QST de W1AW  
Propagation Forecast Bulletin 35  ARLP035
>From Tad Cook, K7RA
Seattle, WA  September 1, 2017
To all radio amateurs 

SB PROP ARL ARLP035
ARLP035 Propagation de K7RA

A new video from Dr. Skov:
 
https://youtu.be/qvjfFpRMQpY
 
Average daily sunspot numbers and solar flux declined this week
(August 24 to 30).  Average daily sunspot number went from 39.9 to
33.3, while average daily solar flux declined to 81.2 from 84.6.
 
Average planetary A index declined from 23.1 to 7.1, and average
mid-latitude A index went from 18.6 to 7.4.
 
The latest forecast shows planetary A index at 24, 16, 12 and 8 on
September 1 to 4, 5 on September 5 and 6 then 8, 10 and 8 on
September 7 to 9, 5 on September 10 to 12, 25 on September 13, 30 on
September 14 and 15, then 25 and 12 on September 16 and 17, 8 on
September 18 and 19, 5 on September 20 to 22, 10 on September 23 and
24, then 8, 15, 25, 18, 15 and 8 on September 25 to 30, then 5 on
October 1 to 4, 10 and 8 on October 5 and 6, 5 on October 7 to 9, 25
on October 10, 30 on October 11 and 12, then 25, 12 and 8 on October
13 to 15.
 
Predicted solar flux is 92 on September 1 and 2, 91 on September 3,
90 on September 4 to 7, 80 on September 8, 85 on September 9 to 14,
88 on September 15 to 18, 85 on September 19 and 20, then 82 and 80
on September 21 and 22, and 78 on September 23 to 25, 77 and 75 on
September 26 and 27, 74 on September 28 and 29, 72 on September 30
through October 3, 75 and 80 on October 4 and 5, 85 on October 6 to
11 and 88 on October 12 and 15.
 
Geomagnetic activity forecast for the period September 1 to 27, 2017
from OK1HH.
 
'Geomagnetic field will be: 
Quiet on September 10 and 11, 20 and 21
Mostly quiet on September 4 to 6, 23, 26 
Quiet to unsettled September 3, 8 and 9, 19, 22, 27 
Quiet to active on September 2, 7, 12, 16 and 17, 24 
Active to disturbed on September 1, 13 to 15, 18, 25
 
Remark: Parenthesis means lower probability of activity enhancement
and/or lower reliability of prediction.'
 
For more information concerning radio propagation, see the ARRL
Technical Information Service 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 August 24 to 30, 2017 were 43, 39, 35, 22, 17,
35, and 42, with a mean of 33.3. 10.7 cm flux was 78.8, 80.8, 77.5,
78.2, 81.6, 84.3, and 86.9, with a mean of 81.2.  Estimated
planetary A indices were 11, 5, 5, 10, 4, 10, and 5, with a mean of
7.1.  Estimated mid-latitude A indices were 16, 7, 5, 6, 3, 10, and
5, with a mean of 7.4.