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ARRL Propagation Bulletin ARLP004 (2016)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 22, 2016
To all radio amateurs 

ARLP004 Propagation de K7RA

Over the past week we saw solar activity decline somewhat. Average
daily sunspot number declined from 55.7 (during the January 7-13
period) to 46 during the recent period, January 14-20.

Over the same periods average daily solar flux declined from 106.5
to 100.7. Average daily planetary A index went from 11.1 to 9, and
average daily mid-latitude A index declined from 8.4 to 5.6.

Predicted solar flux is 105 on January 22-23, 110 on January 24-28,
then 105, 100 and 105 on January 29-31, 110 on February 1-4, 105 on
February 5-11, 100 on February 12-14, 95 on February 15-19, and 105
on February 20-25.

Predicted planetary A index is 12 on January 22, 8 on January 23-24,
10 on January 25-26, then 9, 5, 12 and 8 on January 27-30, 5 on
January 31 through February 1, then 15, 12 and 8 on February 2-4, 5
on February 5-6, 12 on February 7-8, 10 and 8 on February 9-10, 5 on
February 11-17, then 8, 12 and 8 on February 18-20 and 5 on February

We saw one new sunspot on January 14, another on January 17, and two
more on January 19 and 20. At 0530 UTC on Friday, January 22 I can
see four numbered sunspot regions on the Sun.

A forecast from OK1MGW predicts quiet to unsettled conditions on
January 22, mostly quiet January 23-25, quiet to unsettled January
26, quiet to active January 27, active to disturbed January 28,
quiet to unsettled January 29-30, mostly quiet January 31, quiet to
unsettled February 1, quiet to active February 2-3, mostly quiet
February 4-6, quiet to active February 7-8, quiet to unsettled
February 9-10, mostly quiet February 11, quiet February 12-14 and
mostly quiet February 15-17.

He expects increases in solar wind on January 27-28, February 1-3
and 7-8.

David Moore sent a link to an article and video titled "Solar
Filament Collapses In Stunning New NASA Sun Video." See it at .

Solar activity has been weak, and this chart of solar activity over
the past year bears this out:

But we should see some seasonal improvements in HF propagation over
the next few months the days become longer and we move toward the
Spring Equinox in the Northern Hemisphere.

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 14 through 20 were 36, 38, 38, 48, 48,
55, and 59, with a mean of 46. 10.7 cm flux was 103.2, 103.5, 99.9,
100.6, 99.9, 97.5, and 100.4, with a mean of 100.7. Estimated
planetary A indices were 8, 6, 4, 4, 5, 11, and 25, with a mean of
9. Estimated mid-latitude A indices were 6, 4, 3, 3, 4, 7, and 12,
with a mean of 5.6.


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