ARRL Propagation Bulletin ARLP025 (2011)

ARLP025 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7RA
Seattle, WA  June 24, 2011
To all radio amateurs 

ARLP025 Propagation de K7RA

Over the past week (June 16-22) the average daily sunspot number
rose nearly 20 points to 55, and average daily solar flux readings
increased by nearly 9 points to 98.6.  All geomagnetic indices
declined slightly.  These increases or decreases are relative to the
previous seven days, before June 16.

For the past month we've been looking nervously toward ARRL Field
Day, because a forecast from NOAA and USAF showed possibly unsettled
geomagnetic conditions on Friday, June 24, and continuing through
Field Day weekend.

The forecast has evolved from troubling to frightening, and back
again. Early in June the predicted planetary A index for June 24-26
was 18, 18 and 15. Then on June 7 it changed to 15, 15, and 10, a
little better. Then a week later things looked even more promising
on June 14 at 15, 10 and 5. But on June 17 it was revised upward, to
30, 15 and 5. A planetary A index of 30 indicates a geomagnetic

The next day on June 18 the forecast shifted to 25, 18 and 8, and on
June 19 it changed again to 25, 18 and 10. June 20 saw a slight
change to 25, 18 and 8 again, then June 21 it shifted to 15, 40 and
25.  An A index of 40 on the first day of Field Day sounds ominous.
Then June 22 it changed again to 30, 10 and 10, and now the June 23
prediction for June 24-26 shows a planetary A index of 30, 18 and

Basically we would love to see the A index as low as possible, five
or less would be wonderful.  The latest news is that the solar wind
from a Coronal Mass Ejection which occurred on the solstice is
moving slower than originally thought, which means a weaker effect
here on Earth.  A planetary K index of 5 is expected when the storm
arrives, now predicted at 0700z on June 24, which is 35 hours before
the start of Field Day, 1800z on June 25.

At 0640z on June 23, the Australian IPS Radio and Space Services
released a bulletin stating that increased geomagnetic activity is
expected on Jun4 23-24 due to the coronal mass ejection, but that
the effect on June 23 is expected to be mild, with a small chance of
isolated storm periods.

Geophysical Institute Prague predicts active conditions June 24,
unsettled to active on June 25, quiet to unsettled June 26-27, and
quiet on June 28-30.

The last forecast before Field Day should be on Friday, June 24,
released after 2100z. Check and also for the latest K
indices.  The similar shows you solar
flux, sunspot number, and other data such as sunspot area.

The most recent forecast from USAF and NOAA has solar flux at 95 on
June 24-25, 90 on June 26-30, 85 on July 1, and 95, 93 and 90 on
July 2-4  Predicted planetary A index for June 24-26 is 30, 18, and
12, 8 on June 27-28, and 5 on Jun 29 through July 1.

Ron Zond, K3MIY of Clarion, Pennsylvania found an interesting
article in an old QST from a half century ago.  John Chambers, W6NLZ
published "After Sunspots - What?" on pages 66-67 in the March 1960
QST.  I was about to dig out that old issue when I remembered that
ARRL members can access an archive of QST magazines running from
December 1915 to December 2007 at  I just
searched on Name: Chambers Call: W6NLZ Year: 1960 and went right to

This article was written just after the peak of Cycle 19 (which was
huge!) and in it the author speculates on what a future with little
or no sunspots might hold.

I thought W6NLZ seemed like a familiar call from my childhood, and
he was known back then for his VHF records establishing contact with
KH6UK.  Check out
for photos of both of them.

Thanks to Howard Lester, N7SO of Schuylerville, New York, K3CWF and
a number of others who sent in this article from Sky & Telescope
about disappearing sunspots:
Howard notes that there is no mention of the dissenting view.

Jeff Hartley, N8II of Shepherdstown, West Virginia sent in his
observations on recent conditions: "Conditions have seemed down from
2-3 weeks ago, but there has been a decent amount of sporadic-E as
we near the peak of the season which seems to me to be right around
July 1 on average. Late into the evening openings to EU on 15 meters
and higher have been much rarer, but there was some good propagation
reported in the All Asia CW contest by others.

"Around 0100Z Sunday on 15 phone, I worked Jim, E51JD in Rarotonga,
South Cook with a S9 signal. He was only running 100W to a small low

"Saturday June 18, I was active in the WV QSO party and the
sporadic-E continued to abound again this year as it did in 2010.
Not much was happening right at the 1600Z start, but by 1700Z skip
on 20 phone was short enough to work the other side of WV, southern
VA, and many in NC. I even worked a guy in Weaverville, NC in the
Smokies where I had stopped for breakfast a day ago - small world!
There were plenty of OH and KY stations for a while, then the band
opened to the northeast and even as close as DE about 140 miles from
here!  I managed to work all states except AK and VT (propagation
and QSO total to neighboring NH was good) in a few hours. 10M was
not quite good enough to spend much time there while I was able to
operate, but at 0100Z there was double hop Es to CA, NV, and AZ.

"On Friday June 17 around 2200Z, 6 meters was open to FM5AA, FM5AN,
V44KAI, and FG5FR.

"There were about the normal amount of Es on 6 meters during the
June VHF contest with C6, VP9, a few double hop stations in the
Rockies and lots of 4s, 5s and southern 0s logged."

Lawrence, GJ3RAX of the Isle of Jersey observes: "I have had some
comments from Nick VE3OWV. I have known him for a long time as we
were at university together in England in the early 60s. He has also
noticed that, although the sunspots have been increasing recently,
the propagation has not improved in the way it did at a similar
stage of previous cycles. We have not been able to get back to our
skeds on 17 that we used to keep so email has had to do instead. He
did say that he has been having QSOs to Europe on 17 at about 11 to
12 pm my time. Normally I only look on the bands during the
afternoons so I will start checking them again at that time. I used
to enjoy late night QSOs when I was younger but my stamina is now
rather less than it used to be!"

Check out K9LA, Carl Luetzelschwab's Propagation column on pages
16-19 in the July 2011 issue of Worldradio, which you can download
for free at He talks about signal
comparisons on the air in the 1980s, and how to use some new tools
such as internet connected remote receivers and a reverse beacon
network for similar comparisons today.

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 the
numbers used in this bulletin, see An archive of past
propagation bulletins is at Find more good
information and tutorials on propagation at

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

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bulletins are at

Sunspot numbers for June 16 through 22 were 62, 65, 67, 47, 43, 57,
and 44, with a mean of 55. 10.7 cm flux was 103.3, 104.3, 99.2,
99.1, 96.4, 95.1, and 92.9, with a mean of 98.6. Estimated planetary
A indices were 4, 11, 4, 4, 7, 10, and 12, with a mean of 7.4.
Estimated mid-latitude A indices were 3, 8, 4, 3, 7, 8, and 7, with
a mean of 5.7.