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ARRL Propagation Bulletin ARLP037 (2017)

ARLP037 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 37  ARLP037
From Tad Cook, K7RA
Seattle, WA  September 15, 2017
To all radio amateurs 

ARLP037 Propagation de K7RA

At 0005 UTC on September 15 the Australian Space Weather Forecast
Centre issued a Geomagnetic Disturbance Warning.

"The previous geomagnetic warning is extended for two more days. The
high speed streams associated with the coronal hole is expected to
persist for a few days. If the Bz component of the IMF turned
strongly southward for prolonged periods, earth could experience
minor storm conditions. Otherwise, expect mostly unsettled to active
condition for the next two days (15 and 16 September).


15 September  Active
16 September  Active" 

Over the past reporting week (September 7-13) sunspot numbers and
solar flux were lower, while geomagnetic indicators were higher.

Average daily sunspot numbers declined from 87.3 to 45, and average
daily solar flux went from 114.1 to 97.6.

Average daily planetary A index increased from 18 to 27.3, and
average daily mid-latitude A index went from 16.7 to 18.3.

Predicted solar flux is 74 on September 15-21, then 90, 92, 95, 98,
105, 110, 115 and 120 on September 22-29, 125 on September 30 and
October 1, then 120, 115, 110, 100, 95, 90, 85, 83, 81 and 84 on
October 2-11, 83 on October 12-14, 84 on October 15, 85 on October
16-17, then 88, 90, 92, 95, 98, 105, 110, 115 and 120 on October
18-26, 125 on October 27-28 and 120 on October 29.

Predicted planetary A index is 28 on September 15-16, 26 on
September 17, 12 on September 18-21, 5 then 5, 8, 5, 8 and 5 on
September 22-26, 20 on September 27-29, then 18, 15, 12 and 8 on
September 30 through October 3, 5 on October 4-7, then 7 and 12 on
October 8-9, 30 on October 10-12, 20 and 10 on October 13-14, 5 on
October 15-16, then 8, 5, 5, 8, 5, 8 and 5 on October 17-23, 20 on
October 24-26, then and 18, 15 and 12 on October 27-29.

Geomagnetic activity forecast for the period September 15-October
11, 2017 from OK1HH:

"Geomagnetic field will be:
Quiet on September 23-24
Mostly quiet on September 20, 27
Quiet to unsettled September 19, 21-22, October 4, 6
Quiet to active on September 15, 17, 25-26, 30, October 1-3, 7-8, 10-11
Active to disturbed on September 16, 18, 28-29, October 5, 9

"Amplifications of the solar wind from coronal holes are expected on
September 15-19, 27-29, October (1,) 2-5, (8)

"Remark: - Parenthesis means lower probability of activity
enhancement and/or lower reliability of prediction.

"F.K. Janda, OK1HH Czech Propagation Interested Group"

Here are videos from September 7 by Dr. Tamitha Skov. The second one
is an hour-long program in which she answers viewer's questions
about recent activity. It contains lots of great information. I love
it when she tries to set the record straight about HAARP, that no,
it is not a tool for mind control or messing with the weather:

A Newsweek article about seven massive solar flares in seven days is
available at:

Chuck Zabriskie, KE5HPY of Houston, Texas reported on September 9:

"Thought one could add WSPR to the propagation aids discussed in
your latest report. With the high flux report, I put my homebrew 10m
WSPR rx on-line and happily recorded TI, CE, ZL and multiple VK
calls for the first time in a long while.  Of course those were
regular events a couple of years ago but now are rare enough to me
get excited to look at the logs.

"Thanks for all your efforts to keep the community well informed
about propagation."

On September, Jeff Hartley, N8II in Shepherdstown, West Virginia

"While it has been mostly bad, the very high absorption has settled
down at times to make for some interesting openings.

"I observed a total ionospheric blackout at 1703Z Sunday, followed
at 2030Z with some of the best conditions in the Worked All Europe
contest of the whole weekend from then until the end at 2400Z.
Northern and eastern EU were not workable however on either 20 or 40
except for Ukraine and southern Russia on 40M. Signals from Germany
to the west and south were loud on 20M in the 2100Z hour. I was
unable to work any EU at 2400Z Saturday, very depressed high
absorption conditions at that time, despite loud French signals on
20 in the 2300Z hour."

