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ARRL Propagation Bulletin ARLP031 (2022)

ARLP031 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 31  ARLP031
From Tad Cook, K7RA
Seattle, WA  August 5, 2022
To all radio amateurs 

ARLP031 Propagation de K7RA

Solar activity continued to decline this week, with average daily
sunspot number dropping from 91.1 to 36.6 and average solar flux at
95.7, down from 107.6 the week prior.

Thursday's sunspot number was above the average for the previous
seven days at 52.  Solar flux on Thursday was above the previous
seven day average at 108.8.  The 2300 UTC flux was 111.3.

We've not seen lower values since mid-April in bulletin ARLP015 with
average sunspot number at 34.4, and the end of February in ARLP008
with average solar flux at 95.4.

To track solar cycle 25 progress, I like to compare current averages
against the same numbers from last year.  In the 2021 version of
ARLP031, average daily sunspot numbers were 33.1 (lower by 3.5 from
this week's report), and average solar flux was 83, down 12.7 from
the current average.

The lower activity was quite noticeable over the past week on 10 and
12 meters, but there must still be some daily sporadic-E, from what
I've seen on an email list devoted to 10 meter propagation beacons.
I have one myself, K7RA/B transmitting CW from CN87uq on 28.2833

The outlook from the USAF space weather group shows a meager
forecast for solar flux, this one from forecasters Hoseth and
Strandness on Thursday.

The latest forecast is a bit more optimistic than the Wednesday
version, with solar flux at 112 instead of 100 for the next few

Predicted solar flux is 112 on August 5 to 7, 110 on August 8 and 9,
112 on August 10, 114 on August 11 and 12, 98 on August 13 and 14,
100 on August 15 and 16, 98 on August 17 and 18, then 96, 96 and 98
on August 19 to 21, 96 again on August 22 and 23, 92 on August 24 to
28, 90 and 92 on August 29 and 30, 94 on August 31 through September
1, 96 on September 2 and 3, then 98 on September 4 to 10, and 100 on
September 11 and 12.

Predicted planetary A index 5 on August 5, 8 on August 6 and 7, then
5, 14, 12, 18 and 12 on August 8 to 12, 5 on August 13 to 16, then
22 on August 17, 15 on August 18 and 19, 8 on August 20 and 21, 5 on
August 22 to 25, then 10 and 12 on August 26 and 27, 5 on August 28
and 29, then 12 and 10 on August 30 and 31, 5 on September 1 to 6, 8
on September 7 to 8, and 5 on September 9 to 12.

OK1HH wrote:

"Throughout the period, solar activity was low, the Earth's magnetic
field quiet to unsettled.  Shortwave propagation conditions were
average to slightly below average.

An interesting phenomenon for observers may have been a giant solar
prominence - a loop of plasma on the sun's eastern limb.

But even more interesting was the report of a farside sunspot.  So
big it is changing the way the sun vibrates.  Helioseismic maps
reveal its acoustic echo not far behind the sun's southeastern limb!
The sunspot will turn to face Earth a few days from now."

Space Weather Woman Dr. Tamitha Skov, WX6SWW put out a new forecast
on July 29.

Recently Dr. Skov sent this out (I edited) to her Patreon

"This week the Sun is a mixed bag of active regions, coronal holes
and solar eye candy.  Although we aren't expecting any strong
storming at Earth, we do have a big-flare player in view and are
expecting some fast solar wind over the next few days (and then
again sporadically next week).  This might give aurora photographers
at high latitudes a brief show, but it likely wont be much, if any
better than the weak shows we got this past week.

Solar flux is finally back into the triple digits, which means
decent radio propagation again on Earth's day side and along with
the reasonably low risk for radio blackouts, amateur radio operators
as well as GPS users should enjoy better than average signal
reception (and transmission)."

I like to watch this link to see what might be coming over the next
few days on our Sun:

On Thursday night over on the left I am seeing lots of white
splotches, perhaps indicating areas of magnetic complexity and maybe
sunspots arriving soon.  The horizon is at -90 degrees.

Although the STEREO mission has survived way past the initial design
life, one of the probes has been gone for a few years, leaving us a
very limited view of the sun.

I would love to see a replacement probe, which I have heard might
cost twenty-million dollars.  Or perhaps a brand new advanced
design?  Perhaps one of our domestic billionaires fascinated by
space flight could make this happen.

Newsweek has solar news:

Large sunspot emerging:


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 July 28 through August 3, 2022 were 50, 40, 27,
39, 32, 31, and 37, with a mean of 36.6.  10.7 cm flux was 93, 90.8,
94.3, 95.4, 97.8, 98.8, and 99.9, with a mean of 95.7.  Estimated
planetary A indices were 7, 4, 7, 11, 8, 9, and 8, with a mean of
7.7.  Middle latitude A index was 9, 6, 8, 12, 8, 10, and 7, with a
mean of 8.6.


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