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ARRL Propagation Bulletin ARLP042 (2020)

ARLP042 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 42  ARLP042
From Tad Cook, K7RA
Seattle, WA  October 16, 2020
To all radio amateurs 

ARLP042 Propagation de K7RA

Sunspots returned for a few days, on October 9-12, with sunspot
numbers of 24, 26, 15 and 15, respectively. No sunspot appeared on
the next day, but late on Wednesday reported a new
emerging Solar Cycle 25 spot on our Sun's southeastern limb, and a
daily sunspot number of 12. NOAA Space Environment Center did not
report this, instead reporting the sunspot number at 0.

But the next day the record was corrected and NOAA reported sunspot
numbers of 12 and 14 on October 14-15.

Average daily sunspot number increased from 0 to 13.1, while average
daily solar flux went from 71.8 to 73.1.

Geomagnetic indicators were lower, with planetary A index dropping
from 7.1 to 2.7 and middle latitude A index from 6 to 1.9.
Prior to October 9 there were no sunspots for two weeks, and at that
time a sunspot number of 13 on September 23 and 11 on September 25.

Predicted solar flux for the next 45 days is 74 on October 16-17, 72
on October 18-31, 70 on November 1-7, 73 on November 8-10, then 72,
71 and 71 on November 11-13, 70 on November 14-23, 72 on November
24-27 and 73 on November 28-29.

Predicted planetary A index is 5 on October 16-19, then 10 on
October 20, 8 on October 21-23, then 16, 38 and 38 on October 24-26,
then 26, 15 and 10 on October 27-29, 5 on October 30 through
November 6, 10 on November 7, 5 on November 8-15, then 10, 15 and 18
on November 16-18, 20 on November 19-20, then 24, 14 and 10 on
November 21-23, 8 on November 24-25, and 5 on November 26-29.

From OK1HH, this report:

"Geomagnetic field will be,
quiet on: October 16, November 5-7, 10-13
quiet to unsettled on: October 17, 31, November 3, 14-16
quiet to active on: October (18,) 19-20, 28-29, (30,) November (1, 4)
unsettled to active: October 22, (24,) 27, November 2, 8 (-9)
active to disturbed: October (21, 23,) 25-26
"Solar wind will intensify on: October (20-21,) 22, (23-25,) 26-29,
(30,) 31, November (2-3,) 4-5, (9-11).
"Parenthesis means lower probability of activity enhancement."

Do you think the recent (or current) solar minimum is lasting a
little too long? Check this contrarian view:

Note the link toward the bottom of
the page. It shows sunspot records and predictions from 1730 til

Don't ask me to explain the numbers or how they were derived.

Also, perhaps someone can help this programmer on Stack Overflow
with his Python program for performing linear regression with a
sunspot database:

On Thursday I was listening to the local Puget Sound Repeater Group
machine on 146.96 MHz, and heard a couple of stations talking about
gray line long path propagation on 40 meters.

Dean Holtan, N7XS of Camano Island, Washington wrote, after I

"On Wednesday October 14 at 1530 UTC I heard K6MYC and company
working ZS6 stations. I also heard a station in the Netherlands,
PA1A I believe. He was very loud along with the ZS6 stations, S9
plus on the long path.

"I was listening on my SDRplay RSPduo and a 160 meter loop at 100
feet. If I had gotten out of bed and went down to the shack I could
have worked them. Thursday October 15, 20 meters was nicely open
into Europe. KW7Y was working many G stations and EA short path at
1630 UTC. The above was all on phone.

"Last week on October 10 starting at 0130 UTC when I was on
vacation, on 20 meters at our sunset I worked UN7JX and VU2MB along
with many others in Asiatic Russia. I was called by a station in
Lebanon but that was unsuccessful all on FT8 running 500 watts and
my 160 meter loop at 100 feet from Camano Island Washington."

Also in the conversation (linking via internet from Kitchener,
Ontario) was Doug Behl, VE3XDB. Later, Doug wrote:

"Many amateurs today complain about propagation. Conditions haven't
been great for several years, although there is some glimmer of hope
that things may be getting better. Those experiencing the most
frustration seem to be the sideband operators. I have had some
success over the past few years, using a couple of principles:

"1. Use a mode that does better in poor conditions. These days,
everyone jumps to 'FT8,' which is a fantastic, low power mode that
does very well in poor conditions. However, I prefer a mode that is
more 'chatty,' creating a more traditional QSO experience. CW and
PSK31 are both very good modes for effective contact when conditions
are poor, and may provide an opportunity to get to know the contact
a bit better.

"2. Work the gray line. Grayline propagation occurs at daybreak or
at dusk. It is very interesting because it occurs at a very
particular time of day, opens up very quickly, and then, when time
is up, it just disappears! Here is an short, interesting article on
the science and experience of gray line propagation:

" ."

"Following the above two principles, I have worked western and
eastern Europe, the Caribbean and South America, as well as Oceania
and Southeast Asia over the past few months, My modest station is
made up of a a short, inverted-L antenna and an old Kenwood
transceiver, usually running about 20 watts, and never more than 40
watts. Best results have been achieved on 20, 30 and 40 meters.

"To work the world when conditions are poor, I encourage others to
try CW and PSK31, especially at dawn or at dusk. You may be
surprised by the results achieved using a modest station. We need
more operators in both of these modes!"

Ken Brown, N4SO wrote:

"Evidence pointed to a very good propagation path to Asiatic Russia,
Japan, and to China on Saturday evening.

"From October 10, 2330Z UA0, and first BV, 21.074 MHZ FT8 mode.

"I first noticed UA0CA calling CQ from Asiatic Russia. This is a
rarity to see a UA0 on the screen and so far I have never completed
a contact. I have also never completed a contact with China until
Saturday evening.

"Calling UA0CA from my station was noticed by BV1EK, China, and he
called me, and was able to complete a contact. At this same time
period, completed contacts with JA1FGX, JQ1CIV, and JG1SRB.

"A contact with UA0CA or with UA0ZK was not made, but I can
appreciate the distance is roughly 5000 miles away. I will try again
on Sunday.

"(Distance to UA0ZK, for example, is 5391 miles.)"

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

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 October 8 through 14, 2020 were 0, 24, 26, 15,
15, 0, and 12, with a mean of 13.1. 10.7 cm flux was 71.6, 73.1,
73.6, 72.9, 73.8, 72.3, and 74.5, with a mean of 73.1. Estimated
planetary A indices were 3, 2, 2, 3, 4, 3, and 2, with a mean of
2.7. Middle latitude A index was 2, 1, 2, 2, 3, 3, and 0, with a
mean of 1.9.


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