This week the average daily sunspot number moved up from 66.9 for
the September 10-16 period, to 73 for the next seven days. Average
daily solar flux changed from 97.3 to 106.7. There was one new
sunspot group on September 20, two more on September 22, and another
new one on September 23.
At 0005 UTC on September 20 the Australian Space Forecast Centre
issued a geomagnetic disturbance warning for September 20 and 21 due
to a coronal mass ejection. Sure enough, at the end of the day on
September 20 the planetary A index hit 43, which indicates possible
aurora and a high level of absorption for HF signals. The college A
index (Fairbanks, Alaska) reached 73.
Spaceweather.com reported the CME impact hit Earth a day earlier
A second similar warning was issued at 2255 UTC on September 21 for
the following day, but the CME missed, and had no impact. Conditions
were quiet and stable.
NOAA has had some trouble of late getting the daily 45 day forecast
of solar flux and planetary A index from the Air Force. This is
because of some issues with moving to new servers. Thanks to Robert
Steenburgh, AD0IU who is a space scientist at NOAA for keeping us up
to date with missing data.
If you check ftp://ftp.swpc.noaa.gov/pub/
forecasts and ever have a problem with the links, you can check here
for the latest numbers for the current day only:
The latest forecast (from September 24) has predicted solar flux at
110 on September 25-26, 105 on September 27, 110 on September 28,
105 on September 29-30, 100 on October 1, 95 on October 2-5, 100 on
October 6-7, 105 on October 8-11, 100 on October 12, 95 on October
13-15, 90 on October 16-17, and 110 on October 18-20.
Predicted planetary A index is 15 on September 25-26, then 8 on
September 27-30, 20 on October 1, 15 on October 2-3, then 45, 25 and
18 on October 4-6, 12, 50 and 15 on October 7-9, and 12 on October
In addition to the high A index predictions for October 4 and 8 (45
and 50), 45 is predicted again for October 31 and 50 again on
Petr Kolman, OK1MGW of the Czech Propagation Interest Group sends
along his weekly forecast for geomagnetic activity: Quiet to
unsettled conditions on September 25, quiet on September 26-28,
mostly quiet September 29, quiet to unsettled September 30, quiet to
active October 1-3, quiet to unsettled October 4-6, active to
disturbed October 7-8, quiet to unsettled October 9-10, quiet to
active October 11-14, quiet to unsettled October 15, quiet to active
October 16-17, mostly quiet October 18-20, and quiet to unsettled on
Petr also expects increases in solar wind on October 1-3, 7-10, and
The Autumnal Equinox was on Wednesday, September 23 at 0822 UTC.
This is when the Northern Hemisphere moved into Fall, and the
Southern Hemisphere saw Spring. Right now, close to the equinox is a
good time for HF propagation, particularly between the Northern and
Thanks to Frank Donovan, W3LPL for alerting us to a new scientific
paper in the Astrophysical Journal, "The Recent Rejuvenation of the
Sun's Large-Scale Magnetic Field: A Clue For Understanding Past and
Future Sunspot Cycles" showing evidence that perhaps Solar Cycle 25
won't be weaker than the current Solar Cycle 24.
The paper begins: "The quiet nature of Sunspot Cycle 24 was
disrupted during the second half of 2014 when the Sun's large-scale
field underwent a sudden rejuvenation: the solar mean field reached
its highest value since 1991, the interplanetary field strength
doubled, and galactic cosmic rays showed their strongest 27-day
modulation since neutron-monitor observations began in 1957; in the
outer corona, the large increase of field strength was reflected by
unprecedentedly large numbers of coronal loops collapsing inward
along the heliospheric current sheet."
