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ARRL Propagation Bulletin ARLP040 (2016)

ARLP040 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 40  ARLP040
From Tad Cook, K7RA
Seattle, WA  September 30, 2016
To all radio amateurs 

ARLP040 Propagation de K7RA

Australia's Space Weather Services issued a geomagnetic warning at
0022 UTC on September 29:

"The geomagnetic conditions are expected to vary between active
levels to major storms for the next three days. This is because the
solar winds are expected to be in excess of 600 km/s associated with
a very large positive polarity coronal hole. The storm intensities
are expected to be slightly stronger than that observed in the
previous two solar rotations (previous rotation Ap was 32)
associated with this coronal hole because the earth-sun coupling
efficiency is highest during the equinox periods. Thus there is
chance that aurora may be visible on the local nights of 29
September from Tasmania and some parts of Victoria, Australia.


29 Sep:  Minor Storm 
30 Sep:  Minor Storm 
01 Oct:  Active to Minor Storm"

This week's (September 22-28) average daily sunspot numbers and
solar flux changed little from the previous seven days. Average
daily sunspot numbers changed from 29.9 to 29.7, and average daily
solar flux declined just two points from 83.4 to 81.4. Average
planetary A index was much higher, changing from 8.9 to 19.7, and
average mid-latitude A index changed from 7.6 to 12.3.

Projected solar flux for the near term is 81 and 78 on September 30
through October 1, 80 on October 2-3, 82 and 85 on October 4-5, 90
on October 6-14, 95 on October 15-18, 90 on October 19-21, 85 on
October 22-27, 80 on October 28-31, 85 on November 1-3, and 90 on
November 4-10.

Predicted planetary A index is 38, 30, 20, 14, 12, 10 and 6 on
September 30 through October 6, 5 on October 7-14, then 8, 10, 20,
10, on October 15-18, 5 on October 19-22, then 18 and 12 on October
23-24, 35 on October 25-27, then 25, 20, 16, 10 and 8 on October 28
through November 1, 5 on November 2-10, and 8 on November 11.

Here is the weekly geomagnetic forecast from F.K. Janda, OK1HH of
the Czech Propagation Interest Group:

"Geomagnetic activity forecast for the period September 30-October
26, 2016

"Geomagnetic field will be:
Quiet on October 9-10, 13,
Mostly quiet on October 7, 11, 14, 20,
Quiet to unsettled on October 5-6, 8, 15-16, 19, 21,
Quiet to active on October 1-3, 5, 12, 17-18, 23-24
Active to disturbed on September 30, October 4, 22, 25-26

"Increases of solar wind from coronal holes are expected on
September 30, October 1-3 and 15-17."

On September 24 Jim McLelland WA6QBU of Santa Rosa, California sent

"Just a quick note about DX. I noted last night that conditions were
quiet on 20 meters, which is unusual for me on the West Coast, with
sunspots at 30, SFU at 85 and a quiet Sun. Therefore, moving to 40
meters, I found the band open to South Africa and worked Bill,
ZS6CCY who was 10 dB over S9.  Keep up the good work."

Then on September 30 he wrote, "Mr. Cook, One more thing - 10 meters
was open to Hawaii (SSB) from the West Coast last weekend and again
Tuesday early evening."

Mark Ammann, KM0A had some comments about VHF propagation enhanced
by aurora in a September 28 email:

"I always enjoy reading your propagation updates via ARRL email
member list, and especially the personalized experiences you
include. Having been on 2 meters and 6 meters for almost 40 years,
aurora is always fascinating yet rare, more so on 2m since it
provides DX distances normally unattainable on that band, save for
extended tropo or the rare E-skip opening. I wanted to add to your
comments re Jon N0JK's aurora during the 2m sprint.

"2 meter aurora CW signals, in my opinion, are not 'buzzy' or
'distorted,' but actually very easy to copy unless the signals are
extremely weak. They sound more like a hollow whisper. Sound clips
are below of actual aurora signals.

"As for aurora on 6 meter SSB, signals are distorted somewhat but
easy to copy if one speaks slowly. As for 2m SSB, signals are much
distorted and very difficult to comprehend. Sounds almost like the
person is gargling rocks!

"Keep up the good work!"

Mark included links with audio samples of CW and SSB signals
received via auroral propagation.

Ted Leaf, K6HI of Kona, Hawaii sent this about using NVIS antennas
on 40 meters:

"If of interest, you may want to put this out. We have nets, all
year across the Hawaiian Island chain at 4pm/0200 UTC on 40M, with
our low antennas barefoot, it is NVIS out to 200 miles. Sometimes
very noisy, but usually work all stations."

NVIS is Near Vertical Incidence Skywave propagation. Here are some

Jon Jones, N0JK of Lawrence, Kansas sent this report early Friday
morning, September 30:

"With the Fall Equinox and geomagnetic storms this week due to a
fast moving stream of solar wind, 10 meters has come alive on north
- south paths. The last couple of days Uli, VP6AH has had a loud
signal on 10 meters to North America. He is running just 100 watts
and a dipole antenna and was over S-9 on my mobile Sept. 27 about
2015z.  H44GC, VK9NZ, FY5KE, VP8LP and others have also been active
on 10."

And finally, a story about a geomagnetic disturbance in 1941. Thanks
to WW1ME who forwarded this from the Southgate Amateur Radio News:

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 at For an explanation of the
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 22 through 28 were 30, 49, 47, 18, 23,
21, and 20, with a mean of 29.7. 10.7 cm flux was 85.1, 85.5, 84.9,
84.6, 86.8, 85.6, and 84.4, with a mean of 81.4. Estimated planetary
A indices were 4, 4, 5, 23, 22, 38, and 42, with a mean of 19.7.
Estimated mid-latitude A indices were 4, 3, 4, 12, 18, 21, and 24,
with a mean of 12.3.


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