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ARRL Propagation Bulletin ARLP003 (2016)

ARLP003 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 3  ARLP003
From Tad Cook, K7RA
Seattle, WA  January 15, 2016
To all radio amateurs 

ARLP003 Propagation de K7RA

Trends over the past week were just the way we like them, with
average daily sunspot numbers and solar flux increasing, and
geomagnetic indices lower, compared to the previous seven days.

Why do we like these numbers? When solar flux and sunspot numbers
are higher, this increases the likelihood that there will be
openings on HF. Lower geomagnetic indices suggest lower absorption.

Average daily sunspot numbers rose from 41 to 55.7, and average
daily solar flux increased from 98.2 to 106.5. Average daily
planetary A index declined from 16.6 to 11.1, while average daily
mid-latitude A index went from 10.6 to 8.4.

These comparisons are for the January 7-13 period against the
previous seven days.

Predicted solar flux is 105 on January 15, 110 on January 16-18, 105
on January 19-21, 100 on January 22, 105 on January 23-26, 110 on
January 27-28, 105 on January 29-31, 110 on February 1-7, then 108,
105 and 100 on February 8-10, 105 on February 11-14, 100 on February
15-18 and 105 on February 19-22.

Predicted planetary A index is 5 on January 15-21, 15 on January 22,
10 on January 23, 5 on January 24-27, then 18, 12 and 8 on January
28-30, 5 on January 31 through February 1, then 15, 12 and 8 on
February 2-4, 5 on February 5-6, then 6, 15, 12 and 8 on February
7-10, 6 on February 11-13, 5 on February 14-16, 8 on February 17 and
15 on February 18.

F.K. Janda, OK1HH of the Czech Propagation Interest Group predicts
quiet to unsettled geomagnetic conditions on January 15, quiet to
active January 16, quiet to unsettled January 17, mostly quiet
January 18, quiet to active January 19-20, mostly quiet January 21,
quiet to active January 22, mostly quiet January 23-24, quiet on
January 25, quiet to unsettled January 26, active to disturbed
January 27, quiet to active January 28, quiet on January 29-31,
quiet to active on February 1-2, quiet to unsettled February 3,
quiet on February 4-5, mostly quiet February 6-7, active to
disturbed February 8 and quiet to active February 9.

There are a couple of articles about propagation in the February
2016 issue of QST. Check out "Radio Wave Propagation: How Waves
Attenuate With Distance" by Kai Siwiak, KE4PT on page 37, and "Make
the Most of Ten Meters" by Steve Ford, WB8IMY on page 83.

Sorry, no reader reports this week.

Have you tried the online version of the VOACAP propagation
prediction program? It's easy to use, and quite versatile. You can
drag the endpoints of any path around the map, and the polar display
to the right of the map gives you the hour-by-hour outlook for each
band. VOACAP uses the predicted smoothed sunspot number for the
month to make the predictions, and that number is already
incorporated in the predictions here.

Check it out 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 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 7 through 13 were 57, 80, 84, 73, 41,
29, and 26, with a mean of 55.7. 10.7 cm flux was 103.4, 108.5, 107,
108.9, 108, 105.5, and 104.1, with a mean of 106.5. Estimated
planetary A indices were 14, 8, 6, 7, 14, 15, and 14, with a mean of
11.1. Estimated mid-latitude A indices were 11, 6, 5, 7, 9, 10, and
11, with a mean of 8.4.


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