SB PROP @ ARL $ARLP030
ARLP030 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 30 ARLP030
From Tad Cook, K7RA
Seattle, WA July 24, 2020
To all radio amateurs
SB PROP ARL ARLP030
ARLP030 Propagation de K7RA
Another cycle 25 sunspot appeared this week (AR2767), with a minimum
non-zero sunspot number of 11 on July 21 to 23. Thus, the average
daily sunspot number for this reporting week (July 16 to 22) was
3.1, up from 1.7 over the previous seven days.
Geomagnetic indicators remain very quiet, with average daily
planetary A index declining from 5 to 3.9.
This sunspot cycle minimum remains surprisingly inactive. As time
goes on, I keep expecting it to perk up, but all indicators remain
One very hopeful outlook for cycle 25 comes from a group of
scientists who predict it possibly being one of the biggest cycles
of all time. Could we finally see a repeat of cycle 19? See their
Predicted solar flux, which roughly correlates to sunspot activity,
also looks quite dull. Until Thursday, the 45 day outlook had
predicted solar flux never at 70 or above.
Predicted flux values are 70 on July 24 to 31, 69 on August 1, 68 on
August 2 to 20, 69 again on August 21 to 28, and 68 on August 29
through September 6.
Predicted planetary A index is 8, 12, 8, and 5 on July 24 to 27, 5
on July 27, 8 on July 28 and 29, then 5, 8 and 10 on July 30 through
August 1, 5 on August 2 to 18, 8 on August 19 and 20, and 5 on
August 21 through September 5.
Spaceweather.com reports a possible coronal mass ejection impact
this week. The faint CME left the sun on July 19, and may cause a
minor disturbance on July 24 and 25. This is reflected in the
planetary A index forecast.
Geomagnetic activity forecast for the period July 24 to August 19,
2020 from OK1HH.
"Geomagnetic field will be
Quiet on: July 24 to 26, 28 and 29, August 4 to 7, 13 to 18
Quiet to unsettled on: July 27, 30, August 1 to 3, 10 to 12
Quiet to active on: (July 31, August 8 and 9, 19)
Unsettled to active: not expected
Active to disturbed: not expected
Solar wind will intensify on: July (23 to 27,) August 1 to 3 (- 4,
11 to 15)
- Parenthesis means lower probability of activity enhancement.
- The predictability of changes remains in the long run lower as
there are very few indications, as solar cycle minimum is here."
Wade Blake, N7LGK sent this link, showing current solar cycle
Last week exceptional HF conditions during the IARU HF World
Championship (July 11 and 12) were reported, and with no sunspots.
K7HV, K7SS and others reported conditions on Saturday night "like
the good old days" with worldwide propagation.
For more information concerning radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service 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 July 16 through 22, 2020 were 0, 0, 0, 0, 0, 11,
and 11, with a mean of 3.1. 10.7 cm flux was 68.7, 69, 67.8, 68.9,
69.3, 69.8, and 70, with a mean of 69.1. Estimated planetary A
indices were 4, 4, 4, 4, 4, 4, and 3, with a mean of 3.9. Middle
latitude A index was 4, 5, 4, 4, 3, 5, and 5, with a mean of 4.3.