On September 14 Jeff wrote:

"It has been a roller coaster of conditions with some equatorial
paths enhanced in the past 9 or so days. The only time I heard Asia
during the AADX phone contest Labor Day weekend was Sunday around
0100Z and that was Kazakhstan. That weekend, I primarily operated
the CO QSO party Saturday and would say that 20 meters was poor a
couple of hours in the early afternoon, but otherwise in decent
shape to CO which is a good distance for us for single hop F2
despite a fairly high K index. 40 meter signals seemed down a bit
especially early evening, but some mobiles and K8TE operating
portable probably with a vertical and barefoot were easy copy by
2400Z (my local sunset was about 2335Z). Only W7RF who has a pretty
big station was heard on 80.

"The CW ops open contest started at 2000Z on 9/2 and there seemed to
be some Es into the W4/5 call areas; there were many loud signals
and western EU stations were workable without having to move my main
Yagi from the west. Later there also seemed to be some Es into the
Midwest allowing loud signals CO past when F2 would normally fade; I
was still working CO at 0139Z.

"Tuesday 9/5 was an above average day despite fairly high K index.
In the 1200Z hour on 20 SSB I worked ZS3Y in South Africa long path,
VK4FW/P in a park and VK6JDW Australia, and P29LL Papua New Guinea.
Then I checked 30 meters to find VK4FW/P about 10 dB louder than 20M
and also E51JHQ in the South Cook Is. with a good signal. At 1308Z I
tried  a CQ on 15 phone after hearing a fairly strong British
station on CW and F4BWX a yank living in Royan, France answered
saying I was the first USA station he had heard on 21300 during over
4 weeks of monitoring. He was a solid S5 here running only 100W to a
dipole. I went on starting at 1444Z to work several stations in
England and Germany on 15M CW and phone. The biggest EU surprise was
a good signal from Ivan, RA7A in Krasnodar, Russia (Black Sea area).

"Then I saw a spot from NC of James, 9V1YC in Singapore on 15M CW and
amazingly he was a solid S5-6 here and I went right into his log at
1534Z. I also heard a weak Indonesian station on 17M around 1300Z.
This was the best day of the week/past several months on 15M. After
that the flares and high absorption limited anything non-equatorial.

"On the 7th at 0045Z, I worked special anniversary calls XK150YT and
CI1AAA operating from Whitehorse, Yukon, Canada who was S9, but CQs
toward Asia were fruitless and no spots of Asians were noted. FK8IK,
New Caledonia had a good signal on 15CW at 0051Z. He was worked in
NA on 12 and 10M earlier.

"Since then conditions have been fairly poor. The Worked All Europe
contest was 9th-10th and was quite a challenge. The first good
opening I found on 20M was around 2300Z on Saturday evening, but I
was gone most of the day. Spanish and French stations were loud, but
no stations were loud enough to hear me on 40 due to disturbed
conditions. Sunday morning signals were poor on 20, but I did manage
QSOs with northern Sweden and the Aland Islands along with other EU
big guns. There was a fairly brief limited opening on 15M working
UA7K southern Russia at 1335Z and Spain, Slovenia, Croatia, and
Malta around 1445Z. There was a total blackout on all bands when I
checked at 1703Z with the X8 class flare, but by 2000Z signals from
Germany, Italy, the Balkans and closer were fairly normal and I was
able work the same areas on 40M in the 2300Z hour, but activity was
pretty low."

So in last week's bulletin ARLP036 we reported a remarkable increase
in solar activity. On the air, HF radio operators reported fantastic
conditions, at least in quieter periods between solar flares.

The average daily sunspot number was 87.3 reported in ARLP036. How
long since we have seen similar activity?

Last year in bulletin ARLP034 on August 19, 2016 the average sunspot
number reported was 73.9, and it was 86.6 in ARLP007 on February 12,
2016, but the last time we reported a higher average weekly sunspot
number than last week's bulletin was November 6, 2015 when it was

Looking back further in 2015 we saw these numbers:

120.9 40  Oct 2, 2015
112.4 33  Aug 14, 2015
104.5 32  Aug 7, 2015
112.4 24  Jun 12, 2015
146.9 20  May 15, 2015
120.9 17  Apr 24, 2015

The number after the average sunspot number on the left is the
propagation bulletin number for that year.

Perhaps we will see a return to this level of activity in 3-4 years,
after a projected minimum in 2019-2020, perhaps in 2021-2022.

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 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

Monthly propagation charts between four USA regions and twelve
overseas locations are at

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

Sunspot numbers for September 7-13, 2017 were 94, 89, 49, 38, 23,
11, and 11, with a mean of 45. 10.7 cm flux was 128.5, 116.8, 107.2,
100.2, 79.9, 75.5, and 75.1, with a mean of 97.6. Estimated
planetary A indices were 38, 96, 6, 7, 11, 18, and 15, with a mean
of 27.3. Estimated mid-latitude A indices were 23, 50, 6, 12, 8, 16,
and 13, with a mean of 18.3.


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