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ARRL Propagation Bulletin ARLP025 (2022)

ARLP025 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7RA
Seattle, WA  June 24, 2022
To all radio amateurs 

ARLP025 Propagation de K7RA

This past reporting week (June 16-22) began with a bang, when the
daily sunspot number was 159. But sunspot numbers declined every day
to finally reach 80 on June 22.

One new sunspot group emerged on June 15, another on June 16, one
more on June 18, and another on June 21.

Average daily sunspot number over the week was 124.6, up
substantially from 74.3 the previous seven days.

Average daily solar flux rose from 123.9 to 140.5.

Average daily planetary A index rose from 9.7 to 11.4, and the
middle latitude numbers increased one point to 11.9

It was great to see the Sun covered with spots on
Use the Archives feature toward the upper right, and you can see the
daily solar images on the left side of the page for any date in the
past. I particularly appreciated the image of June 17, our Sun
blanketed with sunspots!

Unfortunately, a California wildfire cut off power to the Solar
Dynamics Observatory Data Center at Stanford University, so solar
images are not being provided, according to

ARRL Field Day is this weekend. What is the outlook?

The latest from US Air Force forecasters Housseal and King at the
USAF 557th Weather Wing shows predicted solar flux at 120, 115 and
110 on June 24-26, and Planetary A index of 8, 12 and 15. Field Day
is actually on June 25-26, but it is useful to see the prediction
for Friday. The planetary A index shoes a moderate but increasing
geomagnetic instability.

Newsweek reported a recent sunspot:

The latest (Thursday night) forecast from USAF shows solar flux at
120 and 115 on June 24-25, 110 on June 26-27, 100 on June 28-29, 105
on June 30, 100 on July 1-2, then 105, 110, 115, 120 and 125 on July
3-7, 130 on July 8-9, 135 on July 10, 140 on July 11-16, then 138,
134, 125 and 121 on July 17-20, then 114, 118 and 105 on July 21-23,
100 on July 24-29, then 105, 110, 115 and 120 on July 30 through
August 2.

The planetary A index prediction is 8, 12, and 15 on June 24-26, 5
on June 27 to July 7, then 8, 8, 12 and 8 on July 8-11, 5 on July 12-13,
12 on July 14-16, 10 on July 17, 5 on July 18-19, then 12, 18, 12 and 10
on July 20-23, then 5 on July 24 through August 3, and 8 on August 4-5.

F.K. Janda, OK1HH wrote:

"The distribution of active areas on the Sun according to
heliographic latitudes has changed relatively little during the last
three solar rotations, therefore the predictions of the overall
solar activity level were quite reliable.

"The parameters of the solar wind, measured around the Earth, and
the activity of the geomagnetic field had a similar course.

"The highest usable frequencies of the ionospheric layer F2 (MUF)
were increased on June 19-20. The sporadic E layer played the most
important role in the shortwave propagation on June 16-19."

The latest space weather video from Dr. Tamitha Skov, WX6SWW:

A story about how "We can't reliably predict solar cycles" can be
found at:

I have no idea what prompted an incredible series of news stories
late Thursday. Was it a slow news day? Perhaps an indication of a
respite from national tragedies?

The following websites contain stories about our Sun, and the
emergence of a big spot. Interesting because on Thursday the sunspot
number declined to 69 from 80 the day before, and much lower
compared to the 124.6 average for the previous seven days:

If you would like to make a comment or have a tip for our readers,
please email the author at, k7ra (at) .

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service web page at, . For
an explanation of numbers used in this bulletin, see .

An archive of past propagation bulletins is at . More good
information and tutorials on propagation are at .

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for June 16 through 22, 2022 were 159, 152, 145,
120, 112, 104, and 80, with a mean of 124.6. 10.7 cm flux was 146.7,
148.9, 140.2, 143.6, 136.5, 138.8, and 128.7, with a mean of 140.5.
Estimated planetary A indices were 12, 13, 14, 12, 10, 8, and 11,
with a mean of 11.4. Middle latitude A index was 14, 14, 15, 10, 10,
10, and 10, with a mean of 11.9.


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