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ARRL Propagation Bulletin ARLP051 (2022)

ARLP051 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 51  ARLP051
From Tad Cook, K7RA
Seattle, WA  December 23, 2022
To all radio amateurs 

ARLP051 Propagation de K7RA

I am writing this first draft of my penultimate bulletin of 2022,
about seven hours after the start of Winter Solstice in the Northern
Hemisphere, which was on Wednesday, December 21, 2022 at 2147 UTC.
It is very cold in Seattle, about 17 degrees F on the longest night
of the year.

Solar activity was down a bit from the previous week, although it
was one of those odd occasions when average daily sunspot numbers
and solar flux changed in opposite directions.

Average daily sunspot number declined from 136.9 to 124.1, while
solar flux rose from 150 to 153.8.

Two new sunspot groups emerged on December 17, one more on December
19, another on December 21, and two more on December 22.

Geomagnetic indicators were a bit lower, with average planetary A
index changing from 7.7 to 6.7, and middle latitude numbers from 6
to 5.1.

Due to missing data, I had to fudge one of the numbers, the December
16 middle latitude A index which I pegged at 7 by eyeballing trends.

Predicted solar flux appears to reach a short term peak of 160 on
January 4-7, 2023, which may repeat on the last day of January and
the first few days in February.

The forecast shows 130 on December 23-25, 135 on December 26–30,
138 on December 31, then 140, 150 and 155 on January 1-3, 2023, 160
on January 4-7, then 158, 156, 154, 154 and 152 on January 8-12, 150
on January 13-15, then 145, 130 and 120 on January 16-18, 118 on
January 19-20, then 120, 125 and 127 on January 21-23, 130 on
January 24-25, then 135, 138, 140, 150 and 155 on January 26, and
160 on January 31 through the first few days of February.

Predicted planetary A index is 8, 5 and 8 on December 23-25, 5 on
December 26-29, 10 and 12 on December 30-31, then 8, 5 and 18 on
January 1-3, 2023, 10 on January 4-5, then 8, 10 and 6 on January
6-8, 5 on January 9-14, then 12, 10 and 20 on January 15-17, then
12, 8, 5 and 18 on January 18-21, and 20 on January 22-24, then 12,
10, 12, 8 and 5 on January 25-29.

OK1HH writes:

"Over the past seven days, we observed up to seven sunspot groups on
the solar disk, three in succession had sizes and configurations
suggesting the possibility of an M-class flare.

"AR3165 fell behind the western limb on December 17, while we
observed AR3169 the same day. The largest AR3163 went over the limb
on December 22. Solar activity, both total and flare activity,
slowly decreased.

"A shock wave (probably the CME released by sunspot AR3165 last
week) hit Earth's magnetic field late on December 18, but a
geomagnetic storm did not develop, only a slight increase in
geomagnetic activity. This was repeated on December 21 and
especially the next day, when it was a recurrent disturbance,
repeated after about 27 days.

"Solar activity is likely to remain low until Christmas. The
situation may change next week, when one or more active sunspot
groups will appear on the eastern limb of the solar disk.

"Shortwave propagation was mostly above average with slightly
elevated MUF values. Diurnal variations were erratic. This pattern
will continue."

Jon, N0JK wrote:

"A strong sporadic-E opening on 50 MHz from Kansas to the Gulf Coast
Sunday December 18.

"I logged K3FM EM50, WA3GWK EM60, W5THT EM50, and N4UPX EM50 on
50.313 MHz FT8 around 1600 UTC with strong signals. My station was
100 watts and an attic dipole."

More big solar flare news:

Found this interesting resource in the ARRL Letter:

From Dr. Tony Phillips on cycles:

On Thursday using I made a 10 meter contact with
Ralph, VE3LOE. He sent me an email, which I have edited:

"About 2 years ago I was in touch with Scott McIntosh at the
National Center for Atmospheric Research in Boulder, CO, who made a
minority-opinion propagation forecast for Solar Cycle 25 which
suggests much higher solar activity than what his colleagues
predict. See 'Overlapping Magnetic Activity Cycles and the Sunspot
Number: Forecasting Sunspot Cycle 25 Amplitude' (text dated October

"The latest installment, entitled 'Deciphering Solar Magnetic
Activity: The (Solar) Hale Cycle Terminator of 2021,' which is at:


"I scanned this latter paper just now. Although I am a retired
engineer from the telecom sector with a PhD in statistical traffic
analysis of pre-Internet data networks, and understand the
statistical math used in these papers, I am not a propagation
expert. However, in the last publication, Figure 10 predicts a mean
SSN just under 200, higher than other expert predictions. This
present cycle has been interesting in its statistical variability.

"I am primarily a 10m enthusiast and use this band on a daily basis,
generally in the 1300-1700 UTC timeframe when the EU openings take
place.  For some of my other ham interests and operating conditions
you can visit my page."

K7RA notes - download this pdf:

A new report from Dr. Tamitha Skov, WX6SWW:

Send your tips, reports, observations, questions, and comments to

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service 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 15 through 21, 2022 were 140, 108, 139,
128, 132, 119, and 103, with a mean of 124.1. 10.7 cm flux was
165.9, 163.1, 154.6, 155,6, 152.4, 146.4, and 138.7, with a mean of
153.8. Estimated planetary A indices were 5, 9, 3, 4, 11, 6, and 9,
with a mean of 6.7. Middle latitude A index was 4, 7, 2, 2, 9, 5,
and 7, with a mean of 5.1.


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