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ARRL Propagation Bulletin ARLP039 (2017)

ARLP039 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 39  ARLP039
From Tad Cook, K7RA
Seattle, WA  September 29, 2017
To all radio amateurs 

ARLP039 Propagation de K7RA

The past week was a good one for HF propagation. Average daily
sunspot numbers doubled from the previous week, rising from 13.6 to
27, while average daily solar flux rose from 72.6 to 84.3. Average
daily geomagnetic numbers were lower, with average planetary A index
declining from 21.1 to 9.9 and average daily mid-latitude A index
from 17.1 to 7.6.

Last Friday was the autumnal equinox, so we should see a seasonal
improvement in HF conditions.

Predicted solar flux is 91 on September 29 to October 1, 89 on
October 2 to 5, 90 on October 6 and 7, then 85, 76, 75, 74 and 73 on
October 8 to 12, 72 on October 13 to 15, then 71, 74, 73, 78, 80, 87
and 90 on October 16 to 22, 95 on October 23 to November 2, then 90,
85, 76, 75, 74 and 73 on November 3 to 8 and 72 on November 9 to 11.

Predicted planetary A index is 28, 18, 14, 12 and 8 on September 29
to October 3, 5 on October 4 to 10, 25 on October 11 to 13, then 20
and 15 on October 14 and 15, 8 on October 16 and 17, 5 on October 18
to 21, then 16, 8, 20, 25, 20, 10 and 8 on October 22 to 28, 5 on
October 29 through November 6, 25 on November 7 to 9, then 20, 15
and 8 on November 10 to 12.

"Geomagnetic activity forecast for the period September 29 to
October 25, 2017 from OK1HH.

Geomagnetic field will be:
Quiet on October 6, 23
Mostly quiet on October 5
Quiet to unsettled October 3, 10, 16 to 21
Quiet to active on September 29 and 30, October 2, 4, 7 and 8, 11,
14 and 15, 22, 24
Active to disturbed on October 1, 9, 12 and 13, 25

Increases of solar wind, mostly from coronal holes, are expected on
September 29 (-30), October (1, 3, 6,) 11 to 16, (17 and 18, 21 and
22, 24,) 25

- New activity on the Sun can dramatically change real development,
which has been happening more often lately.
- Parenthesis means lower probability of activity enhancement and/or
lower reliability of prediction.

F. K. Janda, OK1HH
Czech Propagation Interested Group
OK1HH compiling weekly forecasts since January 1978"

Dr. Tamitha Skov, the Space Weather Woman, has a new video:

Recent sunspots:

Looks like we survived the end of the world again last Saturday, as
a new predicted Armageddon failed to commence. From Phil Plait of
Bad Astronomy:

Of course this report is dated before the September 23 apocalypse,
and doesn't actually report afterward that it didn't happen, but my
world seems intact and I am still here. Are you?

Bob Kupps, HS0ZIA of Chiang Mai Province in Thailand reported on
September 25, "Propagation on 15m was much better than the numbers
might suggest - worked 5T5OK, 9J2BO and A25SP on CW all 2 to 3 hours
after sunset on Sep 25. Heard PY1VOY calling the A2 with very strong
signals at 1400Z - 3 hours after sunset."

Be sure to check Bob's page on to see his fabulous location
and antennas.

Rich Zwirko, K1HTV in Virginia reported on September 25, about his
adventures with weak signals via the FT-8 mode. But first, a review:

From K1HTV, "On Sunday September 24 propagation on the 15 meter band
was very good to Europe, the Middle East and Africa and the 21.074
MHz FT8 frequency was packed. The next day, September 25 around 2200
UTC, while listening to 7.074 MHz, the 40 meter FT8 frequency, the
band seemed to be in pretty good shape with many European stations
being decoded. Running 75 Watts and a wire antenna on 40M, I managed
to work VK6RZ and VK7AP both via the long path.

Switching to 20 meters, as European FT8 stations started to fade out
around 0000Z, the start of the September 26 UTC day, the band
started to go long. The SFI was 90 and the 'K' index was 0. After
working VK6YM via the long path (SE), I moved the beam to the north
in hopes that I'd copy some Asian stations over the northern polar

I wasn't disappointed. Over the next three hours, using the new FT8
digital mode and running 75 Watts to a triband Yagi I worked 16
stations in Asia. 10 stations were in Japan, 2 in Asiatic Russia, 2
in Kazakhstan and HS5SRH in Thailand. But the best DX of the evening
was 9N1AA in Nepal for my FT8 DXCC country 144. The new FT8 mode
has caught on worldwide in a big way. It is not unusual, during peak
hours to simultaneously decode between 20 and 30 stations during
each 15 second sequence, many of them -20 dB or weaker on the
approximately 2 KHz AWGN (Additive white Gaussian noise) channel.

The use of FT8 has resulted in the realization that despite what
appears to be poor propagation, many DX contacts can still be made
on the HF bands."

On September 28, K1HTV reported:

"While I'm at it, I thought that you would be interested to know that
in the early hours of September 26 the over the pole conditions to
Asia were great.

I was hearing Japan stations until almost local midnight here at my
Virginia QTH. 40 meter conditions at local dawn were good enough to
work a few VK stations. I spent the early to mid-afternoon working
FT8 stations in Europe, western Africa and South America, and later
working 5W0RA in Samoa and a VK2 station before the band closed.

By evening and the start of UTC Sept 27 the polar route to Asia was
still good enough to work four stations in Japan, but unlike the
previous day, the band shut down hours earlier as conditions started
to deteriorate.  During the daylight hours of September 27, 20M
conditions were pretty good to Europe.

But by later afternoon, with the K Index climbing up to 7, the
northern routes started to suffer.  But on the positive side, while
the K Index was 7, I gave 60 meters a try and was happy to work
5T5OK (Mauritania) on CW.

Using the FT8 digital mode, a number of European stations were
worked as well as XT2AT (Burkina-Faso), which was another new FT8
DXCC country. This morning (September 28), with the K index still
high, I got on 40M and was pleasantly surprised when on FT8 I copied
4S7AB. After only a few calls, the Sri Lanka station was in the
K1HTV log for FT8 country 147."

Rich worked 147 countries with this new weak signal mode in a short
period of time, using low power.

For more information concerning radio propagation, see 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

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 21 to 27, 2017 were 22, 22, 12, 22,
36, 40, and 35, with a mean of 27.  10.7 cm flux was 73, 77.5, 81.2,
86.9, 89.9, 90.7, and 91, with a mean of 84.3. Estimated planetary A
indices were 7, 5, 5, 6, 5, 4, and 37, with a mean of 9.9. Estimated
mid-latitude A indices were 7, 5, 4, 5, 5, 3, and 24, with a mean of


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