SB PROP @ ARL $ARLP014
ARLP014 Propagation de K7RA

ZCZC AP14
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 http://bit.ly/2o5Ts6g shows a nice image from a few days back of
sunspot AR2644 and 2645. Also check http://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:

http://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 k7ra@arrl.net.

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

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

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

Instructions for starting or ending email distribution of ARRL bulletins are at
http://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.

NNNN
/EX

)\/(ark

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