SB PROP @ ARL $ARLP019
ARLP019 Propagation de K7RA

ZCZC AP19
QST de W1AW
Propagation Forecast Bulletin 19  ARLP019
> From Tad Cook, K7RA
Seattle, WA  May 12, 2017
To all radio amateurs

SB PROP ARL ARLP019
ARLP019 Propagation de K7RA

Average daily sunspot numbers this week (May 4-10) were 17.1, down from 25.1
last week. Average daily solar flux declined from 76.9 to 71.5.

There were three consecutive days with 0 sunspots this week, May 9-11.
Spaceweather.com noted that Thursday was the thirty-third day with 0 sunspots
in 2017, and through all of 2016 there were 32 days with no sunspots. Being
early May, this indicates an acceleration of the decline of the current solar
cycle.

Predicted solar flux is 71 on May 12-13, 70 on May 14-17, 80 on May 18-23, 77
on May 24-27, 75 on May 28 through June 1, 73 on June 2, 72 on June 3-4, 70 on
June 5-8, 72 on June 9-10, 75 on June 11, and 80 on June 12-19.

Predicted planetary A index is 6 on May 12, 5 on May 13-16, 15 on May 17-18,
then 8, 15, 30, 20, 10 and 8 on May 19-24, 5 on May 25 through June 3, 8 on
June 4, 5 on June 5-7, then 8, 5, 5 and 8 on June 8-11, then 15, 30, 15 and 8
on June 12-15.

Both above Ap and 10.7 cm SF forecasts are from Wednesday May 10. As of 1430
UTC Friday the Thursday May 11 forecast (normally out after 2100 UTC daily) was
 still unavailable.

You can check ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ for daily updates of
predicted Ap (planetary A index) and solar flux predictions.


OK1HH gives us his geomagnetic activity forecast for May 12-June 7, 2017.

"Geomagnetic field will be:
Quiet on May 14-15, June 1,
Mostly quiet on May 13, June 4
Quiet to unsettled May 12, 23-30, June 3, 5-7
Quiet to active on May 16, 20, 21-22, June 2
Active to disturbed on May (17-19, 31)

"Amplifications of the solar wind from coronal holes are expected May 16-19
(and maybe about May 29-30 and June 3, 6, 7-8)

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

"F.K. Janda, OK1HH Czech Propagation Interested Group OK1HH compiling weekly
forecasts since 1978."


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-ionosph...

An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propag... 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 May 4 through May 10, 2017 were 29, 31, 26, 23, 11, 0, and
0, with a mean of 17.1. 10.7 cm flux was 74.2, 73.5, 72.8, 71.7, 70.5, 68.9,
and 68.6, with a mean of 71.5. Estimated
planetary A indices were 7, 6, 5, 8, 6, 6, and 6, with a mean of 6.3. Estimated
 mid-latitude A indices were 6, 5, 5, 7, 7, 5, and 6, with a mean of 5.9.

NNNN
/EX

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