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ARRL Propagation Bulletin ARLP023 (2013)

ARLP023 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7RA
Seattle, WA  June 7, 2013
To all radio amateurs 

ARLP023 Propagation de K7RA

Solar activity seems to dip back into the doldrums again, with the
average sunspot number for the past week (72) lower than any
reporting week since Propagation Forecast Bulletin ARLP013, which
was for the week of March 21-27. You can go through the recent
bulletins at
and note that two weeks ago we had twice that number, when the
average daily sunspot number was 144. From last week, the average
dropped more than 12 points from 94.3. Average daily solar flux was
down more than 10 points to 107.6.

But tracking the 3-month moving average of daily sunspot numbers,
(which is based on calendar months) the three months ending May 31
had a much higher average than the 3 months ending April 30, and in
fact more than any trailing three month average since the one ending
on January 2012.

At the end of 2011 we saw a rally in solar activity, and with the
weak activity in all of 2012 some are suggesting another
double-peaked solar cycle. The three month periods centered on July
through December 2011 had average sunspot numbers of 63, 79.6, 98.6,
118.8, 118.6 and 110. The first few months of 2012 were weaker, with
the 3-month averages centered on January through March at 83.3, 73.7
and 71.2. But now the numbers are trending up. The 3-month averages
centered on January through April 2013 were 73.6, 80.7, 85.2 and

If you are unfamiliar with moving averages, using our method for the
3-month period centered on March, 2013, we added up all the daily
sunspot numbers from February 1 through April 30. The sum was 7,581.
We divided by the 89 days in those three months, and got
approximately 85.2. For the period centered on April, we added all
sunspot numbers from March 1 through May 31, and the sum was 9,792.
As there were 92 days in this period, the average rounds off to

On June 3 NASA updated their forecast for the peak of the current
solar cycle, available at This differs from a
month earlier, when on May 1 they predicted a cycle maximum in Fall
2013 with a smoothed international sunspot number of 66. Now they
predict a peak at 67 in Summer 2013. Summer officially begins at the
Solstice, two weeks from today, on June 21 at 0504 UTC, which by the
way is the Friday before Field Day weekend.

The active geomagnetic days over the past week were June 1-2, when
the planetary A index was 49 and 19, the mid-latitude index was 41
and 16, and the high latitude college A index (measured near
Fairbanks, Alaska) was 58 and 44. These numbers reflect the
concentration of geomagnetic activity toward the poles. The source
was an interplanetary shock wave of uncertain origin.

Again as this bulletin is written early Friday morning on the West
Coast, we are in a geomagnetic storm, the result of the Earth
passing through south-pointing magnetism in the solar wind. There is
a possibility on June 8 of getting buffeted again, this time the
result of a CME, and possibly two.

The planetary A index was 17 on June 6, with increasing K-index
values from 2 to 3 to 4. Now early on June 7 we see planetary
K-index of 5 and 6, which is the equivalent to an A index reading of
64. Now after 1200 UTC it dropped to 56.

The Australian Space Forecast center issued a geomagnetic
disturbance warning at 0217 UTC on June 7. It reads, "A CME from a
disappearing solar filament has arrived earlier than anticipated and
is accompanied by a strongly southward pointing magnetic field. This
is producing Minor Storm levels of activity in polar regions and may
produce Active conditions at mid latitudes over the next 1-2 days."
They predict a minor geomagnetic storm today, June 7, and unsettled
to active conditions through the weekend, June 8-9.

The latest prediction from USAF/NOAA is for solar flux at 110 on
June 7, 105 on June 8-9, 100 on June 10, 95 on June 11-12, 100 and
105 on June 13-14, 120 on June 15-16, 125 on June 17-19, then with
flux values bottoming out at 105 on June 24-28, and rising to 125 on
July 2 and again on July 14-16.

Predicted planetary A index is 18 on June 7-8, then 10 and 8 on June
9-10, 5 on June 11-20, then 25, 18, 10 and 8 on June 21-24, 5 on
June 25-27, then 30, 20, 12, 8, 5, 8, 12, 10 and 5 on June 28
through July 6.

Petr Kolman, OK1MGW predicted a quiet geomagnetic field for June 7
(the prediction was sent around 1900 UTC on June 6), mostly quiet
June 8-9, quiet June 10, quiet to unsettled June 11, quiet to active
June 12-14, mostly quiet June 15-17, quiet June 18, quiet to
unsettled June 19-20, active to disturbed June 21, quiet to active
June 22-23, quiet to unsettled June 24, mostly quiet June 25-26,
quiet to active June 27, and active to disturbed June 28-29. You can
see quite a difference from the NOAA/USAF prediction in the previous
paragraph, but the NOAA forecasters have the advantage of revising
their forecast every 24 hours, while OK1HH and OK1MGW only do it
once per week.

Bert Cook, K6CSL of Riverbank, California, which is northeast of
Modesto in the San Joaquin Valley, wrote to comment about the ARRL
Propagation Charts. He finds them useful, but said the monthly
charts are never available until well into the new month. I checked
and learned these are prepared by the lab at ARRL headquarters, but
the delay is due to some technical issues that may not be resolved
right away.

As these are prepared using the VOACAP prediction engine, I
suggested an alternative that should suit his needs if he would
rather not set up the VOACAP program himself. Several months back we
mentioned the subscription service at There is
a free 30-day trial, and if you should choose to continue, the
subscription cost is reasonable. This has the advantage of
customization for the user's exact location, plus you can make
predictions for future months as well.

