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ARRL Propagation Bulletin ARLP045 (2012)

ARLP045 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 45  ARLP045
From Tad Cook, K7RA
Seattle, WA  November 9, 2012
To all radio amateurs 

ARLP045 Propagation de K7RA

Again this week solar activity retreated.  Average daily sunspot
numbers declined 8.7 points to 49.7, and average daily solar flux
was down nearly 20 points to 97.2.

The latest forecast (from Thursday, November 8) shows solar flux at
105 and 110 on November 9-10, 115 on November 11-17, 110 on November
18-20, 105 and 100 on November 21-22, 105 on November 23-24, and 100
on November 25-26. Flux values then drop below 100 on November 27
through December 2.

The planetary A index forecast predicts an A index of 5 on November
9, 7 on November 10-12, 5 on November 13-18, 8 on November 19, 5 on
November 20 through December 4, and 10 on December 5-8.

Currently the Sun is peppered with a few weak spots, but there have
been 1-2 new sunspot groups every day starting on November 3.
November 3 had one new spot, November 4 had two, then two more on
November 5, one on November 6 and another on November 7, and two new
ones on November 8.

OK1HH has a new geomagnetic forecast from Prague, and he predicts
quiet to unsettled conditions November 9, active to disturbed
November 10, quiet to active November 11, quiet to unsettled
November 12, quiet November 13, mostly quiet November 14-15, quiet
again November 16-19, mostly quiet November 20, quiet November 21,
mostly quiet November 22-23, quiet November 24-26, quiet to active
November 27, active to disturbed November 28, quiet to unsettled
November 29, and quiet on December 1.

NASA tweaked their forecast for the smoothed sunspot number at the
peak of Cycle 24 next Fall. On October 2 they predicted a sunspot
number maximum of 75 in Fall 2013, and on November 2 they changed
that to 73.

Scott Wright, K0MD of Rochester, Minnesota shared some brief
observations on conditions during the CQ World Wide DX SSB Contest
(October 27-28, two weekends ago). He wrote, "I did not find the
band openings nearly as good this year as last year. Ten meters was
very good but not as good as 2011. Propagation was down on 40 meters
with lower country totals from the Midwest than I saw last year. 160
was not very good but no surprise there, given it is October."

Check out Scott's station at

The next CQ World Wide DX contest is the CW weekend, November 24-25.
See A week from now is the Phone weekend for
ARRL Sweepstakes, a domestic contest. See

Scott noted the better propagation during the same contest last
year.  This year, the average daily sunspot number for the ten day
period ending on Sunday, October 28, the last day of the contest,
was 79.8.  But for the same period last year, ending on Sunday,
October 30, 2011 the average daily sunspot number was 111.6, quite a
bit higher, by 40% in fact.

Max White, M0VNG of Worcester, UK sent this article about a coronal
hole and a disastrous solar wind back in January 1994:

We can check an archive of geomagnetic indices to get a sense of
what the effect on Earth was:

Note there are days in January of that year when readings from the
magnetometer near Fairbanks, Alaska (the College A index) that have
asterisks instead of numbers. This is what we see occasionally when
the magnetometer is completely overloaded with energy, and cannot
produce any sort of meaningful results.

We can see there was a lot of geomagnetic activity that year. I
would like to refer back to propagation forecast bulletins from
January 1994, but unfortunately the online archive at doesn't begin
until January 1995. If anyone has copies of the propagation bulletin
prior to 1995, please contact me.  Perhaps you have an old hard
drive from a personal computer used for packet radio twenty years

K9LA has some great propagation resources on his web site at He has download
links for free pdf copies of both NM7M propagation books, and a
slide presentation showing an update on Cycle 24 that he presented
in July. If you don't have Microsoft PowerPoint to watch the slides,
you can download a free reader at

From two years ago, G0KYA has a downloadable pdf eBook titled
"Understanding LF and HF Propagation" at

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

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for November 1 through 7 were 48, 34, 35, 46, 47,
61, and 77, with a mean of 49.7. 10.7 cm flux was 98.4, 96.5, 93.3,
95, 96.6, 98.7, and 101.7, with a mean of 97.2. Estimated planetary
A indices were 17, 5, 3, 2, 2, 4, and 10, with a mean of 6.1.
Estimated mid-latitude A indices were 17, 5, 2, 1, 2, 4, and 10,
with a mean of 5.9.


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