Register Account

Login Help

ARRL Propagation Bulletin ARLP045 (2015)

ARLP045 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 45  ARLP045
From Tad Cook, K7RA
Seattle, WA  November 6, 2015
To all radio amateurs 

ARLP045 Propagation de K7RA

Solar activity increased over last week, with the average daily
sunspot number rising from 77.6 to 90.3, and average daily solar
flux from 110.9 to 118.3. These comparisons contrast October 29
through November 4 with the previous seven days.

A high speed solar wind caused aurora on November 3-4 and the high
planetary A index of 32 and 33 on those days.

Predicted planetary A index is 8 on November 6, 25 on November 7-8,
then 15 and 12 on November 9-10, 8 on November 11-12, then 12, 20,
5, 8 and 12 on November 13-17, 5 on November 18-21, then 10, 5, 8
and 12 on November 22-25, and 10 on November 26-27. Planetary A
index then jumps to 50 and 40 on November 30 and December 1, when
the same region causing aurora the past few days rotates back into

Predicted solar flux is 110 on November 6, 115 on November 7-8, 120
on November 9-12, 105 and 110 on November 13-14, 115 on November
15-16, then 120, 115 and 110 on November 17-19, and 105 on November
20-24. Flux values dip below 100 on November 27 through December 8,
reaching a low of 85 on November 30 through December 5.

F.K. Janda, OK1HH of the Czech Propagation Interest Group sent his
geomagnetic forecast, and he expects the geomagnetic field to be
quiet to unsettled on November 6, active to disturbed November 7-8,
quiet to active November 9, quiet to unsettled November 10, quiet to
active November 11, quiet on November 12, quiet to unsettled
November 13, quiet to active November 14, quiet on November 15,
quiet to active November 16, quiet to unsettled November 17, mostly
quiet November 18-19, quiet to unsettled November 20, mostly quiet
November 21, quiet on November 22, quiet to unsettled November 23,
mostly quiet November 24, quiet on November 25, quiet to active
November 26, quiet to unsettled November 27, mostly quiet November
28-29, active to disturbed November 30, and quiet to active December

OK1HH expects increases in solar wind on November 7-8, 10-11, 15,
18, and 29. There us a chance of increased solar wind, although less
likely, on November 19-21 and 30.

The average daily sunspot number for October 2015 was 59.6, the
lowest since September 2013, when it was 55. February 2012 was even
lower, at 50.1.

For our 3-month moving average of daily sunspot numbers, the highest
average for the current solar cycle was centered on February and
March 2014, when it was 146.4 and 148.2. The 3-month averages
centered on December 2014 through September 2015 were 107.8, 98.2,
78.1, 68.2, 72.4, 77.7, 76.3, 69.1, 67.5 and 64.5. The September
number is the average of all daily sunspot numbers from August 1
through October 31.

This weekend is ARRL CW Sweepstakes and the high geomagnetic
activity expected for Saturday and Sunday could be a problem.
Predicted planetary A index for November 7-8 is 25 on both days.

At 2320 UTC on November 5, the Australian Space Forecast Centre
issued a geomagnetic disturbance warning: "The partial halo coronal
mass ejection associated with the 4 November M3.7 flare has an
Earth-directed component. It is likely to impact Earth late on UT
day Nov 06/2200 or thereabout. As a result, minor to major
geomagnetic storms could occur on UT day 07 Nov depending on IMF Bz

Here is info on the Interplanetary Magnetic Field Bz:

David Moore sent this article about the U.S. government plans for
dealing with problematic space weather:

David also sent this link to a high definition video of the Sun:

Robert Wood, W5AJ of Midland, Texas noted that sunspot 2443 is close
to the Sun's equator, and we both got to wondering what this means
regarding the current sunspot cycle projection. I couldn't remember.

A check of butterfly diagrams shows us that early in a solar cycle,
sunspots appear further north or south of the solar equator, and
gradually appear close to the equator as the cycle progresses:

So this sunspot is probably typical of spots appearing after the
peak of the solar cycle.

A sign that the solar cycle is transitioning to the next cycle is
when the magnetic signature of sunspots begins to change. In the
most recent magnetogram, we can see the north magnetic polarization
as the white splotches, and south as black:

You can click that image to see it with higher resolution.

This image is in real time, so by the time you see it in the future,
the image may have changed significantly.

Here is an article from nine years ago about sunspot polarization.

As the solar cycle transitions from one to the next, that
polarization will change, with an increasing number of new cycle
spots gradually replacing the old. But don't expect this until five
years from now.

Mike Treister, W9NY who operates from Chicago, Illinois and another
station on a sand dune in Dune Acres, Indiana at the southern tip of
Lake Michigan filed this report:

"I was very surprised at the excellent conditions on 10 and 15
meters during the CQ WW SSB contest. From my QTH in Dune Acres,
Indiana, 10 meters was chock full of activity most of the morning
with many European stations well over S9 all the way from 28.3 up to
29 MHz. I stayed near the top and had no problem running stations.
The band was really packed, just like the good ole days.

"But the real surprise was 15 meters which remained open for nearly
the entire day. While I had my TH7 pointed at Europe I was getting
calls from Hawaii, Alaska, the Middle East, South America, etc. Late
in the afternoon, with my beam pointed toward Asia, I was running
lots of strong Japanese stations, and also got calls from China,
India, Indonesia, Siberia, the Philippines etc. etc. And while doing
this I was still getting calls from basically all over the world off
the sides and back of my beam. Heard some flutter echo suggesting
long path propagation at times.

"Also, in the early morning hours, 40 meters was terrific.

"What an unexpected fun weekend!

"Perhaps conditions are frequently good, like this, and there is
just very little activity!"

Yes, I agree.  And a big HF contest brings out the activity to
reveal propagation paths otherwise unheard.

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

My own archives of the NOAA/USAF daily 45 day forecast for solar
flux and planetary A index are in downloadable spreadsheet format at and .

Click on "Download this file" to download the archive, and ignore
the security warning about file format. Pop-up blockers may suppress
the download.

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 October 29 through November 4 were 101, 88, 73,
88, 94, 95, and 93, with a mean of 90.3. 10.7 cm flux was 112.9,
112.1, 118.5, 124.3, 122, 124.2, and 113.8, with a mean of 118.3.
Estimated planetary A indices were 5, 9, 6, 11, 7, 32, and 33, with
a mean of 14.7. Estimated mid-latitude A indices were 4, 6, 6, 9, 5,
23, and 31, with a mean of 12.


Instragram     Facebook     Twitter     YouTube     LinkedIn