLP050 to 82.1 over the most recent week.

The latest solar flux prediction also appears soft. Solar flux is
expected to peak at 86 on December 26-28, hit a low at 82 on January
1-10, then peak again at 86 on January 21-24.

Predicted values over the next 45 days are 82 on December 18-24, 83
on December 25, 86 on December 26-28, then 85, 84 and 83 on December
29-31, 82 on January 1, 2021 through January 10, then 83, 83 and 84
on January 11-13, 85 on January 14-20, 86 on January 21-24, then 85,
84 and 83 on January 25-27, and 82 on January 28-31.

Predicted planetary A index is 5 on December 18-20, then 12 on
December 21, 8 on December 22-25, 5 on December 26, 2020 through
January 4, 2021, then 10 on January 5-6, 5 on January 7-12, 8 on
January 13, 5 on January 14-16, then 10, 12 and 10 on January 17-19,
8 on January 20-21, and 5 on January 22-31.

Geomagnetic activity forecast for the period December 18, 2020 to
January 12, 2021 from F.K. Janda, OK1HH.

"Geomagnetic field will be:
quiet on: December 28, January 4, 12
quiet to unsettled on: December 23, 29, 31, January 1, 3-4
quiet to active on: December 18, 24-27, 30, January 6, 8, 10-11
unsettled to active: December 19, 22, January 2, 5, 7, 9
active to disturbed: December 20-21
"Solar wind will intensify on: December (20,) 21 (-23, 25,) 27, (28-29,)
(January 1-3, 7-8).

"Parenthesis means lower probability of activity enhancement."

I noticed after last weekend's ARRL 10 Meter Contest, K7RL claimed
an impressive score of 379,680. Then I checked his page on
Not only is he surrounded by salt water on an island in Puget Sound,
but check out that amazing collection of steel and aluminum in the

He commented to the Western Washington DX Club email list, "That was
much more fun than expected. Every contest has that moment when an
interesting mult calls in, or you hit a great opening. My moment was
being called by ZD7BG on SSB.

"When the big openings hit both days, you had to be ready to step on
the gas and run like crazy because it could end just as quickly.
There was always some activity, it was mostly a matter of volume and
signal strength. Some signals lasted seconds, if even that, while
others were there almost all weekend like KV0Q and K0RF."

Another impressive effort, but on a much different scale, was
K6ARK's solo SOTA operation:

The National Science Foundation on a strong Solar Cycle 25:

Celebrating the return of sunspots in New Zealand:

Because this bulletin posts on Fridays, you might think we would
skip the next two issues, which are due on December 25 and January
1. But we won't. Expect both issues on both Fridays. But you won't
see a bulletin preview in the ARRL Letter, which due to the holidays
is suspended until Thursday January 7, 2021.

If you would like to make a comment or have a tip for our readers,
email the author at, Den här e-postadressen skyddas mot spambots. Du måste tillåta JavaScript för att se den..

For more information concerning radio propagation, see and the ARRL Technical Information
Service web page at, For
an explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good
information and tutorials on propagation are at

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for December 10 through 16, 2020 were 11, 11, 24,
14, 25, 25, and 12, with a mean of 17.4. 10.7 cm flux was 81.5,
83.3, 81.8, 80.6, 83, 82.9, and 81.9, with a mean of 82.1. Estimated
planetary A indices were 8, 7, 4, 5, 3, 3, and 3, with a mean of
4.7. Middle latitude A index was 6, 4, 3, 3, 2, 2, and 3, with a
mean of 3.3.
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