QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
>From Tad Cook, K7RA
Seattle, WA  April 7, 2017
To all radio amateurs 

SB PROP ARL ARLP014
ARLP014 Propagation de K7RA

Sunspot numbers and solar flux made a strong comeback over the past
week, March 30 to April 5.

Average daily solar flux was 96.5 (compared to 77.9 the previous
seven days, and 71.2 over the week before that, March 16-22).

Average daily sunspot number progressed from 3.4 to 29.7 to 65.9
over the same three weeks.

The latest daily forecast for Planetary A index and solar flux from
NOAA and USAF (updated daily at
ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ ) shows solar flux at 76
on April 7, 70 April 8-13, 75 on April 14, 78 on April 15-16, 85 on
April 17-19, 72 on April 20-23, 88 on April 24-27, 85 on April
28-29, 105 on April 30, then 100, 97, 92, 85, and 80 on May 1-5, 75
on May 6-7, 78 on May 8-9, 75 on May 10-11, 78 on May 12-13, 85 on
May 14-16, and 92 on May 17-20.

The same forecast, but for planetary A index, shows 8 on April 7-8,
then 5, 8, and 10 April 9-11, 8 on April 12-13, 5 on April 14-16,
then 20, 18 and 10 on April 17-19, 5 on April 20-22, then 55, 28,
20, 22, and 28 on April 23-27, then 15, 10, 8, 7 and 6 on April 28
through May 2, 5 on May 3-13, 20, 18, and 10 on May 14-16, 5 from
May 17-19, then 55 and 28 on May 20-21.

The site bit.ly/2o5Ts6g shows a nice image from a few days
back of sunspot AR2644 and 2645. Also check bit.ly/2nNpeCC .

F.K. Janda, OK1HH sent us this geomagnetic activity forecast for the
period April 7-May 2, 2017.

'Geomagnetic field will be:
Quiet on April 9-10, 14-16, 20, 30
Mostly quiet on April 8, 11, 19, 21, 29, May 2
Quiet to unsettled April 12-13, May 1
Quiet to active on April 7, 22, 24-28
Active to disturbed on April 17-18, 23

'Amplifications of the solar wind from coronal holes are expected on
April (7-8,) 11-13. (15,) 16-19, 24-27

'Remark: - Parenthesis means lower probability of activity
enhancement and/or lower reliability of prediction.'

Thanks to David Moore (long time contributor to this bulletin) for
this, on fast magnetic reconnection:

bit.ly/2nkGwe8

Max White, a British ham, sent this:

https://go.nasa.gov/2nqXBiy

If you would like to make a comment or have a tip for our readers,
email the author at [email protected].

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
arrl.org/propagation-of-rf-signals. For an explanation of
numbers used in this bulletin, see
arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at k9la.us/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at arrl.org/bulletins.

Sunspot numbers for March 30 through April 5, 2017 were 33, 65, 79,
75, 97, 75, and 37, with a mean of 65.9. 10.7 cm flux was 85.9,
90.6, 101, 112, 107.9, 93.8, and 84.6, with a mean of 96.5.
Estimated planetary A indices were 23, 28, 16, 8, 4, 20, and 10,
with a mean of 15.6. Estimated mid-latitude A indices were 18, 21,
15, 6, 4, 17, and 10, with a mean of 13.