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ARRL Propagation Bulletin ARLP003 (2018)

SB PROP @ ARL $ARLP003
ARLP003 Propagation de K7RA

ZCZC AP03
QST de W1AW  
Propagation Forecast Bulletin 3  ARLP003
From Tad Cook, K7RA
Seattle, WA  January 19, 2018
To all radio amateurs 

SB PROP ARL ARLP003
ARLP003 Propagation de K7RA

It was a quiet week in space weather (January 11-17) with 0
sunspots over the weekend and geomagnetic indicators rising only
slightly.

Compared to last week, average daily sunspot numbers declined from
11.9 to 7, but average daily solar flux went from 69.9 to 70.7.
Seems counter-intuitive that sunspot and solar flux would move in
opposite directions, but these are all very low numbers anyway, and
any change is slight. Also, there are no sunspot numbers between
0 and 10 due to the arcane and somewhat confusing way they are
counted. The number gets 10 points for each sunspot group, and one
point for each sunspot in those groups. Therefore the minimum
possible sunspot number if there is any sunspot activity is 11.

Geomagnetic indicators were quiet, with average daily planetary A
index moving from 5.4 to 6.1, and mid-latitude A index from 4.6 to
4.9.

Predicted solar flux is 71 on January 19-25, 72 on January 26-27, 70
on January 28 to February 17, 72 on February 18-23, and 70 on
February 24 to March 4.

Predicted planetary A index is 8, 15, 12, 12, 10 and 8 on January
19-24,  5 on January 25-27, 10 on January 28, 5 on January 29 to
February 3, 8 on February 4-5, 5 on February 6-8, then 8, 12 and 10
on February 9-11, 5 on February 12-14, 20 on February 15-16, 18 and
12 on February 17-18, 5 on February 19-23, 10 on February 24, 5 on
February 25 to March 2, and 8 on March 3-4.

Geomagnetic activity forecast for the period January 19 to February
14, 2018 from F.K. Janda, OK1HH and the Czech Propagation Interest
Group.

"Geomagnetic field will be:
Quiet on January 19, 30-31, February 3, 6-8
Mostly quiet on February 2, 9
Quiet to unsettled on January 23-27, 29, February 1
Quiet to active on January 20-21, 28
Active to disturbed on January 22, February (4-5, 10)

"Amplifications of the solar wind from coronal holes are expected on
January 20-23, 28-31, February 5-6, (7, 9,) 10-12

"Remark:
- Parenthesis means lower probability of activity enhancement.
- Current forecasts are continuing to be less reliable."

Interesting article about preserving a long running hand-drawn
record of solar images:

http://bit.ly/2DmPnUF

For the latest from Dr. Tamitha Skov see:

https://www.youtube.com/channel/UCkXjdDQ-db0xz8f4PKgKsag

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 January 11-17, 2018 were 12, 0, 0, 0, 12, 13,
and 12, with a mean of 7. 10.7 cm flux was 70.8, 70.9, 70.8, 70.5,
70.2, 71.1, and 70.9, with a mean of 70.7. Estimated planetary A
indices were 2, 4, 7, 14, 9, 4, and 3, with a mean of 6.1. Estimated
mid-latitude A indices were 2, 3, 7, 11, 7, 3, and 1, with a mean of
4.9.
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/EX