Jon Pollock, K0ZN of DeSoto, Kansas reports in an email titled
"Excellent 10 MHz Propagation." He writes, "Sunday night (9/20/15)
from 0300 to about 0330 UTC, 3B8CF (Mauritius Island, in the Indian
Ocean) was quite strong into Eastern Kansas. That is a 10,400 mile
path from my QTH. Obviously, I have no way of proving it, but due to
the relative lack of QSB on his signal, I suspect ionospheric
ducting; not an uncommon event on 10 MHz from what I have seen. 30
meters was extremely quiet that evening after about 0245 which
probably led people to think it was 'dead,' but I have heard this
many times before. I could hear absolutely no state side stations
east of here but I could hear 3B8CF responding to them giving good
reports, again confirming how long the skip was. When the 30 meter
band gets very quiet at night, it is usually very long skip to some
part of the world."
Check out K0ZN's description of his antenna system on his QRZ.com
Dick Bingham, W7WKR of Stehekin, Washington is excited about 160
meters and WSPR mode. He sent this report a week ago:
"160-meters seems to be perking up now. I was running 5-watts in
WSPR-mode last week and had a nice report of being 'heard' by VK2KRR
down under. Not bad for 5-watts.
"I will be trying K1JT's 'JT9' software tonight. It is supposedly
better on MF and 160-meters, by several dB, than WSPR and the 'JT65'
modes other 160-meter folks are using.
"If you have not already tried some of the K1JT digital modes, I
would suggest you at least try WSPR for a few days. I was very
impressed after my first attempts using it and am now 'sold' on the
"WSPR is a great way to see where you are being 'heard', and how
well, in the days before a contest.
"The antenna I use on 160-meters is what is called a 'Half-Square.'
It is a great antenna if you have tall trees or towers available. My
H-S is supported at about 90-feet at both ends of a L/2 top-wire
phasing section (basically a non-radiator.) Two L/4 end wires
connected to the top wire ends slope away toward 10-feet above
ground where one end is fed using a Hi-Z tuner. My H-S's figure-8
pattern basically radiates E/W so VK-Land is on the great-circle
path and probably the reason I get into that part of the world,
running 5-watts, so well.
"I have found this antenna highly desirable because it seems to work
well without a 'ground' any more significant than an eight-foot
ground rod pounded into my gravel/sand valley bottom where I live
here at Stehekin. 100-watts has gotten me into England, Germany and
SM-land using CW and the H-S.
"You will be AMAZED at what you hear and who hears YOU after you
load and run the WSPR software. Look for the WSPR4.00r4171.exe
software as opposed to earlier versions.
"Those of us who are part of the ARRL 600-meter experiment
(WD2XSH-#) find WSPR to be a useful tool for our propagation studies
"The most modest of antennas will perform well for you. Once you run
for a week or so, make some improvements in your antenna and then
run another week to evaluate your 'improvements.' Barring markedly
different prop-conditions, you should be able see differences
"Run 1-watt and be ready to be surprised to see how many stations
will copy you!"
Thanks, Dick. Great report!
Here are some details on half-square antennas:
Here is information on WSPR:
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For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
numbers used in this bulletin, see
propagation bulletins is at
information and tutorials on propagation are at http://k9la.us/.
My own archives of the NOAA/USAF daily 45 day forecast for solar
flux and planetary A index are in downloadable spreadsheet format at
http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .
Click on "Download this file" to download the archive and ignore the
security warning about file format. Pop-up blockers may suppress
download. I've had better luck with Firefox than Internet Explorer.
Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.
Sunspot numbers for September 17 through 23 were 72, 62, 61, 74, 68,
79, and 95, with a mean of 73. 10.7 cm flux was 106.8, 102.8, 105.7,
110.4, 103.4, 107, and 110.7, with a mean of 106.7. Estimated
planetary A indices were 12, 13, 16, 43, 9, 10, and 14, with a mean
of 16.7. Estimated mid-latitude A indices were 12, 11, 12, 32, 9, 8,
and 13, with a mean of 13.9.
ARRL Web site - firstname.lastname@example.org
QST de W1AW
Propagation Forecast Bulletin 39 ARLP039
From Tad Cook, K7RA
Seattle, WA September 25, 2015