You can also customize your account for antennas and power levels,
and when you run the program it emails you a set of URLs for the
bands you have chosen as well as the region, either North America or
world wide. Rather than look at these online, I found it much better
to download the PDF files, then page through the 24 hourly pages for
each band. You get a set of beautifully rendered maps with colors
corresponding to coverage areas and signal levels. When you can
quickly flip through these after downloading, you watch the
projection of the signal levels for different areas progress across
the map, hour-by-hour.

Another alternative is to use the free W6ELprop software for Windows
computers. Check the K9LA tutorial at,
and you can download the software at
W6ELprop is free, but K6TU tells me he is about to add some great
new features to his service.

Larry Nelson, K5IJB of El Paso, Texas reports: "Several 6-meter CW
beacon stations were very helpful last Sunday (June 2) when
listening for band openings. From about mid-morning up to noon,
these beacons were S9 as the band opened to the West and mid-West
from El Paso: N0LL/B, N7DGI/B, WB0RMO/B, W5GPM/B and N0SAP/B. I made
several CW and SSB contacts using the Icom 703 (10 watts) to a
homebrew vertical dipole at 25 feet."

Lou DiChiaro, WB2IJT reported, "As a Navy civilian physicist, I
don't get to spend much time on the air during the work week.
However, I do occasionally get on the air over the weekends. This
past Saturday (June 1) was an extraordinary day for Es on 6 meters.
I'm running 100 watts out from an IC-7000 to a large loop antenna
running around the inside perimeter of my attic (to avoid the wrath
of the subdivision esthetics enforcers). From Grid Square FM29
(Delaware) I worked in quick succession a number of Florida
stations, some in Georgia, Arkansas, and Missouri. One of the
Georgia stations measured S9+20 dB on the S meter (he was running a
KW into a 5 element Yagi - it helps!).

"It was a band opening to remember. And I'll bet you're getting lots
of reports like mine. Hopefully, we'll get lots more openings like
this from Old Sol before he runs out of hydrogen and starts burning
helium in his core."

And finally, Jeff Hartley, N8II reports from West Virginia: "From
0245-0400Z Friday May 31 I caught the best conditions towards EU on
15M I can ever remember so late in the evening, in 42 years on the
air.  Since the solar flux was around 120, my guess would be there
was a sporadic-E link to the opening on the North American end, but
the stations worked were in daylight ranging from around sunrise to
mid morning. Prefixes worked in order from 0242-0306Z on 15 CW were
DJ2, UT7, UA3, UT9, RA1, RA4LW (S9+5dB, then +20 dB at 0330Z!),
UK8OWW, SP7.  Then, I tried some CQs on 12M with no answer and
scanned 10M towards EU where there were no signals to the NE
including beacons, but several W6 beacons were loud via double hop
Es. I went back to 15 CW at 0328Z and worked RU4, YO4, LA6, RZ6,
UB6, UR4, UX7, RD3, UA6, and LZ2 thru 0352Z.

"I made a quick check of 15 SSB and found Ed, 4Z4UR who was S9. He
mentioned he uses WWV near Fort Collins on 20 MHz often as a
propagation indicator for NA, a smart idea. He says he can
frequently hear WWV around 0300-0400Z at this time of year
indicating a band opening which I would guess rarely extends as far
east as my QTH in FM19cj. I checked 15 the next night around the
same time and there was no opening to anywhere.

"On June 1 from 0125-0149Z, I did catch UN5C and UN5J with good
signals on 17M CW as well as FO8WBB, ZL1BD, and a VP2V on 12M. 10M
was dead including beacons. During the day I worked the Alabama QSO
party in which even 10M was open to Alabama on Es from 19Z thru
about 0020Z, though it was not utilized by most Alabama stations.
All of the stations I asked to QSY to 10M up from 15 or 20M were
successfully logged mostly with very strong signals. 15 was fairly
active on CW and 20 was in great shape with strong signals all day
until about 0120Z.  40M was barely usable at first, but was open
from here pretty well from 2045Z onward. The high bands were the
best ever to Alabama in the ALQP from here. In the late afternoon, I
also worked AF3X/M on 20 roaming around the NYC boroughs with S9
signals only about 250 miles away.

"I operated part time in the WPX CW contest May 25-26 on 20M.
Conditions were disturbed at the beginning, then quite so Saturday
1200Z thru at least 0300Z Sunday. There were some very loud southern
and central EU at the start thru around 0115Z when the band
gradually closed. A few Russians and Asians were found, but were
almost gone by 0215Z whereas normally I have run pile ups from
western Asiatic and European Russians from 0200-0400Z on 20 CW.
Sunday 0100-0200Z was pretty much rock bottom, but I managed somehow
to work all continents except EU during that time. RC9O who would
normally peak around 20 degrees peaked around 310 degrees on a very
skewed path and was only about S4. SA was loud and I worked KH7 and
ZL3. Sunday at 1400Z, 20 seemed back to near normal as it did at
2345Z, but I only had time to operate mainly in the 14Z hour when
many northern EU stations not possible to work before due to
conditions were logged."

Thanks, Jeff!

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 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 May 30 through June 5 were 71, 58, 60, 76, 99,
59, and 81, with a mean of 72. 10.7 cm flux was 104.1, 101.8, 105.8,
110.9, 111.8, 109.9, and 108.8, with a mean of 107.6. Estimated
planetary A indices were 3, 9, 49, 19, 10, 10, and 6, with a mean of
15.1. Estimated mid-latitude A indices were 2, 7, 41, 16, 9, 10, and
9, with a mean of 13.4.


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