SB PROP @ ARL $ARLP034
ARLP034 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 34 ARLP034
From Tad Cook, K7RA
Seattle, WA August 26, 2022
To all radio amateurs
SB PROP ARL ARLP034
ARLP034 Propagation de K7RA
On August 18 a new sunspot group emerged, another on August 21, then
two more on August 23, and three more on August 25, when the sunspot
number jumped to 94 from 46 the previous day. Total sunspot area
more than doubled from Wednesday to Thursday.
Solar activity overall was down slightly for the reporting week,
August 18-24, with average daily sunspot number declining from 60.8
during the previous seven days to 58.7, and average solar flux from
123.7 to 104.5.
Planetary A index changed from an average of 11.7 to 12.6, and
middle latitude A index measured at a single magnetometer in
Virginia was 11, after an average of 10 last week.
As an indicator of rising solar activity, a year ago this bulletin
reported average daily sunspot number at 17.7, 41 points below this
The Thursday night forecast from the 557th weather wing at Offut Air
Force Base shows a probable peak of solar flux for the near term at
130 on September 11 and again on October 8.
Predicted solar flux is 120 on August 26-27 (up from 105 in the
previous day's forecast), 115 on August 28, 110 on August 29-31, 115
on September 1-2, 116 on September 3-4, 112 on September 5, 108 on
September 6-7, then 115, 120, 124 and 130 on September 8-11, then
128, 120, 118, 105 and 102 on September 12-16, 98 on September
17-18, 96 on September 19-21, 94 on September 22-24, then 92, 98 and
100 on September 25-27, then 108, 114, 116 and 116 on September 28
through October 1.
Predicted planetary A index has some surprises in store, at 5 on
August 26, 8 on August 27-28, 10 on August 29, 5 on August 30-31, 8
September 1-2, then jumping way up to 30, 38 and 20 on September
3-5, then 15, 18, 10, 12 and 8 on September 6-10, 5 on September
11-12, then 12, 15 and 10 on September 13-15, 8 on September 16-17,
then 25, 15 and 8 on September 18-20, 5 on September 21-22, 12 on
September 23, then 8 on September 24-26, 5 on September 27-29, then
back up to 30, 38, 20, 15 and 18 on September 30 through October 4,
an apparent echo of the prediction for September 3-7.
The above predictions were from USAF forecasters Easterlin and
F.K. Janda, OK1HH wrote:
"As in the previous solar rotation, the Sun's activity continued to
decline. Geomagnetic activity, however, has increased. More
pronounced eruptive activity was mainly in the southwest quadrant of
the solar disk.
"The active sunspot, AR3078, produced several M-class solar flares
and more than a dozen C-class flares. Most of the eruptions hurled
particles into space. The first CME hit Earth's magnetic field on
August 20. The next active sunspot group, AR3085, behaved similarly
after reaching the same active heliographic longitude as the
previous sunspot, AR3078.
"Sunspot AR3085 grew more than ten times larger and turned into a
double sunspot group with cores almost as wide as the Earth.
Finally, a new sunspot, AR3088, appeared, again in the southern
hemisphere of the Sun.
"Attention is now drawn to a large coronal hole in the southeastern
solar disk that could affect the solar wind after it appears near
the central meridian.
"With the current type of development, predictions of further events
are more difficult than usual. Either way, we now expect a
quasi-periodic increase in solar activity."
Here is a news article about a large sunspot:
British tabloid sunspot news:
Here is an article about a planet-sized sunspot:
A Nature World News story about a big sunspot:
A report about eleven discoveries and the coming solar max, from
American Geophysical Union:
From Space.com, the threat of unexpected flares:
Here is a paper on solar rotations:
I did not include an article titled "Destructive solar storms are
possible as Sun approaches height of its terrifying solar cycle."
The article claimed that Solar Cycle 25 peak will be a year from
now, rather than the consensus prediction of 2025.
Send your tips, reports, observations, questions, and comments to
For more information concerning shortwave 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/ .
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for August 18 through 24, 2022 were 83, 74, 56, 56,
44, 52, and 46, with a mean of 58.7. 10.7 cm flux was 116.5, 105.4,
101.5, 97, 102.6, 100.9, and 107.8, with a mean of 104.5. Estimated
planetary A indices were 26, 20, 14, 14, 7, 4, and 3, with a mean of
12.6. Middle latitude A index was 19, 15, 16, 13, 7, 3, and 4, with
a mean of 11.