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ARRL Propagation Bulletin ARLP049 (2021)

ARLP049 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 49  ARLP049
From Tad Cook, K7RA
Seattle, WA  December 3, 2021
To all radio amateurs 

ARLP049 Propagation de K7RA

Solar activity was up this week. Average daily sunspot number
increased from 26.9 to 46.1, and average daily solar flux was up
10.8 points to 90.9. Geomagnetic indicators were a little higher.
Average daily planetary A index increased from 7.9 to 8.7, and
average daily middle latitude A index from 5.4 to 6.3.

I like looking for openings on the 10 meter band, and continue to be
surprised by how often I hear nothing on 10 meters (when probing
with FT8 and pskreporter) but find plentiful openings on 12 meters,
indicating the MUF is somewhere between 10 and 12 meters. To help 10
meter observers, I have a CW propagation beacon on 28.2833 MHz,
K7RA/B in Seattle. It runs about ten watts into a half wave dipole
at a modest height.

Two new sunspot groups emerged on November 26, one on November 28,
and two more on November 30.

On December 1, announced a geomagnetic storm watch:
"Minor geomagnetic storms are possible on December 3 when a CME
might sideswipe Earth's magnetic field. The storm cloud was hurled
into space on November 29 by an erupting filament of magnetism in
the Sun's southern hemisphere. According to NOAA computer models,
the bulk of the CME should sail south of our planet with a near miss
just as likely as a glancing blow."

At 2340 UTC on December 2, the Australian Space Forecast Centre
issued a Geomagnetic Disturbance Warning: "The effects of a coronal
hole wind stream and coronal mass ejection are expected to increase
geomagnetic activity on 03 December.  Conditions are likely to be
initially quiet with activity increasing. Active to minor storm
levels are expected."

Predicted solar flux for the next month has flux values peaking at
94 on December 27-28. The forecast sees values of 86 on December 3,
84 on December 4-5, 82 on December 6, 80 on December 7-10,  82 on
December 11-12, 80 on December 13-14, 85 on December 15-21, 82 and
80 on December 22-23, 78 on December 24-25, 92 on December 26, 94 on
December 27-28, 88 on December 29, 2021 through January 1, 2022,
then 85, 82 and 80 on January 2-4, 82 on January 5-8, and 80 on
January 9-10.

Predicted planetary A index is 12, 14, 10 and 12 on December 3-6, 8
on December 7-8, 5 on December 9-11, then 8, 12 and 10 on December
12-14, 5 on December 15-16, then 8 and 10 on December 17-18, 5 on
December 19-25, 8 on December 26, 5 on December 27-29, 10 on
December 30-31, 8 on January 1, 5 on January 2-7, then 8, 12, and 10
on January 8-10.

AA6XE wrote:

"We now stand at exactly 2 years since the Cycle 24/25 Minimum was
recorded and the most notable attribute of Solar Cycle 25 is its
slow climb out. We have seen bursts of activity from the Sun where
numerous Active Regions pop up with only a handful actually
developing into numbered Sunspot Groups. The bulk of the new regions
that form quickly decay away. As it stands right now Solar Cycle 25
activity is running a little bit ahead of the same point in Solar
Cycle 24. Does this point to a weak Solar Cycle much like we
experienced with Solar Cycle 24?

"It's still too early to say. The first couple of years in any Solar
Cycle are never easy to take and Solar Cycle 25 is proving itself no
exception. We await 'the breakout' when Solar Activity ramps up

He continued: "A dramatic run-up in Solar Flux over a period of a
few days has little influence on increasing Ionospheric MUF. What
does have an effect on the Ionospheric MUF is an increase in the
Monthly Solar Flux Average and more significantly an increase of the
90 Day mean Solar Flux Reading. The dramatic and unanticipated spike
in sunspot activity we saw a year ago, November 2020, temporarily
goosed the 90 Day Solar Flux Average which had been running in the
low 70s at the time, boosting it into the Low 80s in the ensuing 60

"It became quickly apparent the November 2020 event was an outlier
and the 90 Day Solar Flux subsequently slipped back to the Mid 70s
by mid-April 2021. Since that time the 90 Day Solar Flux Average has
been rising steadily albeit slowly. As long as those figures
continue to steadily chug up hill MUF levels will continue to rise.
The 90 Day Solar Flux Average as it stands presently is in the Upper
80s. The 90 Day Solar Flux Mean will be in the low 90s by the end of
December if Solar Activity resumes the pace of growth we saw early
in the fall. The Solar Breakout predicted by folks at NCAR (National
Center for Atmospheric Research) has not materialized in time to
provide any sort of relief to the Winter Season Doldrums we normally

"On the  bright side this winter season is shaping up to be one of
the best we will see on 160 Meter DX in the last several years.
Solar Activity has picked up just enough to increase Ionization at
those frequencies with little or no increase in D-Layer Absorption
while the Planetary K Index has remained low."

On November 29, N0JK reported from Kansas:

"There was 6M sporadic-E on Thanksgiving.

"From Kansas I worked WB5TUF (EL29) and NE5U (rare grid EL19) around
0240 UTC November 25 on 50. 313 MHz FT8.

"N0LL (EM09) worked NR4J (EM60) at 1625 UTC on 6 Meter FT8 November

From OK1HH:

"Weekly commentary on phenomena in the Sun, in the magnetosphere and
in the ionosphere of the Earth.

"One week ago, I compiled my last weekly forecast of the Earth's
magnetic field activity. Primarily, my goal was to compile
predictions of changes in the ionospheric propagation of decameter
waves. Their first users were my friends - radio amateurs. But 45
years ago no one provided available predictions. That's why I
gradually learned to compile them myself. Today, actually applicable
predictions are available from several sources on a weekly and daily
basis, especially in the USA, Belgium, Australia, Russia and, to my
delight, also in the Czech Republic.

"In the meantime, I had long since reached retirement age and
planned to finally quit. But I was asked to try to continue, using
my experience. Therefore, from now I will try to write comments on
current and upcoming development. If this activity will be found as
useful and/or interesting, I will continue. And like 45 years ago,
it's an experiment. So here is my first attempt:

"Solar activity remains at current levels, and due to the location
of solar coronal holes near the central meridian, the influx of
faster solar winds can be expected to continue.

"The irregular daily course of changes in the ionosphere, to which
the relatively low or still declining solar activity will
contribute, should continue in the next five days or so.  In
addition, after the CME on November 29, it is still possible for the
plasma cloud to arrive late on December 2 or during December 3 - but
the probability is already low.

"After the expected slight increase in solar activity, I expect a
more regular course of ionosphere parameters in the second half of

"F. K. Janda, OK1HH
Email: ok1hh(at), ok1hh(at)

NASA's new feature starts today:

Sunspot rotation rate history:

Sunspot variations during their decay:

Dynamics of bright features:

A report from Dr. Tamitha Skov, WX6SWW, for December 1:

If you would like to make a comment or have a tip for our readers,
please email the author at, .

For more information concerning shortwave 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 November 25 through December 1, 2021 were 20,
52, 53, 53, 47, 61, and 37, with a mean of 46.1. 10.7 cm flux was
93.6, 92.3, 91.8, 92.2, 89.8, 90, and 86.4, with a mean of 90.9.
Estimated planetary A indices were 5, 4, 5, 9, 9, 11, and 18, with a
mean of 8.7. Middle latitude A index was 3, 3, 3, 7, 6, 8, and 14,
with a mean of 6.3.


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