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ARRL Propagation Bulletin ARLP006 (2016)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 5, 2016
To all radio amateurs 

ARLP006 Propagation de K7RA

Over the recent reporting week (January 28 through February 3) both
sunspot and solar flux averages were down a negligible amount, and
geomagnetic numbers were down substantially, compared to the
previous seven days.

Average daily sunspot numbers declined from 57.3 to 50.6, while
average daily solar flux values went from 106 to 105.4. Average
daily planetary A index softened from 11.6 to 7.3, while the
mid-latitude A index (measured in Fredericksburg, Virginia) went
from 7.6 to 5.6.

The latest predicted solar flux is 125 on February 5-6, 120 on
February 7, 115 on February 8, 110 on February 9-11, 105 on February
12-20, 100 on February 21 through March 2, 95 on March 3, 90 on
March 4-5, 95 on March 6-8 and 105 on March 9-18.

Predicted mid-latitude A index is 6 on February 5, 5 on February 6,
then 8, 18, and 12 on February 7-9, 6 on February 10-11, 5 on
February 12-16, then 10, 15, 12 and 10 on February 17-20, 5 on
February 21-27, then 8 on February 28-29, 15 and 8 on March 1-2, 5
on March 3-5, then 12, 10 and 8 on March 6-8 and 5 on March 9-15.

OK1MGW predicts geomagnetic activity will be mostly quiet February
5-6, quiet to active February 7-8, quiet to unsettled February 9-10,
mostly quiet February 11, quiet February 12-14, quiet to unsettled
February 15, quiet to active February 16-18, quiet to unsettled
February 19-20, mostly quiet February 21, quiet February 22-25,
mostly quiet February 26-28, quiet to active February 29 through
March 1, and quiet to unsettled March 2.

During the March 16-18 period when he predicts quiet to active
conditions, we may see active to disturbed conditions March 16-17,
although he is uncertain about this.

He says we may see increased solar wind on February 7-8, 16-18 and
February 29 through March 1.

Skip Burroughs, KS5KIP of Capitan, New Mexico sent a query about how
to apply some of the data from this bulletin to get a feel for what
propagation will be like.

One way to do this is to use a propagation prediction program and do
predictions based on your location for various locations and
frequencies of interest.

One free program for doing this is W6ELprop, which you can download
from .  K9LA has some
more info on running the program here: and here:

Basically what we want to see in the weekly numbers are rising solar
flux and sunspot numbers and lower A index, at least ideally.

You could take the average daily sunspot number from the bottom of
this bulletin (50.6 in this bulletin) and use that in the program.
If we run that for Capitan, New Mexico for this Sunday toward Japan,
we see that 40 meters should be good 0600-1500 UTC, with best
signals around 0900-1400 UTC. 30 meters seems good 0700-1430 UTC, 20
meters looks rather weak, but possibilities include 2100-0300 UTC
and another possible opening at 1500-1600 UTC. 17 meters looks much
stronger 2130-0200 UTC, and 15 meters 2200-0030 UTC. 12 meters looks
promising 2230-2330 UTC.

From Capitan to Chicago, 15 meters looks possible 1730-2000 UTC, 17
meters looks better 1630-2200 UTC, 20 meters 1500-0000 UTC and 30
meters 1330-0130 UTC. 40 meters looks excellent any time of the day
or night, with best signals 0100-1300 UTC and open, but about 13 db
lower signals but still open 1730-1930 UTC. 75 meters looks best
0130-1230 UTC.

Vary the date using the same numbers, and you will see seasonal
effects on propagation. For instance, the path to Japan on March 22
opens on 17 meters an hour earlier and closes over 2 hours later.

Next week I should have an evaluation copy of ACE-HF, another
propagation tool and I hope to review it.

Now that January is over, we can look at our 3-month moving averages
of sunspot numbers t check the progression of this solar cycle. This
gives us the latest number, centered on December 2015.

We saw the peak centered on February and March 2014, when the three
month moving averages were 146.4 and 148.2. The highest single
monthly average at the peak of the solar cycle was February 2014, at

The latest 3-month average was 55.4 centered on December 2015, which
included all of the daily sunspot numbers from November 1, 2015
through January 31 2016.

The 3-month moving averages of sunspot numbers centered on January
through December 2015 were 98.2, 78.1, 68.2, 72.4, 77.7, 76.3, 69.1,
67.5, 64.5, 64.6, 58.5 and 55.4. With this moving average you can
see a smooth, steady decline in cycle 24.

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 site 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 January 28 through February 3 were 64, 49, 30,
39, 42, 52, and 78, with a mean of 50.6. 10.7 cm flux was 109.9,
106.9, 105.1, 101.2, 100.2, 102.1, and 112.1, with a mean of 105.4.
Estimated planetary A indices were 6, 3, 3, 10, 9, 6, and 14, with a
mean of 7.3. Estimated mid-latitude A indices were 5, 3, 3, 8, 6, 4,
and 10, with a mean of 5.6.


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