SB PROP @ ARL $ARLP026
ARLP026 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 26 ARLP026
From Tad Cook, K7RA
Seattle, WA June 26, 2020
To all radio amateurs
SB PROP ARL ARLP026
ARLP026 Propagation de K7RA
No sunspots were observed since June 15, when the daily sunspot
number was 11. This does not mean there were 11 sunspots seen, but
instead it means that one sunspot group was observed containing one
sunspot. The sunspot number is derived by assigning 10 points for
each sunspot group, and one point for each sunspot. So 11 is the
minimum non-zero sunspot number.
On June 8 the daily sunspot number was 17, indicating 7 sunspots in
If those seven sunspots had been in two groups, the sunspot number
would be reported as 27.
Last week's bulletin Propagation Forecast Bulletin ARLP025 reported
an average daily sunspot number of 7.9, and of course with no
sunspots, this week that number dropped to 0.
Average daily solar flux declined from 70 to 67.7.
The Sun has gone quiet again, as http://www.spaceweather.com
reported this week.
Geomagnetic indicators are still very quiet, but the average
planetary A index rose from 3.9 to 4.6 and the average middle
latitude A index rose from 4.9 to 5.6. These values are
Predicted solar flux for the next 45 days is 69 on June 26 through
July 3, 70 on July 4-12, 68 on July 13-25, 70 on July 26 through
August 8 and 68 on August 9.
Predicted planetary A index is 5 on June 26, 8 on June 27, 5 on June
28 through July 3, then 8, 5, 8 and 8 on July 4-7, 5 on July 8-30,
then 8, 5, 8 and 8 again on July 31 through August 3, and 5 on
Geomagnetic activity forecast for the period June 26 until July 22,
2020 from F.K. Janda, OK1HH.
"Geomagnetic field will be
quiet on: June 28, 30, July 1, (2,) 3, (6,) 9-11, 14-15, 18-20, 22
quiet to unsettled on: June 27, 29, July 4, 8, 12-13, 17, 21
quiet to active on: (June 26, July 5, 7, 16)
unsettled to active: nothing predicted
active to disturbed: nothing predicted
"Solar wind will intensify on: June 26-27, (28-30,) July (4,) 5-8,
(9-10, 16-18, 22).
"Parenthesis means lower probability of activity enhancement. The
predictability of changes remains lower as there are very few
A new video from Dr, Tamitha Skov, WX6SWW:
A Phys.org article on the inner workings of our Sun:
Highly technical article on sunspots from Astronomy and
This weekend is ARRL Field Day, the most popular annual operating
The 2020 Field Day has a rule waiver for this year allowing Class D
stations operating from home and on commercial power to work each
other. In the past they could only work all the other classes of
Some operators don't realize that Field Day has only minimal logging
requirements, just submit a list or dupe sheet for each band/mode
showing the calls of the stations worked, and a summary sheet. There
is no requirement to log the time of each contact, or even record
the section or any report from stations you work. See the rules at:
If you would like to make a comment or have a tip for our readers,
email the author at, firstname.lastname@example.org.
For more information concerning radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, at http://arrl.org/propagation-of-rf-signals.
For an explanation of numbers used in this bulletin, see
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 June 18 through 24, 2020 were 0, 0, 0, 0, 0, 0,
and 0, with a mean of 0. 10.7 cm flux was 67.9, 68.8, 67.8, 67.6,
67.6, 67.1, and 66.9, with a mean of 67.7. Estimated planetary A
indices were 4, 5, 6, 4, 4, 4, and 5, with a mean of 4.6. Middle
latitude A index was 5, 7, 7, 4, 3, 6, and 7, with a mean of 5.6.