QST de W1AW  
Propagation Forecast Bulletin 50  ARLP050
>From Tad Cook, K7RA
Seattle, WA  December 22, 2017
To all radio amateurs 

SB PROP ARL ARLP050
ARLP050 Propagation de K7RA

During the recent reporting week (December 14 to 20) the first six
days had zero sunspots. On December 20 one new sunspot group
appeared (2692) with a sunspot number of 16. The average daily
sunspot number decreased from 6.9 during the previous seven days to
2.3.
 
Average solar flux increased from 71 to 71.5, average planetary A
index went from 7.4 to 9.4, and mid-latitude A index increased from
5.5 to 6.1.
 
Predicted solar flux for the next 45 days is 75 on December 22 to
28, 74 on December 29 through January 1, 76 on January 2 to 5, 74 on
January 6 to 13, 72 on January 14 to 19, 74 on January 20 to 28, 76
on January 29 through February 1, and 74 on February 2 to 4.
 
Predicted planetary A index is 8 on December 22 and 23, 5 on
December 24 to 26, 10 and 8 on December 27 and 28, 5 on December 29
and 30, then 10, 25, 15 and 10 on December 31 through January 3, 5
on January 4 to 6, then 10, 12 and 8 on January 7 to 9, 5 on January
10 to 12, 22 on January 13 and 14, then 20, 16, 10 and 8 on January
15 to 18, 5 on January 19 to 22, 12 and 8 on January 23 and 24, 5 on
January 25 and 26, then 10, 25, 15 and 10 on January 27 to 30, 5 on
January 31 through February 2, 10 on February 3 and 12 on February
4.
 
F.K. Janda, OK1HH sent this:
 
'Geomagnetic activity forecast for the period December 22 to January
17, 2018
 
Geomagnetic field will be: 
Quiet on December 23, 26, January 5 and 6, 11 
Mostly quiet on December 22, 24, 30, January 4, 10, 15 
Quiet to unsettled on December 25, January 7, 17 
Quiet to active on December 27 to 29, 31, January 2 and 3, 8 and 9,
12, 14, 16 Active to disturbed on January 1, 13
 
Amplifications of the solar wind from coronal holes are expected on
December (24 to 28,) January 1 to 3, (6 to 8,) 10 to 13
 
Remark: 
- Parenthesis means lower probability of activity enhancement.' 
 
Kent Trimble, K9ZTV of Jefferson City, Missouri helpfully pointed
out that in last week's bulletin ARLP049 I wrote JT8 when I should
have written FT8. That line should read 'FT8 seems to have taken the
amateur radio service by storm in recent months, with an amazing
rate of acceptance due to its weak signal capabilities and easy
implementation.'
 
Not sure I trust the source, but this article has a number of
interesting references:
 
bit.ly/2kxhgxN 
 
The article mentions that in 2017 there have been 96 days (27
percent) with no sunspots, but as of this week that number is 101
days, or 28 percent, according to Spaceweather.com. The same list
shows that in 2009, 71 percent of the year had no sunspots.
 
Tamitha Skov posts great videos of her space weather predictions on
YouTube, but they are usually after my weekly bulletin is posted.
 
Check for her latest at:
 
https://www.youtube.com/user/SpWxfx 
 
I like the descriptions of space weather phenomena in this article: 
 
bit.ly/2BQsBAq 
 
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 December 14 to 20, 2017 were 0, 0, 0, 0, 0, 0,
and 16, with a mean of 2.3. 10.7 cm flux was 72.1, 71.7, 71.3, 71,
71.6, 68.8, and 74.2, with a mean of 71.5. Estimated planetary A
indices were 5, 5, 4, 24, 17, 6, and 5, with a mean of 9.4.
Estimated mid-latitude A indices were 2, 3, 3, 16, 12, 4, and 3,
with a mean of 6.1.